redis详细配置

   1 ##redis配置详解
   2 
   3 # Redis configuration file example.
   4 #
   5 # Note that in order to read the configuration file, Redis must be
   6 # started with the file path as first argument:
   7 #
   8 # ./redis-server /path/to/redis.conf
   9 
  10 # Note on units: when memory size is needed, it is possible to specify
  11 # it in the usual form of 1k 5GB 4M and so forth:
  12 #
  13 # 1k => 1000 bytes
  14 # 1kb => 1024 bytes
  15 # 1m => 1000000 bytes
  16 # 1mb => 1024*1024 bytes
  17 # 1g => 1000000000 bytes
  18 # 1gb => 1024*1024*1024 bytes
  19 #
  20 # units are case insensitive so 1GB 1Gb 1gB are all the same.
  21 
  22 ################################## INCLUDES ###################################
  23 ################################## 包含     ###################################
  24 
  25 # Include one or more other config files here.  This is useful if you
  26 # have a standard template that goes to all Redis servers but also need
  27 # to customize a few per-server settings.  Include files can include
  28 # other files, so use this wisely.
  29 #
  30 # Notice option "include" won't be rewritten by command "CONFIG REWRITE"
  31 # from admin or Redis Sentinel. Since Redis always uses the last processed
  32 # line as value of a configuration directive, you'd better put includes
  33 # at the beginning of this file to avoid overwriting config change at runtime.
  34 #
  35 # If instead you are interested in using includes to override configuration
  36 # options, it is better to use include as the last line.
  37 #
  38 # 假如说你有一个可用于所有的 redis server 的标准配置模板,
  39 # 但针对某些 server 又需要一些个性化的设置,
  40 # 你可以使用 include 来包含一些其他的配置文件,这对你来说是非常有用的。
  41 #
  42 # 但是要注意哦,include 是不能被 config rewrite 命令改写的
  43 # 由于 redis 总是以最后的加工线作为一个配置指令值,所以你最好是把 include 放在这个文件的最前面,
  44 # 以避免在运行时覆盖配置的改变,相反,你就把它放在后面
  45 # include /path/to/local.conf
  46 # include /path/to/other.conf
  47 
  48 ################################ GENERAL  #####################################
  49 ################################ 常用     #####################################
  50 
  51 # By default Redis does not run as a daemon. Use 'yes' if you need it.
  52 # Note that Redis will write a pid file in /var/run/redis.pid when daemonized.
  53 # 默认情况下 redis 不是作为守护进程运行的,如果你想让它在后台运行,你就把它改成 yes。
  54 # 当redis作为守护进程运行的时候,它会写一个 pid 到 /var/run/redis.pid 文件里面。
  55 daemonize yes
  56 
  57 # When running daemonized, Redis writes a pid file in /var/run/redis.pid by
  58 # default. You can specify a custom pid file location here.
  59 # 当 Redis 以守护进程的方式运行的时候,Redis 默认会把 pid 文件放在/var/run/redis.pid
  60 # 可配置到其他地址,当运行多个 redis 服务时,需要指定不同的 pid 文件和端口
  61 # 指定存储Redis进程号的文件路径
  62 pidfile /var/run/redis.pid
  63 
  64 # Accept connections on the specified port, default is 6379.
  65 # If port 0 is specified Redis will not listen on a TCP socket.
  66 # 端口,默认端口是6379,生产环境中建议更改端口号,安全性更高
  67 # 如果你设为 0 ,redis 将不在 socket 上监听任何客户端连接。
  68 port 9966
  69 
  70 # TCP listen() backlog.
  71 #
  72 # In high requests-per-second environments you need an high backlog in order
  73 # to avoid slow clients connections issues. Note that the Linux kernel
  74 # will silently truncate it to the value of /proc/sys/net/core/somaxconn so
  75 # make sure to raise both the value of somaxconn and tcp_max_syn_backlog
  76 # in order to get the desired effect.
  77 # TCP 监听的最大容纳数量
  78 # 此参数确定了TCP连接中已完成队列(完成三次握手之后)的长度,
  79 # 当系统并发量大并且客户端速度缓慢的时候,你需要把这个值调高以避免客户端连接缓慢的问题。
  80 # Linux 内核会一声不响的把这个值缩小成 /proc/sys/net/core/somaxconn 对应的值,默认是511,而Linux的默认参数值是128。
  81 # 所以可以将这二个参数一起参考设定,你以便达到你的预期。
  82 #  
  83 tcp-backlog 511
  84 
  85 # By default Redis listens for connections from all the network interfaces
  86 # available on the server. It is possible to listen to just one or multiple
  87 # interfaces using the "bind" configuration directive, followed by one or
  88 # more IP addresses.
  89 #
  90 # Examples:
  91 #
  92 # bind 192.168.1.100 10.0.0.1
  93 # 有时候为了安全起见,redis一般都是监听127.0.0.1 但是有时候又有同网段能连接的需求,当然可以绑定0.0.0.0 用iptables来控制访问权限,或者设置redis访问密码来保证数据安全
  94 
  95 # 不设置将处理所有请求,建议生产环境中设置,有个误区:bind是用来限制外网IP访问的,其实不是,限制外网ip访问可以通过iptables;如:-A INPUT -s 10.10.1.0/24 -p tcp -m state --state NEW -m tcp --dport 9966 -j ACCEPT ;
  96 # 实际上,bind ip 绑定的是redis所在服务器网卡的ip,当然127.0.0.1也是可以的
  97 #如果绑定一个外网ip,就会报错:Creating Server TCP listening socket xxx.xxx.xxx.xxx:9966: bind: Cannot assign requested address
  98 
  99 # bind 127.0.0.1
 100 bind 127.0.0.1 10.10.1.3
 101 
 102 # 假设绑定是以上ip,使用 netstat -anp|grep 9966 会发现,这两个ip被bind,其中10.10.1.3是服务器网卡的ip
 103 # tcp        0      0 10.10.1.3:9966         0.0.0.0:*                   LISTEN      11188/redis-server  
 104 # tcp        0      0 127.0.0.1:9966         0.0.0.0:*                   LISTEN      11188/redis-server 
 105 
 106 
 107 # Specify the path for the Unix socket that will be used to listen for
 108 # incoming connections. There is no default, so Redis will not listen
 109 # on a unix socket when not specified.
 110 #
 111 # unixsocket /tmp/redis.sock
 112 # unixsocketperm 700
 113 
 114 # Close the connection after a client is idle for N seconds (0 to disable)
 115 # 客户端和Redis服务端的连接超时时间,默认是0,表示永不超时。
 116 timeout 0
 117 
 118 # TCP keepalive.
 119 #
 120 # If non-zero, use SO_KEEPALIVE to send TCP ACKs to clients in absence
 121 # of communication. This is useful for two reasons:
 122 #
 123 # 1) Detect dead peers.
 124 # 2) Take the connection alive from the point of view of network
 125 #    equipment in the middle.
 126 #
 127 # On Linux, the specified value (in seconds) is the period used to send ACKs.
 128 # Note that to close the connection the double of the time is needed.
 129 # On other kernels the period depends on the kernel configuration.
 130 #
 131 # A reasonable value for this option is 60 seconds.
 132 
 133 # tcp 心跳包。
 134 #
 135 # 如果设置为非零,则在与客户端缺乏通讯的时候使用 SO_KEEPALIVE 发送 tcp acks 给客户端。
 136 # 这个之所有有用,主要由两个原因:
 137 #
 138 # 1) 防止死的 peers
 139 # 2) Take the connection alive from the point of view of network
 140 #    equipment in the middle.
 141 #
 142 # 推荐一个合理的值就是60秒
 143 tcp-keepalive 0
 144 
 145 # Specify the server verbosity level.
 146 # This can be one of:
 147 # debug (a lot of information, useful for development/testing)
 148 # verbose (many rarely useful info, but not a mess like the debug level)
 149 # notice (moderately verbose, what you want in production probably)
 150 # warning (only very important / critical messages are logged)
 151 # 日志记录等级,4个可选值debug,verbose,notice,warning
 152 # 可以是下面的这些值:
 153 # debug (适用于开发或测试阶段)
 154 # verbose (many rarely useful info, but not a mess like the debug level)
 155 # notice (适用于生产环境)
 156 # warning (仅仅一些重要的消息被记录)
 157 loglevel notice
 158 
 159 # Specify the log file name. Also the empty string can be used to force
 160 # Redis to log on the standard output. Note that if you use standard
 161 # output for logging but daemonize, logs will be sent to /dev/null
 162 #配置 log 文件地址,默认打印在命令行终端的窗口上,也可设为/dev/null屏蔽日志、
 163 logfile "/data/logs/redis/redis.log"
 164 
 165 # To enable logging to the system logger, just set 'syslog-enabled' to yes,
 166 # and optionally update the other syslog parameters to suit your needs.
 167 # 要想把日志记录到系统日志,就把它改成 yes,
 168 # 也可以可选择性的更新其他的syslog 参数以达到你的要求
 169 # syslog-enabled no
 170 
 171 # Specify the syslog identity.
 172 # 设置 syslog 的 identity。
 173 # syslog-ident redis
 174 
 175 # Specify the syslog facility. Must be USER or between LOCAL0-LOCAL7.
 176 # syslog-facility local0
 177 
 178 # Set the number of databases. The default database is DB 0, you can select
 179 # a different one on a per-connection basis using SELECT <dbid> where
 180 # dbid is a number between 0 and 'databases'-1
 181 # 可用的数据库数,默认值为16,默认数据库为0,数据库范围在0-(database-1)之间
 182 databases 16
 183 
 184 ################################ SNAPSHOTTING  ################################
 185 ################################ 快照          ################################
 186 #
 187 # Save the DB on disk:
 188 #
 189 #   save <seconds> <changes>
 190 #
 191 #   Will save the DB if both the given number of seconds and the given
 192 #   number of write operations against the DB occurred.
 193 #
 194 #   In the example below the behaviour will be to save:
 195 #   after 900 sec (15 min) if at least 1 key changed
 196 #   after 300 sec (5 min) if at least 10 keys changed
 197 #   after 60 sec if at least 10000 keys changed
 198 #
 199 #   Note: you can disable saving completely by commenting out all "save" lines.
 200 #
 201 #   It is also possible to remove all the previously configured save
 202 #   points by adding a save directive with a single empty string argument
 203 #   like in the following example:
 204 #
 205 #   save ""
 206 # 在 900 秒内最少有 1 个 key 被改动,或者 300 秒内最少有 10 个 key 被改动,又或者 60 秒内最少有 1000 个 key 被改动,以上三个条件随便满足一个,就触发一次保存操作。
 207 
 208 #    if(在60秒之内有10000个keys发生变化时){
 209 #      进行镜像备份
 210 #    }else if(在300秒之内有10个keys发生了变化){
 211 #      进行镜像备份
 212 #    }else if(在900秒之内有1个keys发生了变化){
 213 #      进行镜像备份
 214 #    }
 215 
 216 save 900 1
 217 save 300 10
 218 save 60 10000
 219 
 220 # By default Redis will stop accepting writes if RDB snapshots are enabled
 221 # (at least one save point) and the latest background save failed.
 222 # This will make the user aware (in a hard way) that data is not persisting
 223 # on disk properly, otherwise chances are that no one will notice and some
 224 #:/ disaster will happen.
 225 #
 226 # If the background saving process will start working again Redis will
 227 # automatically allow writes again.
 228 #
 229 # However if you have setup your proper monitoring of the Redis server
 230 # and persistence, you may want to disable this feature so that Redis will
 231 # continue to work as usual even if there are problems with disk,
 232 # permissions, and so forth.
 233 # 默认情况下,如果 redis 最后一次的后台保存失败,redis 将停止接受写操作,
 234 # 这样以一种强硬的方式让用户知道数据不能正确的持久化到磁盘,
 235 # 否则就会没人注意到灾难的发生。
 236 #
 237 # 如果后台保存进程重新启动工作了,redis 也将自动的允许写操作。
 238 #
 239 # 然而你要是安装了靠谱的监控,你可能不希望 redis 这样做,那你就改成 no 好
 240 stop-writes-on-bgsave-error yes
 241 
 242 # Compress string objects using LZF when dump .rdb databases?
 243 # For default that's set to 'yes' as it's almost always a win.
 244 # If you want to save some CPU in the saving child set it to 'no' but
 245 # the dataset will likely be bigger if you have compressible values or keys.
