Redis from persistent storage with the master copy

4. redis persistence

RedisIt is a memory database, once the server process exits, the data in the database will be lost, in order to solve this problem, Redisprovides two of a lasting solution to save the data in memory to disk, to avoid loss of data.

4.1 RDB persistence

redisProvides RDB持久化functionality, this feature can redissave the state in memory to the hard disk, it can perform a manual.

Can also be re- redis.confconfigured, regularly perform .

RDB RDB persistence produced a file is compressed in a binary file , the file is saved on the hard disk, redis can restore the state of the database at the time of the adoption of the document.

Advantages: speed, suitable for backup, Master-slave replication is based on the RDB persistence function

配置参数:
touch  redis-rdb.conf  
加入