 246 # 在进行备份时,是否进行压缩
 247 # 是否在 dump .rdb 数据库的时候使用 LZF 压缩字符串
 248 # 默认都设为 yes
 249 # 如果你希望保存子进程节省点 cpu ,你就设置它为 no ,
 250 # 不过这个数据集可能就会比较大
 251 rdbcompression yes
 252 
 253 # Since version 5 of RDB a CRC64 checksum is placed at the end of the file.
 254 # This makes the format more resistant to corruption but there is a performance
 255 # hit to pay (around 10%) when saving and loading RDB files, so you can disable it
 256 # for maximum performances.
 257 #
 258 # RDB files created with checksum disabled have a checksum of zero that will
 259 # tell the loading code to skip the check.    
 260 # 读取和写入的时候是否支持CRC64校验,默认是开启的
 261 rdbchecksum yes
 262 
 263 # The filename where to dump the DB
 264 # 备份文件的文件名
 265 dbfilename dump.rdb
 266 
 267 # The working directory.
 268 #
 269 # The DB will be written inside this directory, with the filename specified
 270 # above using the 'dbfilename' configuration directive.
 271 #
 272 # The Append Only File will also be created inside this directory.
 273 #
 274 # Note that you must specify a directory here, not a file name.
 275 # 数据库备份的文件放置的路径
 276 # 路径跟文件名分开配置是因为 Redis 备份时,先会将当前数据库的状态写入到一个临时文件
 277 # 等备份完成时,再把该临时文件替换为上面所指定的文件
 278 # 而临时文件和上面所配置的备份文件都会放在这个指定的路径当中
 279 # 默认值为 ./
 280 dir /data/data/redis/
 281 
 282 ################################# REPLICATION #################################
 283 ################################# 主从复制    #################################
 284 # Master-Slave replication. Use slaveof to make a Redis instance a copy of
 285 # another Redis server. A few things to understand ASAP about Redis replication.
 286 #
 287 # 1) Redis replication is asynchronous, but you can configure a master to
 288 #    stop accepting writes if it appears to be not connected with at least
 289 #    a given number of slaves.
 290 # 2) Redis slaves are able to perform a partial resynchronization with the
 291 #    master if the replication link is lost for a relatively small amount of
 292 #    time. You may want to configure the replication backlog size (see the next
 293 #    sections of this file) with a sensible value depending on your needs.
 294 # 3) Replication is automatic and does not need user intervention. After a
 295 #    network partition slaves automatically try to reconnect to masters
 296 #    and resynchronize with them.
 297 #
 298 # 设置该数据库为其他数据库的从数据库
 299 # slaveof <masterip> <masterport> 当本机为从服务时,设置主服务的IP及端口
 300 # slaveof <masterip> <masterport>
 301 
 302 # If the master is password protected (using the "requirepass" configuration
 303 # directive below) it is possible to tell the slave to authenticate before
 304 # starting the replication synchronization process, otherwise the master will
 305 # refuse the slave request.
 306 #
 307 # 指定与主数据库连接时需要的密码验证
 308 # masterauth <master-password> 当本机为从服务时,设置访问master服务器的密码
 309 # masterauth <master-password>
 310 
 311 # When a slave loses its connection with the master, or when the replication
 312 # is still in progress, the slave can act in two different ways:
 313 #
 314 # 1) if slave-serve-stale-data is set to 'yes' (the default) the slave will
 315 #    still reply to client requests, possibly with out of date data, or the
 316 #    data set may just be empty if this is the first synchronization.
 317 #
 318 # 2) if slave-serve-stale-data is set to 'no' the slave will reply with
 319 #    an error "SYNC with master in progress" to all the kind of commands
 320 #    but to INFO and SLAVEOF.
 321 #
 322 # 当slave服务器和master服务器失去连接后,或者当数据正在复制传输的时候,如果此参数值设置“yes”,slave服务器可以继续接受客户端的请求,否则,会返回给请求的客户端如下信息“SYNC with master in progress”,除了INFO,SLAVEOF这两个命令
 323 slave-serve-stale-data yes
 324 
 325 # You can configure a slave instance to accept writes or not. Writing against
 326 # a slave instance may be useful to store some ephemeral data (because data
 327 # written on a slave will be easily deleted after resync with the master) but
 328 # may also cause problems if clients are writing to it because of a
 329 # misconfiguration.
 330 #
 331 # Since Redis 2.6 by default slaves are read-only.
 332 #
 333 # Note: read only slaves are not designed to be exposed to untrusted clients
 334 # on the internet. It's just a protection layer against misuse of the instance.
 335 # Still a read only slave exports by default all the administrative commands
 336 # such as CONFIG, DEBUG, and so forth. To a limited extent you can improve
 337 # security of read only slaves using 'rename-command' to shadow all the
 338 # administrative / dangerous commands.
 339 # 是否允许slave服务器节点只提供读服务
 340 slave-read-only yes
 341 
 342 # Replication SYNC strategy: disk or socket.
 343 #
 344 # -------------------------------------------------------
 345 # WARNING: DISKLESS REPLICATION IS EXPERIMENTAL CURRENTLY
 346 # -------------------------------------------------------
 347 #
 348 # New slaves and reconnecting slaves that are not able to continue the replication
 349 # process just receiving differences, need to do what is called a "full
 350 # synchronization". An RDB file is transmitted from the master to the slaves.
 351 # The transmission can happen in two different ways:
 352 #
 353 # 1) Disk-backed: The Redis master creates a new process that writes the RDB
 354 #                 file on disk. Later the file is transferred by the parent
 355 #                 process to the slaves incrementally.
 356 # 2) Diskless: The Redis master creates a new process that directly writes the
 357 #              RDB file to slave sockets, without touching the disk at all.
 358 #
 359 # With disk-backed replication, while the RDB file is generated, more slaves
 360 # can be queued and served with the RDB file as soon as the current child producing
 361 # the RDB file finishes its work. With diskless replication instead once
 362 # the transfer starts, new slaves arriving will be queued and a new transfer
 363 # will start when the current one terminates.
 364 #
 365 # When diskless replication is used, the master waits a configurable amount of
 366 # time (in seconds) before starting the transfer in the hope that multiple slaves
 367 # will arrive and the transfer can be parallelized.
 368 #
 369 # With slow disks and fast (large bandwidth) networks, diskless replication
 370 # works better.
 371 repl-diskless-sync no
 372 
 373 # When diskless replication is enabled, it is possible to configure the delay
 374 # the server waits in order to spawn the child that transfers the RDB via socket
 375 # to the slaves.
 376 #
 377 # This is important since once the transfer starts, it is not possible to serve
 378 # new slaves arriving, that will be queued for the next RDB transfer, so the server
 379 # waits a delay in order to let more slaves arrive.
 380 #
 381 # The delay is specified in seconds, and by default is 5 seconds. To disable
 382 # it entirely just set it to 0 seconds and the transfer will start ASAP.
 383 repl-diskless-sync-delay 5
 384 
 385 # Slaves send PINGs to server in a predefined interval. It's possible to change
 386 # this interval with the repl_ping_slave_period option. The default value is 10
 387 # seconds.
 388 #
 389 # Slaves 在一个预定义的时间间隔内发送 ping 命令到 server 。
 390 # 你可以改变这个时间间隔。默认为 10 秒。
 391 # repl-ping-slave-period 10
 392 
 393 # The following option sets the replication timeout for:
 394 #
 395 # 1) Bulk transfer I/O during SYNC, from the point of view of slave.
 396 # 2) Master timeout from the point of view of slaves (data, pings).
 397 # 3) Slave timeout from the point of view of masters (REPLCONF ACK pings).
 398 #
 399 # It is important to make sure that this value is greater than the value
 400 # specified for repl-ping-slave-period otherwise a timeout will be detected
 401 # every time there is low traffic between the master and the slave.
 402 #
 403 # 设置主从复制过期时间
 404 # 这个值一定要比 repl-ping-slave-period 大
 405 # repl-timeout 60
 406 
 407 # Disable TCP_NODELAY on the slave socket after SYNC?
 408 #
 409 # If you select "yes" Redis will use a smaller number of TCP packets and
 410 # less bandwidth to send data to slaves. But this can add a delay for
 411 # the data to appear on the slave side, up to 40 milliseconds with
 412 # Linux kernels using a default configuration.
 413 #
 414 # If you select "no" the delay for data to appear on the slave side will
 415 # be reduced but more bandwidth will be used for replication.
 416 #
 417 # By default we optimize for low latency, but in very high traffic conditions
 418 # or when the master and slaves are many hops away, turning this to "yes" may
 419 # be a good idea.
 420 # 指定向slave同步数据时,是否禁用socket的NO_DELAY选 项。若配置为“yes”,则禁用NO_DELAY,则TCP协议栈会合并小包统一发送,这样可以减少主从节点间的包数量并节省带宽,但会增加数据同步到 slave的时间。若配置为“no”,表明启用NO_DELAY,则TCP协议栈不会延迟小包的发送时机,这样数据同步的延时会减少,但需要更大的带宽。 通常情况下,应该配置为no以降低同步延时,但在主从节点间网络负载已经很高的情况下,可以配置为yes。
 421 repl-disable-tcp-nodelay no
 422 
 423 # Set the replication backlog size. The backlog is a buffer that accumulates
 424 # slave data when slaves are disconnected for some time, so that when a slave
 425 # wants to reconnect again, often a full resync is not needed, but a partial
 426 # resync is enough, just passing the portion of data the slave missed while
 427 # disconnected.
 428 #
 429 # The bigger the replication backlog, the longer the time the slave can be
 430 # disconnected and later be able to perform a partial resynchronization.
 431 #
 432 # The backlog is only allocated once there is at least a slave connected.
 433 #
 434 # 设置主从复制容量大小。这个 backlog 是一个用来在 slaves 被断开连接时
 435 # 存放 slave 数据的 buffer,所以当一个 slave 想要重新连接,通常不希望全部重新同步,
 436 # 只是部分同步就够了,仅仅传递 slave 在断开连接时丢失的这部分数据。
 437 #
 438 # The biggest the replication backlog, the longer the time the slave can be
 439 # disconnected and later be able to perform a partial resynchronization.
 440 # 这个值越大,salve 可以断开连接的时间就越长。
 441 
 442 # repl-backlog-size 1mb
 443 
 444 # After a master has no longer connected slaves for some time, the backlog
 445 # will be freed. The following option configures the amount of seconds that
 446 # need to elapse, starting from the time the last slave disconnected, for
 447 # the backlog buffer to be freed.
 448 #
 449 # A value of 0 means to never release the backlog.
 450 #
 451 # 在某些时候,master 不再连接 slaves,backlog 将被释放。
 452 # 如果设置为 0 ,意味着绝不释放 backlog 。
 453 # repl-backlog-ttl 3600
 454 
 455 # The slave priority is an integer number published by Redis in the INFO output.
 456 # It is used by Redis Sentinel in order to select a slave to promote into a
 457 # master if the master is no longer working correctly.
 458 #
 459 # A slave with a low priority number is considered better for promotion, so
 460 # for instance if there are three slaves with priority 10, 100, 25 Sentinel will
 461 # pick the one with priority 10, that is the lowest.
 462 #
 463 # However a special priority of 0 marks the slave as not able to perform the
 464 # role of master, so a slave with priority of 0 will never be selected by
 465 # Redis Sentinel for promotion.
 466 #
 467 # By default the priority is 100.
 468 # 指定slave的优先级。在不只1个slave存在的部署环境下,当master宕机时,Redis
 469 # Sentinel会将priority值最小的slave提升为master。
 470 # 这个值越小,就越会被优先选中,需要注意的是,
 471 # 若该配置项为0,则对应的slave永远不会自动提升为master。
 472 slave-priority 100
 473 
 474 # It is possible for a master to stop accepting writes if there are less than
 475 # N slaves connected, having a lag less or equal than M seconds.
 476 #
 477 # The N slaves need to be in "online" state.
 478 #
 479 # The lag in seconds, that must be <= the specified value, is calculated from
 480 # the last ping received from the slave, that is usually sent every second.
 481 #
 482 # This option does not GUARANTEE that N replicas will accept the write, but
 483 # will limit the window of exposure for lost writes in case not enough slaves
 484 # are available, to the specified number of seconds
 485 #
 486 # For example to require at least 3 slaves with a lag <= 10 seconds use:
 487 #
 488 # min-slaves-to-write 3
 489 # min-slaves-max-lag 10
 490 #
 491 # Setting one or the other to 0 disables the feature.
 492 #
 493 # By default min-slaves-to-write is set to 0 (feature disabled) and
 494 # min-slaves-max-lag is set to 10.
 495 
 496 ################################## SECURITY ###################################
 497 ################################## 安全     ###################################
 498 
 499 # Require clients to issue AUTH <PASSWORD> before processing any other
 500 # commands.  This might be useful in environments in which you do not trust
 501 # others with access to the host running redis-server.
 502 #
 503 # This should stay commented out for backward compatibility and because most
 504 # people do not need auth (e.g. they run their own servers).
 505 #
 506 # Warning: since Redis is pretty fast an outside user can try up to
 507 # 150k passwords per second against a good box. This means that you should
 508 # use a very strong password otherwise it will be very easy to break.
 509 #
 510 # 设置连接redis的密码
 511 # redis速度相当快,一个外部用户在一秒钟进行150K次密码尝试,需指定强大的密码来防止暴力破解
 512 requirepass set_enough_strong_passwd
 513 
 514 # Command renaming.
 515 #
 516 # It is possible to change the name of dangerous commands in a shared
 517 # environment. For instance the CONFIG command may be renamed into something
 518 # hard to guess so that it will still be available for internal-use tools
 519 # but not available for general clients.
 520 #
 521 # Example:
 522 #
 523 # rename-command CONFIG b840fc02d524045429941cc15f59e41cb7be6c52
 524 #
 525 # It is also possible to completely kill a command by renaming it into
 526 # an empty string:
 527 #
 528 # rename-command CONFIG ""
 529 #
 530 # Please note that changing the name of commands that are logged into the
 531 # AOF file or transmitted to slaves may cause problems.
 532 # 重命名一些高危命令,用来禁止高危命令
 533 rename-command FLUSHALL ZYzv6FOBdwflW2nX
 534 rename-command CONFIG aI7zwm1GDzMMrEi
 535 rename-command EVAL S9UHPKEpSvUJMM
 536 rename-command FLUSHDB D60FPVDJuip7gy6l
 537 
 538 ################################### LIMITS ####################################
 539 ################################### 限制   ####################################
 540 
 541 # Set the max number of connected clients at the same time. By default
 542 # this limit is set to 10000 clients, however if the Redis server is not
 543 # able to configure the process file limit to allow for the specified limit
 544 # the max number of allowed clients is set to the current file limit
 545 # minus 32 (as Redis reserves a few file descriptors for internal uses).
 546 #
 547 # Once the limit is reached Redis will close all the new connections sending
 548 # an error 'max number of clients reached'.
 549 #
 550 # 限制同时连接的客户数量,默认是10000
 551 # 当连接数超过这个值时,redis 将不再接收其他连接请求,客户端尝试连接时将收到 error 信息
 552 # maxclients 10000
 553 
 554 # Don't use more memory than the specified amount of bytes.
 555 # When the memory limit is reached Redis will try to remove keys
 556 # according to the eviction policy selected (see maxmemory-policy).
 557 #
 558 # If Redis can't remove keys according to the policy, or if the policy is
 559 # set to 'noeviction', Redis will start to reply with errors to commands
 560 # that would use more memory, like SET, LPUSH, and so on, and will continue
 561 # to reply to read-only commands like GET.
 562 #
 563 # This option is usually useful when using Redis as an LRU cache, or to set
 564 # a hard memory limit for an instance (using the 'noeviction' policy).
 565 #
 566 # WARNING: If you have slaves attached to an instance with maxmemory on,
 567 # the size of the output buffers needed to feed the slaves are subtracted
 568 # from the used memory count, so that network problems / resyncs will
 569 # not trigger a loop where keys are evicted, and in turn the output
 570 # buffer of slaves is full with DELs of keys evicted triggering the deletion
 571 # of more keys, and so forth until the database is completely emptied.
 572 #
 573 # In short... if you have slaves attached it is suggested that you set a lower
 574 # limit for maxmemory so that there is some free RAM on the system for slave
 575 # output buffers (but this is not needed if the policy is 'noeviction').
 576 #
 577 # 设置redis能够使用的最大内存。
 578 # 达到最大内存设置后,Redis会先尝试清除已到期或即将到期的Key(设置过expire信息的key)
 579 # 在删除时,按照过期时间进行删除,最早将要被过期的key将最先被删除
 580 # 如果已到期或即将到期的key删光,仍进行set操作,那么将返回错误
 581 # 此时redis将不再接收写请求,只接收get请求。
 582 # maxmemory的设置比较适合于把redis当作于类似memcached 的缓存来使用
 583 # maxmemory <bytes>
 584 
 585 # MAXMEMORY POLICY: how Redis will select what to remove when maxmemory
 586 # is reached. You can select among five behaviors:
 587 #
 588 # volatile-lru -> remove the key with an expire set using an LRU algorithm
 589 # allkeys-lru -> remove any key according to the LRU algorithm
 590 # volatile-random -> remove a random key with an expire set
 591 # allkeys-random -> remove a random key, any key
 592 # volatile-ttl -> remove the key with the nearest expire time (minor TTL)
 593 # noeviction -> don't expire at all, just return an error on write operations
 594 #
 595 # Note: with any of the above policies, Redis will return an error on write
 596 #       operations, when there are no suitable keys for eviction.
 597 #
 598 #       At the date of writing these commands are: set setnx setex append
 599 #       incr decr rpush lpush rpushx lpushx linsert lset rpoplpush sadd
 600 #       sinter sinterstore sunion sunionstore sdiff sdiffstore zadd zincrby
 601 #       zunionstore zinterstore hset hsetnx hmset hincrby incrby decrby
 602 #       getset mset msetnx exec sort
 603 #
 604 # The default is:
 605 #
 606 # maxmemory-policy noeviction
 607 
 608 # LRU and minimal TTL algorithms are not precise algorithms but approximated
 609 # algorithms (in order to save memory), so you can tune it for speed or
 610 # accuracy. For default Redis will check five keys and pick the one that was
 611 # used less recently, you can change the sample size using the following
 612 # configuration directive.
 613 #
 614 # The default of 5 produces good enough results. 10 Approximates very closely
 615 # true LRU but costs a bit more CPU. 3 is very fast but not very accurate.
 616 #
 617 # maxmemory-samples 5
 618 
 619 ############################## APPEND ONLY MODE ###############################
 620 
 621 # By default Redis asynchronously dumps the dataset on disk. This mode is
 622 # good enough in many applications, but an issue with the Redis process or
 623 # a power outage may result into a few minutes of writes lost (depending on
 624 # the configured save points).
 625 #
 626 # The Append Only File is an alternative persistence mode that provides
 627 # much better durability. For instance using the default data fsync policy
 628 # (see later in the config file) Redis can lose just one second of writes in a
 629 # dramatic event like a server power outage, or a single write if something
 630 # wrong with the Redis process itself happens, but the operating system is
 631 # still running correctly.
 632 #
 633 # AOF and RDB persistence can be enabled at the same time without problems.
 634 # If the AOF is enabled on startup Redis will load the AOF, that is the file
 635 # with the better durability guarantees.
 636 #
 637 # Please check http://redis.io/topics/persistence for more information.
 638 
 639 # redis 默认每次更新操作后会在后台异步的把数据库镜像备份到磁盘,但该备份非常耗时,且备份不宜太频繁
 640 # redis 同步数据文件是按上面save条件来同步的
 641 # 如果发生诸如拉闸限电、拔插头等状况,那么将造成比较大范围的数据丢失
 642 # 所以redis提供了另外一种更加高效的数据库备份及灾难恢复方式
 643 # 开启append only 模式后,redis 将每一次写操作请求都追加到appendonly.aof 文件中
 644 # redis重新启动时,会从该文件恢复出之前的状态。
 645 # 但可能会造成 appendonly.aof 文件过大,所以redis支持BGREWRITEAOF 指令,对appendonly.aof重新整理,默认是不开启的。
 646 
 647 appendonly no
 648 
 649 # The name of the append only file (default: "appendonly.aof")
 650 # 默认为appendonly.aof。
 651 appendfilename "appendonly.aof"
 652 
 653 # The fsync() call tells the Operating System to actually write data on disk
 654 # instead of waiting for more data in the output buffer. Some OS will really flush
 655 # data on disk, some other OS will just try to do it ASAP.
 656 #
 657 # Redis supports three different modes:
 658 #
 659 # no: don't fsync, just let the OS flush the data when it wants. Faster.
 660 # always: fsync after every write to the append only log. Slow, Safest.
 661 # everysec: fsync only one time every second. Compromise.
 662 #
 663 # The default is "everysec", as that's usually the right compromise between
 664 # speed and data safety. It's up to you to understand if you can relax this to
 665 # "no" that will let the operating system flush the output buffer when
 666 # it wants, for better performances (but if you can live with the idea of
 667 # some data loss consider the default persistence mode that's snapshotting),
 668 # or on the contrary, use "always" that's very slow but a bit safer than
 669 # everysec.
 670 #
 671 # More details please check the following article:
 672 # http://antirez.com/post/redis-persistence-demystified.html
 673 #
 674 # If unsure, use "everysec".
 675 
 676 # 设置对 appendonly.aof 文件进行同步的频率,有三种选择always、everysec、no,默认是everysec表示每秒同步一次。
 677 # always 表示每次有写操作都进行同步,everysec 表示对写操作进行累积,每秒同步一次。
 678 # no表示等操作系统进行数据缓存同步到磁盘,都进行同步,everysec 表示对写操作进行累积,每秒同步一次
 679 # appendfsync always
 680 # appendfsync everysec
 681 # appendfsync no
 682 
 683 # When the AOF fsync policy is set to always or everysec, and a background
 684 # saving process (a background save or AOF log background rewriting) is
 685 # performing a lot of I/O against the disk, in some Linux configurations
 686 # Redis may block too long on the fsync() call. Note that there is no fix for
 687 # this currently, as even performing fsync in a different thread will block
 688 # our synchronous write(2) call.
 689 #
 690 # In order to mitigate this problem it's possible to use the following option
 691 # that will prevent fsync() from being called in the main process while a
 692 # BGSAVE or BGREWRITEAOF is in progress.
 693 #
 694 # This means that while another child is saving, the durability of Redis is
 695 # the same as "appendfsync none". In practical terms, this means that it is
 696 # possible to lose up to 30 seconds of log in the worst scenario (with the
 697 # default Linux settings).
 698 #
 699 # If you have latency problems turn this to "yes". Otherwise leave it as
 700 # "no" that is the safest pick from the point of view of durability.
 701 # 指定是否在后台aof文件rewrite期间调用fsync,默认为no,表示要调用fsync(无论后台是否有子进程在刷盘)。Redis在后台写RDB文件或重写afo文件期间会存在大量磁盘IO,此时,在某些linux系统中,调用fsync可能会阻塞。
 702 no-appendfsync-on-rewrite yes
 703 
 704 # Automatic rewrite of the append only file.
 705 # Redis is able to automatically rewrite the log file implicitly calling
 706 # BGREWRITEAOF when the AOF log size grows by the specified percentage.
 707 #
 708 # This is how it works: Redis remembers the size of the AOF file after the
 709 # latest rewrite (if no rewrite has happened since the restart, the size of
 710 # the AOF at startup is used).
 711 #
 712 # This base size is compared to the current size. If the current size is
 713 # bigger than the specified percentage, the rewrite is triggered. Also
 714 # you need to specify a minimal size for the AOF file to be rewritten, this
 715 # is useful to avoid rewriting the AOF file even if the percentage increase
 716 # is reached but it is still pretty small.
 717 #
 718 # Specify a percentage of zero in order to disable the automatic AOF
 719 # rewrite feature.
 720 # 指定Redis重写aof文件的条件,默认为100,表示与上次rewrite的aof文件大小相比,当前aof文件增长量超过上次afo文件大小的100%时,就会触发background rewrite。若配置为0,则会禁用自动rewrite
 721 auto-aof-rewrite-percentage 100
 722 
 723 # 指定触发rewrite的aof文件大小。若aof文件小于该值,即使当前文件的增量比例达到auto-aof-rewrite-percentage的配置值,也不会触发自动rewrite。即这两个配置项同时满足时,才会触发rewrite。
 724 auto-aof-rewrite-min-size 64mb
 725 
 726 # An AOF file may be found to be truncated at the end during the Redis
 727 # startup process, when the AOF data gets loaded back into memory.
 728 # This may happen when the system where Redis is running
 729 # crashes, especially when an ext4 filesystem is mounted without the
 730 # data=ordered option (however this can't happen when Redis itself
 731 # crashes or aborts but the operating system still works correctly).
 732 #
 733 # Redis can either exit with an error when this happens, or load as much
 734 # data as possible (the default now) and start if the AOF file is found
 735 # to be truncated at the end. The following option controls this behavior.
 736 #
 737 # If aof-load-truncated is set to yes, a truncated AOF file is loaded and
 738 # the Redis server starts emitting a log to inform the user of the event.
 739 # Otherwise if the option is set to no, the server aborts with an error
 740 # and refuses to start. When the option is set to no, the user requires
 741 # to fix the AOF file using the "redis-check-aof" utility before to restart
 742 # the server.
 743 #
 744 # Note that if the AOF file will be found to be corrupted in the middle
 745 # the server will still exit with an error. This option only applies when
 746 # Redis will try to read more data from the AOF file but not enough bytes
 747 # will be found.
 748 aof-load-truncated yes
 749 
 750 ################################ LUA SCRIPTING  ###############################
 751 
 752 # Max execution time of a Lua script in milliseconds.
 753 #
 754 # If the maximum execution time is reached Redis will log that a script is
 755 # still in execution after the maximum allowed time and will start to
 756 # reply to queries with an error.
 757 #
 758 # When a long running script exceeds the maximum execution time only the
 759 # SCRIPT KILL and SHUTDOWN NOSAVE commands are available. The first can be
 760 # used to stop a script that did not yet called write commands. The second
 761 # is the only way to shut down the server in the case a write command was
 762 # already issued by the script but the user doesn't want to wait for the natural
 763 # termination of the script.
 764 #
 765 # Set it to 0 or a negative value for unlimited execution without warnings.
 766 # 一个Lua脚本最长的执行时间,单位为毫秒,如果为0或负数表示无限执行时间,默认为5000
 767 lua-time-limit 5000
 768 
 769 ################################ REDIS CLUSTER  ###############################
 770 #
 771 # ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 772 # WARNING EXPERIMENTAL: Redis Cluster is considered to be stable code, however
 773 # in order to mark it as "mature" we need to wait for a non trivial percentage
 774 # of users to deploy it in production.
 775 # ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 776 #
 777 # Normal Redis instances can't be part of a Redis Cluster; only nodes that are
 778 # started as cluster nodes can. In order to start a Redis instance as a
 779 # cluster node enable the cluster support uncommenting the following:
 780 #
 781 # cluster-enabled yes
 782 
 783 # Every cluster node has a cluster configuration file. This file is not
 784 # intended to be edited by hand. It is created and updated by Redis nodes.
 785 # Every Redis Cluster node requires a different cluster configuration file.
 786 # Make sure that instances running in the same system do not have
 787 # overlapping cluster configuration file names.
 788 #
 789 # cluster-config-file nodes-6379.conf
 790 
 791 # Cluster node timeout is the amount of milliseconds a node must be unreachable
 792 # for it to be considered in failure state.
 793 # Most other internal time limits are multiple of the node timeout.
 794 #
 795 # cluster-node-timeout 15000
 796 
 797 # A slave of a failing master will avoid to start a failover if its data
 798 # looks too old.
 799 #
 800 # There is no simple way for a slave to actually have a exact measure of
 801 # its "data age", so the following two checks are performed:
 802 #
 803 # 1) If there are multiple slaves able to failover, they exchange messages
 804 #    in order to try to give an advantage to the slave with the best
 805 #    replication offset (more data from the master processed).
 806 #    Slaves will try to get their rank by offset, and apply to the start
 807 #    of the failover a delay proportional to their rank.
 808 #
 809 # 2) Every single slave computes the time of the last interaction with
 810 #    its master. This can be the last ping or command received (if the master
 811 #    is still in the "connected" state), or the time that elapsed since the
 812 #    disconnection with the master (if the replication link is currently down).
 813 #    If the last interaction is too old, the slave will not try to failover
 814 #    at all.
 815 #
 816 # The point "2" can be tuned by user. Specifically a slave will not perform
 817 # the failover if, since the last interaction with the master, the time
 818 # elapsed is greater than:
 819 #
 820 #   (node-timeout * slave-validity-factor) + repl-ping-slave-period
 821 #
 822 # So for example if node-timeout is 30 seconds, and the slave-validity-factor
 823 # is 10, and assuming a default repl-ping-slave-period of 10 seconds, the
 824 # slave will not try to failover if it was not able to talk with the master
 825 # for longer than 310 seconds.
 826 #
 827 # A large slave-validity-factor may allow slaves with too old data to failover
 828 # a master, while a too small value may prevent the cluster from being able to
 829 # elect a slave at all.
 830 #
 831 # For maximum availability, it is possible to set the slave-validity-factor
 832 # to a value of 0, which means, that slaves will always try to failover the
 833 # master regardless of the last time they interacted with the master.
 834 # (However they'll always try to apply a delay proportional to their
 835 # offset rank).
 836 #
 837 # Zero is the only value able to guarantee that when all the partitions heal
 838 # the cluster will always be able to continue.
 839 #
 840 # cluster-slave-validity-factor 10
 841 
 842 # Cluster slaves are able to migrate to orphaned masters, that are masters
 843 # that are left without working slaves. This improves the cluster ability
 844 # to resist to failures as otherwise an orphaned master can't be failed over
 845 # in case of failure if it has no working slaves.
 846 #
 847 # Slaves migrate to orphaned masters only if there are still at least a
 848 # given number of other working slaves for their old master. This number
 849 # is the "migration barrier". A migration barrier of 1 means that a slave
 850 # will migrate only if there is at least 1 other working slave for its master
 851 # and so forth. It usually reflects the number of slaves you want for every
 852 # master in your cluster.
 853 #
 854 # Default is 1 (slaves migrate only if their masters remain with at least
 855 # one slave). To disable migration just set it to a very large value.
 856 # A value of 0 can be set but is useful only for debugging and dangerous
 857 # in production.
 858 #
 859 # cluster-migration-barrier 1
 860 
 861 # By default Redis Cluster nodes stop accepting queries if they detect there
 862 # is at least an hash slot uncovered (no available node is serving it).
 863 # This way if the cluster is partially down (for example a range of hash slots
 864 # are no longer covered) all the cluster becomes, eventually, unavailable.
 865 # It automatically returns available as soon as all the slots are covered again.
 866 #
 867 # However sometimes you want the subset of the cluster which is working,
 868 # to continue to accept queries for the part of the key space that is still
 869 # covered. In order to do so, just set the cluster-require-full-coverage
 870 # option to no.
 871 #
 872 # cluster-require-full-coverage yes
 873 
 874 # In order to setup your cluster make sure to read the documentation
 875 # available at http://redis.io web site.
 876 
 877 ################################## SLOW LOG ###################################
 878 
 879 # The Redis Slow Log is a system to log queries that exceeded a specified
 880 # execution time. The execution time does not include the I/O operations
 881 # like talking with the client, sending the reply and so forth,
 882 # but just the time needed to actually execute the command (this is the only
 883 # stage of command execution where the thread is blocked and can not serve
 884 # other requests in the meantime).
 885 #
 886 # You can configure the slow log with two parameters: one tells Redis
 887 # what is the execution time, in microseconds, to exceed in order for the
 888 # command to get logged, and the other parameter is the length of the
 889 # slow log. When a new command is logged the oldest one is removed from the
 890 # queue of logged commands.
 891 
 892 # The following time is expressed in microseconds, so 1000000 is equivalent
 893 # to one second. Note that a negative number disables the slow log, while
 894 # a value of zero forces the logging of every command.
 895 slowlog-log-slower-than 10000
 896 
 897 # There is no limit to this length. Just be aware that it will consume memory.
 898 # You can reclaim memory used by the slow log with SLOWLOG RESET.
 899 slowlog-max-len 128
 900 
 901 ################################ LATENCY MONITOR ##############################
 902 
 903 # The Redis latency monitoring subsystem samples different operations
 904 # at runtime in order to collect data related to possible sources of
 905 # latency of a Redis instance.
 906 #
 907 # Via the LATENCY command this information is available to the user that can
 908 # print graphs and obtain reports.
 909 #
 910 # The system only logs operations that were performed in a time equal or
 911 # greater than the amount of milliseconds specified via the
 912 # latency-monitor-threshold configuration directive. When its value is set
 913 # to zero, the latency monitor is turned off.
 914 #
 915 # By default latency monitoring is disabled since it is mostly not needed
 916 # if you don't have latency issues, and collecting data has a performance
 917 # impact, that while very small, can be measured under big load. Latency
 918 # monitoring can easily be enabled at runtime using the command
 919 # "CONFIG SET latency-monitor-threshold <milliseconds>" if needed.
 920 latency-monitor-threshold 0
 921 
 922 ############################# EVENT NOTIFICATION ##############################
 923 
 924 # Redis can notify Pub/Sub clients about events happening in the key space.
 925 # This feature is documented at http://redis.io/topics/notifications
 926 #
 927 # For instance if keyspace events notification is enabled, and a client
 928 # performs a DEL operation on key "foo" stored in the Database 0, two
 929 # messages will be published via Pub/Sub:
 930 #
 931 # PUBLISH [email protected]__:foo del
 932 # PUBLISH [email protected]__:del foo
 933 #
 934 # It is possible to select the events that Redis will notify among a set
 935 # of classes. Every class is identified by a single character:
 936 #
 937 #  K     Keyspace events, published with [email protected]<db>__ prefix.
 938 #  E     Keyevent events, published with [email protected]<db>__ prefix.
 939 #  g     Generic commands (non-type specific) like DEL, EXPIRE, RENAME, ...
 940 #  $     String commands
 941 #  l     List commands
 942 #  s     Set commands
 943 #  h     Hash commands
 944 #  z     Sorted set commands
 945 #  x     Expired events (events generated every time a key expires)
 946 #  e     Evicted events (events generated when a key is evicted for maxmemory)
 947 #  A     Alias for g$lshzxe, so that the "AKE" string means all the events.
 948 #
 949 #  The "notify-keyspace-events" takes as argument a string that is composed
 950 #  of zero or multiple characters. The empty string means that notifications
 951 #  are disabled.
 952 #
 953 #  Example: to enable list and generic events, from the point of view of the
 954 #           event name, use:
 955 #
 956 #  notify-keyspace-events Elg
 957 #
 958 #  Example 2: to get the stream of the expired keys subscribing to channel
 959 #             name [email protected]__:expired use:
 960 #
 961 #  notify-keyspace-events Ex
 962 #
 963 #  By default all notifications are disabled because most users don't need
 964 #  this feature and the feature has some overhead. Note that if you don't
 965 #  specify at least one of K or E, no events will be delivered.
 966 notify-keyspace-events ""
 967 
 968 ############################### ADVANCED CONFIG ###############################
 969 
 970 # Hashes are encoded using a memory efficient data structure when they have a
 971 # small number of entries, and the biggest entry does not exceed a given
 972 # threshold. These thresholds can be configured using the following directives.
 973 # 当hash中包含超过指定元素个数并且最大的元素没有超过临界时,
 974 # hash将以一种特殊的编码方式(大大减少内存使用)来存储,这里可以设置这两个临界值
 975 hash-max-ziplist-entries 512
 976 hash-max-ziplist-value 64
 977 
 978 # Similarly to hashes, small lists are also encoded in a special way in order
 979 # to save a lot of space. The special representation is only used when
 980 # you are under the following limits:
 981 # list数据类型多少节点以下会采用去指针的紧凑存储格式。
 982 # list数据类型节点值大小小于多少字节会采用紧凑存储格式。
 983 list-max-ziplist-entries 512
 984 list-max-ziplist-value 64
 985 
 986 # Sets have a special encoding in just one case: when a set is composed
 987 # of just strings that happen to be integers in radix 10 in the range
 988 # of 64 bit signed integers.
 989 # The following configuration setting sets the limit in the size of the
 990 # set in order to use this special memory saving encoding.
 991 # set数据类型内部数据如果全部是数值型,且包含多少节点以下会采用紧凑格式存储。
 992 set-max-intset-entries 512
 993 
 994 # Similarly to hashes and lists, sorted sets are also specially encoded in
 995 # order to save a lot of space. This encoding is only used when the length and
 996 # elements of a sorted set are below the following limits:
 997 
 998 # zsort数据类型多少节点以下会采用去指针的紧凑存储格式。
 999 # zsort数据类型节点值大小小于多少字节会采用紧凑存储格式。
1000 zset-max-ziplist-entries 128
1001 zset-max-ziplist-value 64
1002 
1003 # HyperLogLog sparse representation bytes limit. The limit includes the
1004 # 16 bytes header. When an HyperLogLog using the sparse representation crosses
1005 # this limit, it is converted into the dense representation.
1006 #
1007 # A value greater than 16000 is totally useless, since at that point the
1008 # dense representation is more memory efficient.
1009 #
1010 # The suggested value is ~ 3000 in order to have the benefits of
1011 # the space efficient encoding without slowing down too much PFADD,
1012 # which is O(N) with the sparse encoding. The value can be raised to
1013 # ~ 10000 when CPU is not a concern, but space is, and the data set is
1014 # composed of many HyperLogLogs with cardinality in the 0 - 15000 range.
1015 hll-sparse-max-bytes 3000
1016 
1017 # Active rehashing uses 1 millisecond every 100 milliseconds of CPU time in
1018 # order to help rehashing the main Redis hash table (the one mapping top-level
1019 # keys to values). The hash table implementation Redis uses (see dict.c)
1020 # performs a lazy rehashing: the more operation you run into a hash table
1021 # that is rehashing, the more rehashing "steps" are performed, so if the
1022 # server is idle the rehashing is never complete and some more memory is used
1023 # by the hash table.
1024 #
1025 # The default is to use this millisecond 10 times every second in order to
1026 # actively rehash the main dictionaries, freeing memory when possible.
1027 #
1028 # If unsure:
1029 # use "activerehashing no" if you have hard latency requirements and it is
1030 # not a good thing in your environment that Redis can reply from time to time
1031 # to queries with 2 milliseconds delay.
1032 #
1033 # use "activerehashing yes" if you don't have such hard requirements but
1034 # want to free memory asap when possible.
1035 
1036 # Redis将在每100毫秒时使用1毫秒的CPU时间来对redis的hash表进行重新hash,可以降低内存的使用
1037 # 当你的使用场景中,有非常严格的实时性需要,不能够接受Redis时不时的对请求有2毫秒的延迟的话,把这项配置为no。
1038 # 如果没有这么严格的实时性要求,可以设置为yes,以便能够尽可能快的释放内存
1039 activerehashing yes
1040 
1041 # The client output buffer limits can be used to force disconnection of clients
1042 # that are not reading data from the server fast enough for some reason (a
1043 # common reason is that a Pub/Sub client can't consume messages as fast as the
1044 # publisher can produce them).
1045 #
1046 # The limit can be set differently for the three different classes of clients:
1047 #
1048 # normal -> normal clients including MONITOR clients
1049 # slave  -> slave clients
1050 # pubsub -> clients subscribed to at least one pubsub channel or pattern
1051 #
1052 # The syntax of every client-output-buffer-limit directive is the following:
1053 #
1054 # client-output-buffer-limit <class> <hard limit> <soft limit> <soft seconds>
1055 #
1056 # A client is immediately disconnected once the hard limit is reached, or if
1057 # the soft limit is reached and remains reached for the specified number of
1058 # seconds (continuously).
1059 # So for instance if the hard limit is 32 megabytes and the soft limit is
1060 # 16 megabytes / 10 seconds, the client will get disconnected immediately
1061 # if the size of the output buffers reach 32 megabytes, but will also get
1062 # disconnected if the client reaches 16 megabytes and continuously overcomes
1063 # the limit for 10 seconds.
1064 #
1065 # By default normal clients are not limited because they don't receive data
1066 # without asking (in a push way), but just after a request, so only
1067 # asynchronous clients may create a scenario where data is requested faster
1068 # than it can read.
1069 #
1070 # Instead there is a default limit for pubsub and slave clients, since
1071 # subscribers and slaves receive data in a push fashion.
1072 #
1073 # Both the hard or the soft limit can be disabled by setting them to zero.
1074 client-output-buffer-limit normal 0 0 0
1075 client-output-buffer-limit slave 256mb 64mb 60
1076 client-output-buffer-limit pubsub 32mb 8mb 60
1077 
1078 # Redis calls an internal function to perform many background tasks, like
1079 # closing connections of clients in timeout, purging expired keys that are
1080 # never requested, and so forth.
1081 #
1082 # Not all tasks are performed with the same frequency, but Redis checks for
1083 # tasks to perform according to the specified "hz" value.
1084 #
1085 # By default "hz" is set to 10. Raising the value will use more CPU when
1086 # Redis is idle, but at the same time will make Redis more responsive when
1087 # there are many keys expiring at the same time, and timeouts may be
1088 # handled with more precision.
1089 #
1090 # The range is between 1 and 500, however a value over 100 is usually not
1091 # a good idea. Most users should use the default of 10 and raise this up to
1092 # 100 only in environments where very low latency is required.
1093 hz 10
1094 
1095 # When a child rewrites the AOF file, if the following option is enabled
1096 # the file will be fsync-ed every 32 MB of data generated. This is useful
1097 # in order to commit the file to the disk more incrementally and avoid
1098 # big latency spikes.
1099 # aof rewrite过程中,是否采取增量文件同步策略,默认为“yes”。 rewrite过程中,每32M数据进行一次文件同步,这样可以减少aof大文件写入对磁盘的操作次数
1100 aof-rewrite-incremental-fsync yes
1101 
1102 
1103 # redis数据存储
1104 redis的存储分为内存存储、磁盘存储和log文件三部分,配置文件中有三个参数对其进行配置。
1105 save seconds updates,save配置,指出在多长时间内,有多少次更新操作,就将数据同步到数据文件。可多个条件配合,默认配置了三个条件。
1106 appendonly yes/no ,appendonly配置,指出是否在每次更新操作后进行日志记录,如果不开启,可能会在断电时导致一段时间内的数据丢失。因为redis本身同步数据文件是按上面的save条件来同步的,所以有的数据会在一段时间内只存在于内存中。
1107 appendfsync no/always/everysec ,appendfsync配置,no表示等操作系统进行数据缓存同步到磁盘,always表示每次更新操作后手动调用fsync()将数据写到磁盘,everysec表示每秒同步一次。

 

##redis配置详解
# Redis configuration file example.## Note that in order to read the configuration file, Redis must be# started with the file path as first argument:## ./redis-server /path/to/redis.conf
# Note on units: when memory size is needed, it is possible to specify# it in the usual form of 1k 5GB 4M and so forth:## 1k => 1000 bytes# 1kb => 1024 bytes# 1m => 1000000 bytes# 1mb => 1024*1024 bytes# 1g => 1000000000 bytes# 1gb => 1024*1024*1024 bytes## units are case insensitive so 1GB 1Gb 1gB are all the same.
################################## INCLUDES ##################################################################### 包含     ###################################
# Include one or more other config files here.  This is useful if you# have a standard template that goes to all Redis servers but also need# to customize a few per-server settings.  Include files can include# other files, so use this wisely.## Notice option "include" won't be rewritten by command "CONFIG REWRITE"# from admin or Redis Sentinel. Since Redis always uses the last processed# line as value of a configuration directive, you'd better put includes# at the beginning of this file to avoid overwriting config change at runtime.## If instead you are interested in using includes to override configuration# options, it is better to use include as the last line.## 假如说你有一个可用于所有的 redis server 的标准配置模板,# 但针对某些 server 又需要一些个性化的设置,# 你可以使用 include 来包含一些其他的配置文件,这对你来说是非常有用的。## 但是要注意哦,include 是不能被 config rewrite 命令改写的# 由于 redis 总是以最后的加工线作为一个配置指令值,所以你最好是把 include 放在这个文件的最前面,# 以避免在运行时覆盖配置的改变,相反,你就把它放在后面# include /path/to/local.conf# include /path/to/other.conf
################################ GENERAL  ##################################################################### 常用     #####################################
# By default Redis does not run as a daemon. Use 'yes' if you need it.# Note that Redis will write a pid file in /var/run/redis.pid when daemonized.# 默认情况下 redis 不是作为守护进程运行的,如果你想让它在后台运行,你就把它改成 yes。# 当redis作为守护进程运行的时候,它会写一个 pid 到 /var/run/redis.pid 文件里面。daemonize yes
# When running daemonized, Redis writes a pid file in /var/run/redis.pid by# default. You can specify a custom pid file location here.# 当 Redis 以守护进程的方式运行的时候,Redis 默认会把 pid 文件放在/var/run/redis.pid# 可配置到其他地址,当运行多个 redis 服务时,需要指定不同的 pid 文件和端口# 指定存储Redis进程号的文件路径pidfile /var/run/redis.pid
# Accept connections on the specified port, default is 6379.# If port 0 is specified Redis will not listen on a TCP socket.# 端口,默认端口是6379,生产环境中建议更改端口号,安全性更高# 如果你设为 0 ,redis 将不在 socket 上监听任何客户端连接。port 9966
# TCP listen() backlog.## In high requests-per-second environments you need an high backlog in order# to avoid slow clients connections issues. Note that the Linux kernel# will silently truncate it to the value of /proc/sys/net/core/somaxconn so# make sure to raise both the value of somaxconn and tcp_max_syn_backlog# in order to get the desired effect.# TCP 监听的最大容纳数量# 此参数确定了TCP连接中已完成队列(完成三次握手之后)的长度,# 当系统并发量大并且客户端速度缓慢的时候,你需要把这个值调高以避免客户端连接缓慢的问题。# Linux 内核会一声不响的把这个值缩小成 /proc/sys/net/core/somaxconn 对应的值,默认是511,而Linux的默认参数值是128。# 所以可以将这二个参数一起参考设定,你以便达到你的预期。#  tcp-backlog 511
# By default Redis listens for connections from all the network interfaces# available on the server. It is possible to listen to just one or multiple# interfaces using the "bind" configuration directive, followed by one or# more IP addresses.## Examples:## bind 192.168.1.100 10.0.0.1# 有时候为了安全起见,redis一般都是监听127.0.0.1 但是有时候又有同网段能连接的需求,当然可以绑定0.0.0.0 用iptables来控制访问权限,或者设置redis访问密码来保证数据安全
# 不设置将处理所有请求,建议生产环境中设置,有个误区:bind是用来限制外网IP访问的,其实不是,限制外网ip访问可以通过iptables;如:-A INPUT -s 10.10.1.0/24 -p tcp -m state --state NEW -m tcp --dport 9966 -j ACCEPT ;# 实际上,bind ip 绑定的是redis所在服务器网卡的ip,当然127.0.0.1也是可以的#如果绑定一个外网ip,就会报错:Creating Server TCP listening socket xxx.xxx.xxx.xxx:9966: bind: Cannot assign requested address
# bind 127.0.0.1bind 127.0.0.1 10.10.1.3
# 假设绑定是以上ip,使用 netstat -anp|grep 9966 会发现,这两个ip被bind,其中10.10.1.3是服务器网卡的ip# tcp        0      0 10.10.1.3:9966         0.0.0.0:*                   LISTEN      11188/redis-server  # tcp        0      0 127.0.0.1:9966         0.0.0.0:*                   LISTEN      11188/redis-server 

# Specify the path for the Unix socket that will be used to listen for# incoming connections. There is no default, so Redis will not listen# on a unix socket when not specified.## unixsocket /tmp/redis.sock# unixsocketperm 700
# Close the connection after a client is idle for N seconds (0 to disable)# 客户端和Redis服务端的连接超时时间,默认是0,表示永不超时。timeout 0
# TCP keepalive.## If non-zero, use SO_KEEPALIVE to send TCP ACKs to clients in absence# of communication. This is useful for two reasons:## 1) Detect dead peers.# 2) Take the connection alive from the point of view of network#    equipment in the middle.## On Linux, the specified value (in seconds) is the period used to send ACKs.# Note that to close the connection the double of the time is needed.# On other kernels the period depends on the kernel configuration.## A reasonable value for this option is 60 seconds.
# tcp 心跳包。## 如果设置为非零,则在与客户端缺乏通讯的时候使用 SO_KEEPALIVE 发送 tcp acks 给客户端。# 这个之所有有用,主要由两个原因:## 1) 防止死的 peers# 2) Take the connection alive from the point of view of network#    equipment in the middle.## 推荐一个合理的值就是60秒tcp-keepalive 0
# Specify the server verbosity level.# This can be one of:# debug (a lot of information, useful for development/testing)# verbose (many rarely useful info, but not a mess like the debug level)# notice (moderately verbose, what you want in production probably)# warning (only very important / critical messages are logged)# 日志记录等级,4个可选值debug,verbose,notice,warning# 可以是下面的这些值:# debug (适用于开发或测试阶段)# verbose (many rarely useful info, but not a mess like the debug level)# notice (适用于生产环境)# warning (仅仅一些重要的消息被记录)loglevel notice
# Specify the log file name. Also the empty string can be used to force# Redis to log on the standard output. Note that if you use standard# output for logging but daemonize, logs will be sent to /dev/null#配置 log 文件地址,默认打印在命令行终端的窗口上,也可设为/dev/null屏蔽日志、logfile "/data/logs/redis/redis.log"
# To enable logging to the system logger, just set 'syslog-enabled' to yes,# and optionally update the other syslog parameters to suit your needs.# 要想把日志记录到系统日志,就把它改成 yes,# 也可以可选择性的更新其他的syslog 参数以达到你的要求# syslog-enabled no
# Specify the syslog identity.# 设置 syslog 的 identity。# syslog-ident redis
# Specify the syslog facility. Must be USER or between LOCAL0-LOCAL7.# syslog-facility local0
# Set the number of databases. The default database is DB 0, you can select# a different one on a per-connection basis using SELECT <dbid> where# dbid is a number between 0 and 'databases'-1# 可用的数据库数,默认值为16,默认数据库为0,数据库范围在0-(database-1)之间databases 16
################################ SNAPSHOTTING  ################################################################ 快照          ################################## Save the DB on disk:##   save <seconds> <changes>##   Will save the DB if both the given number of seconds and the given#   number of write operations against the DB occurred.##   In the example below the behaviour will be to save:#   after 900 sec (15 min) if at least 1 key changed#   after 300 sec (5 min) if at least 10 keys changed#   after 60 sec if at least 10000 keys changed##   Note: you can disable saving completely by commenting out all "save" lines.##   It is also possible to remove all the previously configured save#   points by adding a save directive with a single empty string argument#   like in the following example:##   save ""# 在 900 秒内最少有 1 个 key 被改动,或者 300 秒内最少有 10 个 key 被改动,又或者 60 秒内最少有 1000 个 key 被改动,以上三个条件随便满足一个,就触发一次保存操作。
#    if(在60秒之内有10000个keys发生变化时){#      进行镜像备份#    }else if(在300秒之内有10个keys发生了变化){#      进行镜像备份#    }else if(在900秒之内有1个keys发生了变化){#      进行镜像备份#    }
save 900 1save 300 10save 60 10000
# By default Redis will stop accepting writes if RDB snapshots are enabled# (at least one save point) and the latest background save failed.# This will make the user aware (in a hard way) that data is not persisting# on disk properly, otherwise chances are that no one will notice and some#:/ disaster will happen.## If the background saving process will start working again Redis will# automatically allow writes again.## However if you have setup your proper monitoring of the Redis server# and persistence, you may want to disable this feature so that Redis will# continue to work as usual even if there are problems with disk,# permissions, and so forth.# 默认情况下,如果 redis 最后一次的后台保存失败,redis 将停止接受写操作,# 这样以一种强硬的方式让用户知道数据不能正确的持久化到磁盘,# 否则就会没人注意到灾难的发生。## 如果后台保存进程重新启动工作了,redis 也将自动的允许写操作。## 然而你要是安装了靠谱的监控,你可能不希望 redis 这样做,那你就改成 no 好stop-writes-on-bgsave-error yes
# Compress string objects using LZF when dump .rdb databases?# For default that's set to 'yes' as it's almost always a win.# If you want to save some CPU in the saving child set it to 'no' but# the dataset will likely be bigger if you have compressible values or keys.# 在进行备份时,是否进行压缩# 是否在 dump .rdb 数据库的时候使用 LZF 压缩字符串# 默认都设为 yes# 如果你希望保存子进程节省点 cpu ,你就设置它为 no ,# 不过这个数据集可能就会比较大rdbcompression yes
# Since version 5 of RDB a CRC64 checksum is placed at the end of the file.# This makes the format more resistant to corruption but there is a performance# hit to pay (around 10%) when saving and loading RDB files, so you can disable it# for maximum performances.## RDB files created with checksum disabled have a checksum of zero that will# tell the loading code to skip the check.    # 读取和写入的时候是否支持CRC64校验,默认是开启的rdbchecksum yes
# The filename where to dump the DB# 备份文件的文件名dbfilename dump.rdb
# The working directory.## The DB will be written inside this directory, with the filename specified# above using the 'dbfilename' configuration directive.## The Append Only File will also be created inside this directory.## Note that you must specify a directory here, not a file name.# 数据库备份的文件放置的路径# 路径跟文件名分开配置是因为 Redis 备份时,先会将当前数据库的状态写入到一个临时文件# 等备份完成时,再把该临时文件替换为上面所指定的文件# 而临时文件和上面所配置的备份文件都会放在这个指定的路径当中# 默认值为 ./dir /data/data/redis/
################################# REPLICATION ################################################################## 主从复制    ################################## Master-Slave replication. Use slaveof to make a Redis instance a copy of# another Redis server. A few things to understand ASAP about Redis replication.## 1) Redis replication is asynchronous, but you can configure a master to#    stop accepting writes if it appears to be not connected with at least#    a given number of slaves.# 2) Redis slaves are able to perform a partial resynchronization with the#    master if the replication link is lost for a relatively small amount of#    time. You may want to configure the replication backlog size (see the next#    sections of this file) with a sensible value depending on your needs.# 3) Replication is automatic and does not need user intervention. After a#    network partition slaves automatically try to reconnect to masters#    and resynchronize with them.## 设置该数据库为其他数据库的从数据库# slaveof <masterip> <masterport> 当本机为从服务时,设置主服务的IP及端口# slaveof <masterip> <masterport>
# If the master is password protected (using the "requirepass" configuration# directive below) it is possible to tell the slave to authenticate before# starting the replication synchronization process, otherwise the master will# refuse the slave request.## 指定与主数据库连接时需要的密码验证# masterauth <master-password> 当本机为从服务时,设置访问master服务器的密码# masterauth <master-password>
# When a slave loses its connection with the master, or when the replication# is still in progress, the slave can act in two different ways:## 1) if slave-serve-stale-data is set to 'yes' (the default) the slave will#    still reply to client requests, possibly with out of date data, or the#    data set may just be empty if this is the first synchronization.## 2) if slave-serve-stale-data is set to 'no' the slave will reply with#    an error "SYNC with master in progress" to all the kind of commands#    but to INFO and SLAVEOF.## 当slave服务器和master服务器失去连接后,或者当数据正在复制传输的时候,如果此参数值设置“yes”,slave服务器可以继续接受客户端的请求,否则,会返回给请求的客户端如下信息“SYNC with master in progress”,除了INFO,SLAVEOF这两个命令slave-serve-stale-data yes
# You can configure a slave instance to accept writes or not. Writing against# a slave instance may be useful to store some ephemeral data (because data# written on a slave will be easily deleted after resync with the master) but# may also cause problems if clients are writing to it because of a# misconfiguration.## Since Redis 2.6 by default slaves are read-only.## Note: read only slaves are not designed to be exposed to untrusted clients# on the internet. It's just a protection layer against misuse of the instance.# Still a read only slave exports by default all the administrative commands# such as CONFIG, DEBUG, and so forth. To a limited extent you can improve# security of read only slaves using 'rename-command' to shadow all the# administrative / dangerous commands.# 是否允许slave服务器节点只提供读服务slave-read-only yes
# Replication SYNC strategy: disk or socket.## -------------------------------------------------------# WARNING: DISKLESS REPLICATION IS EXPERIMENTAL CURRENTLY# -------------------------------------------------------## New slaves and reconnecting slaves that are not able to continue the replication# process just receiving differences, need to do what is called a "full# synchronization". An RDB file is transmitted from the master to the slaves.# The transmission can happen in two different ways:## 1) Disk-backed: The Redis master creates a new process that writes the RDB#                 file on disk. Later the file is transferred by the parent#                 process to the slaves incrementally.# 2) Diskless: The Redis master creates a new process that directly writes the#              RDB file to slave sockets, without touching the disk at all.## With disk-backed replication, while the RDB file is generated, more slaves# can be queued and served with the RDB file as soon as the current child producing# the RDB file finishes its work. With diskless replication instead once# the transfer starts, new slaves arriving will be queued and a new transfer# will start when the current one terminates.## When diskless replication is used, the master waits a configurable amount of# time (in seconds) before starting the transfer in the hope that multiple slaves# will arrive and the transfer can be parallelized.## With slow disks and fast (large bandwidth) networks, diskless replication# works better.repl-diskless-sync no
# When diskless replication is enabled, it is possible to configure the delay# the server waits in order to spawn the child that transfers the RDB via socket# to the slaves.## This is important since once the transfer starts, it is not possible to serve# new slaves arriving, that will be queued for the next RDB transfer, so the server# waits a delay in order to let more slaves arrive.## The delay is specified in seconds, and by default is 5 seconds. To disable# it entirely just set it to 0 seconds and the transfer will start ASAP.repl-diskless-sync-delay 5
# Slaves send PINGs to server in a predefined interval. It's possible to change# this interval with the repl_ping_slave_period option. The default value is 10# seconds.## Slaves 在一个预定义的时间间隔内发送 ping 命令到 server 。# 你可以改变这个时间间隔。默认为 10 秒。# repl-ping-slave-period 10
# The following option sets the replication timeout for:## 1) Bulk transfer I/O during SYNC, from the point of view of slave.# 2) Master timeout from the point of view of slaves (data, pings).# 3) Slave timeout from the point of view of masters (REPLCONF ACK pings).## It is important to make sure that this value is greater than the value# specified for repl-ping-slave-period otherwise a timeout will be detected# every time there is low traffic between the master and the slave.## 设置主从复制过期时间# 这个值一定要比 repl-ping-slave-period 大# repl-timeout 60
# Disable TCP_NODELAY on the slave socket after SYNC?## If you select "yes" Redis will use a smaller number of TCP packets and# less bandwidth to send data to slaves. But this can add a delay for# the data to appear on the slave side, up to 40 milliseconds with# Linux kernels using a default configuration.## If you select "no" the delay for data to appear on the slave side will# be reduced but more bandwidth will be used for replication.## By default we optimize for low latency, but in very high traffic conditions# or when the master and slaves are many hops away, turning this to "yes" may# be a good idea.# 指定向slave同步数据时,是否禁用socket的NO_DELAY选 项。若配置为“yes”,则禁用NO_DELAY,则TCP协议栈会合并小包统一发送,这样可以减少主从节点间的包数量并节省带宽,但会增加数据同步到 slave的时间。若配置为“no”,表明启用NO_DELAY,则TCP协议栈不会延迟小包的发送时机,这样数据同步的延时会减少,但需要更大的带宽。 通常情况下,应该配置为no以降低同步延时,但在主从节点间网络负载已经很高的情况下,可以配置为yes。repl-disable-tcp-nodelay no
# Set the replication backlog size. The backlog is a buffer that accumulates# slave data when slaves are disconnected for some time, so that when a slave# wants to reconnect again, often a full resync is not needed, but a partial# resync is enough, just passing the portion of data the slave missed while# disconnected.## The bigger the replication backlog, the longer the time the slave can be# disconnected and later be able to perform a partial resynchronization.## The backlog is only allocated once there is at least a slave connected.## 设置主从复制容量大小。这个 backlog 是一个用来在 slaves 被断开连接时# 存放 slave 数据的 buffer,所以当一个 slave 想要重新连接,通常不希望全部重新同步,# 只是部分同步就够了,仅仅传递 slave 在断开连接时丢失的这部分数据。## The biggest the replication backlog, the longer the time the slave can be# disconnected and later be able to perform a partial resynchronization.# 这个值越大,salve 可以断开连接的时间就越长。
# repl-backlog-size 1mb
# After a master has no longer connected slaves for some time, the backlog# will be freed. The following option configures the amount of seconds that# need to elapse, starting from the time the last slave disconnected, for# the backlog buffer to be freed.## A value of 0 means to never release the backlog.## 在某些时候,master 不再连接 slaves,backlog 将被释放。# 如果设置为 0 ,意味着绝不释放 backlog 。# repl-backlog-ttl 3600
# The slave priority is an integer number published by Redis in the INFO output.# It is used by Redis Sentinel in order to select a slave to promote into a# master if the master is no longer working correctly.## A slave with a low priority number is considered better for promotion, so# for instance if there are three slaves with priority 10, 100, 25 Sentinel will# pick the one with priority 10, that is the lowest.## However a special priority of 0 marks the slave as not able to perform the# role of master, so a slave with priority of 0 will never be selected by# Redis Sentinel for promotion.## By default the priority is 100.# 指定slave的优先级。在不只1个slave存在的部署环境下,当master宕机时,Redis# Sentinel会将priority值最小的slave提升为master。# 这个值越小,就越会被优先选中,需要注意的是,# 若该配置项为0,则对应的slave永远不会自动提升为master。slave-priority 100
# It is possible for a master to stop accepting writes if there are less than# N slaves connected, having a lag less or equal than M seconds.## The N slaves need to be in "online" state.## The lag in seconds, that must be <= the specified value, is calculated from# the last ping received from the slave, that is usually sent every second.## This option does not GUARANTEE that N replicas will accept the write, but# will limit the window of exposure for lost writes in case not enough slaves# are available, to the specified number of seconds## For example to require at least 3 slaves with a lag <= 10 seconds use:## min-slaves-to-write 3# min-slaves-max-lag 10## Setting one or the other to 0 disables the feature.## By default min-slaves-to-write is set to 0 (feature disabled) and# min-slaves-max-lag is set to 10.
################################## SECURITY ##################################################################### 安全     ###################################
# Require clients to issue AUTH <PASSWORD> before processing any other# commands.  This might be useful in environments in which you do not trust# others with access to the host running redis-server.## This should stay commented out for backward compatibility and because most# people do not need auth (e.g. they run their own servers).## Warning: since Redis is pretty fast an outside user can try up to# 150k passwords per second against a good box. This means that you should# use a very strong password otherwise it will be very easy to break.## 设置连接redis的密码# redis速度相当快,一个外部用户在一秒钟进行150K次密码尝试,需指定强大的密码来防止暴力破解requirepass set_enough_strong_passwd
# Command renaming.## It is possible to change the name of dangerous commands in a shared# environment. For instance the CONFIG command may be renamed into something# hard to guess so that it will still be available for internal-use tools# but not available for general clients.## Example:## rename-command CONFIG b840fc02d524045429941cc15f59e41cb7be6c52## It is also possible to completely kill a command by renaming it into# an empty string:## rename-command CONFIG ""## Please note that changing the name of commands that are logged into the# AOF file or transmitted to slaves may cause problems.# 重命名一些高危命令,用来禁止高危命令rename-command FLUSHALL ZYzv6FOBdwflW2nXrename-command CONFIG aI7zwm1GDzMMrEirename-command EVAL S9UHPKEpSvUJMMrename-command FLUSHDB D60FPVDJuip7gy6l
################################### LIMITS ####################################################################### 限制   ####################################
# Set the max number of connected clients at the same time. By default# this limit is set to 10000 clients, however if the Redis server is not# able to configure the process file limit to allow for the specified limit# the max number of allowed clients is set to the current file limit# minus 32 (as Redis reserves a few file descriptors for internal uses).## Once the limit is reached Redis will close all the new connections sending# an error 'max number of clients reached'.## 限制同时连接的客户数量,默认是10000# 当连接数超过这个值时,redis 将不再接收其他连接请求,客户端尝试连接时将收到 error 信息# maxclients 10000
# Don't use more memory than the specified amount of bytes.# When the memory limit is reached Redis will try to remove keys# according to the eviction policy selected (see maxmemory-policy).## If Redis can't remove keys according to the policy, or if the policy is# set to 'noeviction', Redis will start to reply with errors to commands# that would use more memory, like SET, LPUSH, and so on, and will continue# to reply to read-only commands like GET.## This option is usually useful when using Redis as an LRU cache, or to set# a hard memory limit for an instance (using the 'noeviction' policy).## WARNING: If you have slaves attached to an instance with maxmemory on,# the size of the output buffers needed to feed the slaves are subtracted# from the used memory count, so that network problems / resyncs will# not trigger a loop where keys are evicted, and in turn the output# buffer of slaves is full with DELs of keys evicted triggering the deletion# of more keys, and so forth until the database is completely emptied.## In short... if you have slaves attached it is suggested that you set a lower# limit for maxmemory so that there is some free RAM on the system for slave# output buffers (but this is not needed if the policy is 'noeviction').## 设置redis能够使用的最大内存。# 达到最大内存设置后,Redis会先尝试清除已到期或即将到期的Key(设置过expire信息的key)# 在删除时,按照过期时间进行删除,最早将要被过期的key将最先被删除# 如果已到期或即将到期的key删光,仍进行set操作,那么将返回错误# 此时redis将不再接收写请求,只接收get请求。# maxmemory的设置比较适合于把redis当作于类似memcached 的缓存来使用# maxmemory <bytes>
# MAXMEMORY POLICY: how Redis will select what to remove when maxmemory# is reached. You can select among five behaviors:## volatile-lru -> remove the key with an expire set using an LRU algorithm# allkeys-lru -> remove any key according to the LRU algorithm# volatile-random -> remove a random key with an expire set# allkeys-random -> remove a random key, any key# volatile-ttl -> remove the key with the nearest expire time (minor TTL)# noeviction -> don't expire at all, just return an error on write operations## Note: with any of the above policies, Redis will return an error on write#       operations, when there are no suitable keys for eviction.##       At the date of writing these commands are: set setnx setex append#       incr decr rpush lpush rpushx lpushx linsert lset rpoplpush sadd#       sinter sinterstore sunion sunionstore sdiff sdiffstore zadd zincrby#       zunionstore zinterstore hset hsetnx hmset hincrby incrby decrby#       getset mset msetnx exec sort## The default is:## maxmemory-policy noeviction
# LRU and minimal TTL algorithms are not precise algorithms but approximated# algorithms (in order to save memory), so you can tune it for speed or# accuracy. For default Redis will check five keys and pick the one that was# used less recently, you can change the sample size using the following# configuration directive.## The default of 5 produces good enough results. 10 Approximates very closely# true LRU but costs a bit more CPU. 3 is very fast but not very accurate.## maxmemory-samples 5
############################## APPEND ONLY MODE ###############################
# By default Redis asynchronously dumps the dataset on disk. This mode is# good enough in many applications, but an issue with the Redis process or# a power outage may result into a few minutes of writes lost (depending on# the configured save points).## The Append Only File is an alternative persistence mode that provides# much better durability. For instance using the default data fsync policy# (see later in the config file) Redis can lose just one second of writes in a# dramatic event like a server power outage, or a single write if something# wrong with the Redis process itself happens, but the operating system is# still running correctly.## AOF and RDB persistence can be enabled at the same time without problems.# If the AOF is enabled on startup Redis will load the AOF, that is the file# with the better durability guarantees.## Please check http://redis.io/topics/persistence for more information.
# redis 默认每次更新操作后会在后台异步的把数据库镜像备份到磁盘,但该备份非常耗时,且备份不宜太频繁# redis 同步数据文件是按上面save条件来同步的# 如果发生诸如拉闸限电、拔插头等状况,那么将造成比较大范围的数据丢失# 所以redis提供了另外一种更加高效的数据库备份及灾难恢复方式# 开启append only 模式后,redis 将每一次写操作请求都追加到appendonly.aof 文件中# redis重新启动时,会从该文件恢复出之前的状态。# 但可能会造成 appendonly.aof 文件过大,所以redis支持BGREWRITEAOF 指令,对appendonly.aof重新整理,默认是不开启的。
appendonly no
# The name of the append only file (default: "appendonly.aof")# 默认为appendonly.aof。appendfilename "appendonly.aof"
# The fsync() call tells the Operating System to actually write data on disk# instead of waiting for more data in the output buffer. Some OS will really flush# data on disk, some other OS will just try to do it ASAP.## Redis supports three different modes:## no: don't fsync, just let the OS flush the data when it wants. Faster.# always: fsync after every write to the append only log. Slow, Safest.# everysec: fsync only one time every second. Compromise.## The default is "everysec", as that's usually the right compromise between# speed and data safety. It's up to you to understand if you can relax this to# "no" that will let the operating system flush the output buffer when# it wants, for better performances (but if you can live with the idea of# some data loss consider the default persistence mode that's snapshotting),# or on the contrary, use "always" that's very slow but a bit safer than# everysec.## More details please check the following article:# http://antirez.com/post/redis-persistence-demystified.html## If unsure, use "everysec".
# 设置对 appendonly.aof 文件进行同步的频率,有三种选择always、everysec、no,默认是everysec表示每秒同步一次。# always 表示每次有写操作都进行同步,everysec 表示对写操作进行累积,每秒同步一次。# no表示等操作系统进行数据缓存同步到磁盘,都进行同步,everysec 表示对写操作进行累积,每秒同步一次# appendfsync always# appendfsync everysec# appendfsync no
# When the AOF fsync policy is set to always or everysec, and a background# saving process (a background save or AOF log background rewriting) is# performing a lot of I/O against the disk, in some Linux configurations# Redis may block too long on the fsync() call. Note that there is no fix for# this currently, as even performing fsync in a different thread will block# our synchronous write(2) call.## In order to mitigate this problem it's possible to use the following option# that will prevent fsync() from being called in the main process while a# BGSAVE or BGREWRITEAOF is in progress.## This means that while another child is saving, the durability of Redis is# the same as "appendfsync none". In practical terms, this means that it is# possible to lose up to 30 seconds of log in the worst scenario (with the# default Linux settings).## If you have latency problems turn this to "yes". Otherwise leave it as# "no" that is the safest pick from the point of view of durability.# 指定是否在后台aof文件rewrite期间调用fsync,默认为no,表示要调用fsync(无论后台是否有子进程在刷盘)。Redis在后台写RDB文件或重写afo文件期间会存在大量磁盘IO,此时,在某些linux系统中,调用fsync可能会阻塞。no-appendfsync-on-rewrite yes
# Automatic rewrite of the append only file.# Redis is able to automatically rewrite the log file implicitly calling# BGREWRITEAOF when the AOF log size grows by the specified percentage.## This is how it works: Redis remembers the size of the AOF file after the# latest rewrite (if no rewrite has happened since the restart, the size of# the AOF at startup is used).## This base size is compared to the current size. If the current size is# bigger than the specified percentage, the rewrite is triggered. Also# you need to specify a minimal size for the AOF file to be rewritten, this# is useful to avoid rewriting the AOF file even if the percentage increase# is reached but it is still pretty small.## Specify a percentage of zero in order to disable the automatic AOF# rewrite feature.# 指定Redis重写aof文件的条件,默认为100,表示与上次rewrite的aof文件大小相比,当前aof文件增长量超过上次afo文件大小的100%时,就会触发background rewrite。若配置为0,则会禁用自动rewriteauto-aof-rewrite-percentage 100
# 指定触发rewrite的aof文件大小。若aof文件小于该值,即使当前文件的增量比例达到auto-aof-rewrite-percentage的配置值,也不会触发自动rewrite。即这两个配置项同时满足时,才会触发rewrite。auto-aof-rewrite-min-size 64mb
# An AOF file may be found to be truncated at the end during the Redis# startup process, when the AOF data gets loaded back into memory.# This may happen when the system where Redis is running# crashes, especially when an ext4 filesystem is mounted without the# data=ordered option (however this can't happen when Redis itself# crashes or aborts but the operating system still works correctly).## Redis can either exit with an error when this happens, or load as much# data as possible (the default now) and start if the AOF file is found# to be truncated at the end. The following option controls this behavior.## If aof-load-truncated is set to yes, a truncated AOF file is loaded and# the Redis server starts emitting a log to inform the user of the event.# Otherwise if the option is set to no, the server aborts with an error# and refuses to start. When the option is set to no, the user requires# to fix the AOF file using the "redis-check-aof" utility before to restart# the server.## Note that if the AOF file will be found to be corrupted in the middle# the server will still exit with an error. This option only applies when# Redis will try to read more data from the AOF file but not enough bytes# will be found.aof-load-truncated yes
################################ LUA SCRIPTING  ###############################
# Max execution time of a Lua script in milliseconds.## If the maximum execution time is reached Redis will log that a script is# still in execution after the maximum allowed time and will start to# reply to queries with an error.## When a long running script exceeds the maximum execution time only the# SCRIPT KILL and SHUTDOWN NOSAVE commands are available. The first can be# used to stop a script that did not yet called write commands. The second# is the only way to shut down the server in the case a write command was# already issued by the script but the user doesn't want to wait for the natural# termination of the script.## Set it to 0 or a negative value for unlimited execution without warnings.# 一个Lua脚本最长的执行时间,单位为毫秒,如果为0或负数表示无限执行时间,默认为5000lua-time-limit 5000
################################ REDIS CLUSTER  ################################# ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++# WARNING EXPERIMENTAL: Redis Cluster is considered to be stable code, however# in order to mark it as "mature" we need to wait for a non trivial percentage# of users to deploy it in production.# ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++## Normal Redis instances can't be part of a Redis Cluster; only nodes that are# started as cluster nodes can. In order to start a Redis instance as a# cluster node enable the cluster support uncommenting the following:## cluster-enabled yes
# Every cluster node has a cluster configuration file. This file is not# intended to be edited by hand. It is created and updated by Redis nodes.# Every Redis Cluster node requires a different cluster configuration file.# Make sure that instances running in the same system do not have# overlapping cluster configuration file names.## cluster-config-file nodes-6379.conf
# Cluster node timeout is the amount of milliseconds a node must be unreachable# for it to be considered in failure state.# Most other internal time limits are multiple of the node timeout.## cluster-node-timeout 15000
# A slave of a failing master will avoid to start a failover if its data# looks too old.## There is no simple way for a slave to actually have a exact measure of# its "data age", so the following two checks are performed:## 1) If there are multiple slaves able to failover, they exchange messages#    in order to try to give an advantage to the slave with the best#    replication offset (more data from the master processed).#    Slaves will try to get their rank by offset, and apply to the start#    of the failover a delay proportional to their rank.## 2) Every single slave computes the time of the last interaction with#    its master. This can be the last ping or command received (if the master#    is still in the "connected" state), or the time that elapsed since the#    disconnection with the master (if the replication link is currently down).#    If the last interaction is too old, the slave will not try to failover#    at all.## The point "2" can be tuned by user. Specifically a slave will not perform# the failover if, since the last interaction with the master, the time# elapsed is greater than:##   (node-timeout * slave-validity-factor) + repl-ping-slave-period## So for example if node-timeout is 30 seconds, and the slave-validity-factor# is 10, and assuming a default repl-ping-slave-period of 10 seconds, the# slave will not try to failover if it was not able to talk with the master# for longer than 310 seconds.## A large slave-validity-factor may allow slaves with too old data to failover# a master, while a too small value may prevent the cluster from being able to# elect a slave at all.## For maximum availability, it is possible to set the slave-validity-factor# to a value of 0, which means, that slaves will always try to failover the# master regardless of the last time they interacted with the master.# (However they'll always try to apply a delay proportional to their# offset rank).## Zero is the only value able to guarantee that when all the partitions heal# the cluster will always be able to continue.## cluster-slave-validity-factor 10
# Cluster slaves are able to migrate to orphaned masters, that are masters# that are left without working slaves. This improves the cluster ability# to resist to failures as otherwise an orphaned master can't be failed over# in case of failure if it has no working slaves.## Slaves migrate to orphaned masters only if there are still at least a# given number of other working slaves for their old master. This number# is the "migration barrier". A migration barrier of 1 means that a slave# will migrate only if there is at least 1 other working slave for its master# and so forth. It usually reflects the number of slaves you want for every# master in your cluster.## Default is 1 (slaves migrate only if their masters remain with at least# one slave). To disable migration just set it to a very large value.# A value of 0 can be set but is useful only for debugging and dangerous# in production.## cluster-migration-barrier 1
# By default Redis Cluster nodes stop accepting queries if they detect there# is at least an hash slot uncovered (no available node is serving it).# This way if the cluster is partially down (for example a range of hash slots# are no longer covered) all the cluster becomes, eventually, unavailable.# It automatically returns available as soon as all the slots are covered again.## However sometimes you want the subset of the cluster which is working,# to continue to accept queries for the part of the key space that is still# covered. In order to do so, just set the cluster-require-full-coverage# option to no.## cluster-require-full-coverage yes
# In order to setup your cluster make sure to read the documentation# available at http://redis.io web site.
################################## SLOW LOG ###################################
# The Redis Slow Log is a system to log queries that exceeded a specified# execution time. The execution time does not include the I/O operations# like talking with the client, sending the reply and so forth,# but just the time needed to actually execute the command (this is the only# stage of command execution where the thread is blocked and can not serve# other requests in the meantime).## You can configure the slow log with two parameters: one tells Redis# what is the execution time, in microseconds, to exceed in order for the# command to get logged, and the other parameter is the length of the# slow log. When a new command is logged the oldest one is removed from the# queue of logged commands.
# The following time is expressed in microseconds, so 1000000 is equivalent# to one second. Note that a negative number disables the slow log, while# a value of zero forces the logging of every command.slowlog-log-slower-than 10000
# There is no limit to this length. Just be aware that it will consume memory.# You can reclaim memory used by the slow log with SLOWLOG RESET.slowlog-max-len 128
################################ LATENCY MONITOR ##############################
# The Redis latency monitoring subsystem samples different operations# at runtime in order to collect data related to possible sources of# latency of a Redis instance.## Via the LATENCY command this information is available to the user that can# print graphs and obtain reports.## The system only logs operations that were performed in a time equal or# greater than the amount of milliseconds specified via the# latency-monitor-threshold configuration directive. When its value is set# to zero, the latency monitor is turned off.## By default latency monitoring is disabled since it is mostly not needed# if you don't have latency issues, and collecting data has a performance# impact, that while very small, can be measured under big load. Latency# monitoring can easily be enabled at runtime using the command# "CONFIG SET latency-monitor-threshold <milliseconds>" if needed.latency-monitor-threshold 0
############################# EVENT NOTIFICATION ##############################
# Redis can notify Pub/Sub clients about events happening in the key space.# This feature is documented at http://redis.io/topics/notifications## For instance if keyspace events notification is enabled, and a client# performs a DEL operation on key "foo" stored in the Database 0, two# messages will be published via Pub/Sub:## PUBLISH [email protected]__:foo del# PUBLISH [email protected]__:del foo## It is possible to select the events that Redis will notify among a set# of classes. Every class is identified by a single character:##  K     Keyspace events, published with [email protected]<db>__ prefix.#  E     Keyevent events, published with [email protected]<db>__ prefix.#  g     Generic commands (non-type specific) like DEL, EXPIRE, RENAME, ...#  $     String commands#  l     List commands#  s     Set commands#  h     Hash commands#  z     Sorted set commands#  x     Expired events (events generated every time a key expires)#  e     Evicted events (events generated when a key is evicted for maxmemory)#  A     Alias for g$lshzxe, so that the "AKE" string means all the events.##  The "notify-keyspace-events" takes as argument a string that is composed#  of zero or multiple characters. The empty string means that notifications#  are disabled.##  Example: to enable list and generic events, from the point of view of the#           event name, use:##  notify-keyspace-events Elg##  Example 2: to get the stream of the expired keys subscribing to channel#             name [email protected]__:expired use:##  notify-keyspace-events Ex##  By default all notifications are disabled because most users don't need#  this feature and the feature has some overhead. Note that if you don't#  specify at least one of K or E, no events will be delivered.notify-keyspace-events ""
############################### ADVANCED CONFIG ###############################
# Hashes are encoded using a memory efficient data structure when they have a# small number of entries, and the biggest entry does not exceed a given# threshold. These thresholds can be configured using the following directives.# 当hash中包含超过指定元素个数并且最大的元素没有超过临界时,# hash将以一种特殊的编码方式(大大减少内存使用)来存储,这里可以设置这两个临界值hash-max-ziplist-entries 512hash-max-ziplist-value 64
# Similarly to hashes, small lists are also encoded in a special way in order# to save a lot of space. The special representation is only used when# you are under the following limits:# list数据类型多少节点以下会采用去指针的紧凑存储格式。# list数据类型节点值大小小于多少字节会采用紧凑存储格式。list-max-ziplist-entries 512list-max-ziplist-value 64
# Sets have a special encoding in just one case: when a set is composed# of just strings that happen to be integers in radix 10 in the range# of 64 bit signed integers.# The following configuration setting sets the limit in the size of the# set in order to use this special memory saving encoding.# set数据类型内部数据如果全部是数值型,且包含多少节点以下会采用紧凑格式存储。set-max-intset-entries 512
# Similarly to hashes and lists, sorted sets are also specially encoded in# order to save a lot of space. This encoding is only used when the length and# elements of a sorted set are below the following limits:
# zsort数据类型多少节点以下会采用去指针的紧凑存储格式。# zsort数据类型节点值大小小于多少字节会采用紧凑存储格式。zset-max-ziplist-entries 128zset-max-ziplist-value 64
# HyperLogLog sparse representation bytes limit. The limit includes the# 16 bytes header. When an HyperLogLog using the sparse representation crosses# this limit, it is converted into the dense representation.## A value greater than 16000 is totally useless, since at that point the# dense representation is more memory efficient.## The suggested value is ~ 3000 in order to have the benefits of# the space efficient encoding without slowing down too much PFADD,# which is O(N) with the sparse encoding. The value can be raised to# ~ 10000 when CPU is not a concern, but space is, and the data set is# composed of many HyperLogLogs with cardinality in the 0 - 15000 range.hll-sparse-max-bytes 3000
# Active rehashing uses 1 millisecond every 100 milliseconds of CPU time in# order to help rehashing the main Redis hash table (the one mapping top-level# keys to values). The hash table implementation Redis uses (see dict.c)# performs a lazy rehashing: the more operation you run into a hash table# that is rehashing, the more rehashing "steps" are performed, so if the# server is idle the rehashing is never complete and some more memory is used# by the hash table.## The default is to use this millisecond 10 times every second in order to# actively rehash the main dictionaries, freeing memory when possible.## If unsure:# use "activerehashing no" if you have hard latency requirements and it is# not a good thing in your environment that Redis can reply from time to time# to queries with 2 milliseconds delay.## use "activerehashing yes" if you don't have such hard requirements but# want to free memory asap when possible.
# Redis将在每100毫秒时使用1毫秒的CPU时间来对redis的hash表进行重新hash,可以降低内存的使用# 当你的使用场景中,有非常严格的实时性需要,不能够接受Redis时不时的对请求有2毫秒的延迟的话,把这项配置为no。# 如果没有这么严格的实时性要求,可以设置为yes,以便能够尽可能快的释放内存activerehashing yes
# The client output buffer limits can be used to force disconnection of clients# that are not reading data from the server fast enough for some reason (a# common reason is that a Pub/Sub client can't consume messages as fast as the# publisher can produce them).## The limit can be set differently for the three different classes of clients:## normal -> normal clients including MONITOR clients# slave  -> slave clients# pubsub -> clients subscribed to at least one pubsub channel or pattern## The syntax of every client-output-buffer-limit directive is the following:## client-output-buffer-limit <class> <hard limit> <soft limit> <soft seconds>## A client is immediately disconnected once the hard limit is reached, or if# the soft limit is reached and remains reached for the specified number of# seconds (continuously).# So for instance if the hard limit is 32 megabytes and the soft limit is# 16 megabytes / 10 seconds, the client will get disconnected immediately# if the size of the output buffers reach 32 megabytes, but will also get# disconnected if the client reaches 16 megabytes and continuously overcomes# the limit for 10 seconds.## By default normal clients are not limited because they don't receive data# without asking (in a push way), but just after a request, so only# asynchronous clients may create a scenario where data is requested faster# than it can read.## Instead there is a default limit for pubsub and slave clients, since# subscribers and slaves receive data in a push fashion.## Both the hard or the soft limit can be disabled by setting them to zero.client-output-buffer-limit normal 0 0 0client-output-buffer-limit slave 256mb 64mb 60client-output-buffer-limit pubsub 32mb 8mb 60
# Redis calls an internal function to perform many background tasks, like# closing connections of clients in timeout, purging expired keys that are# never requested, and so forth.## Not all tasks are performed with the same frequency, but Redis checks for# tasks to perform according to the specified "hz" value.## By default "hz" is set to 10. Raising the value will use more CPU when# Redis is idle, but at the same time will make Redis more responsive when# there are many keys expiring at the same time, and timeouts may be# handled with more precision.## The range is between 1 and 500, however a value over 100 is usually not# a good idea. Most users should use the default of 10 and raise this up to# 100 only in environments where very low latency is required.hz 10
# When a child rewrites the AOF file, if the following option is enabled# the file will be fsync-ed every 32 MB of data generated. This is useful# in order to commit the file to the disk more incrementally and avoid# big latency spikes.# aof rewrite过程中,是否采取增量文件同步策略,默认为“yes”。 rewrite过程中,每32M数据进行一次文件同步,这样可以减少aof大文件写入对磁盘的操作次数aof-rewrite-incremental-fsync yes

# redis数据存储redis的存储分为内存存储、磁盘存储和log文件三部分,配置文件中有三个参数对其进行配置。save seconds updates,save配置,指出在多长时间内,有多少次更新操作,就将数据同步到数据文件。可多个条件配合,默认配置了三个条件。appendonly yes/no ,appendonly配置,指出是否在每次更新操作后进行日志记录,如果不开启,可能会在断电时导致一段时间内的数据丢失。因为redis本身同步数据文件是按上面的save条件来同步的,所以有的数据会在一段时间内只存在于内存中。appendfsync no/always/everysec ,appendfsync配置,no表示等操作系统进行数据缓存同步到磁盘,always表示每次更新操作后手动调用fsync()将数据写到磁盘,everysec表示每秒同步一次。

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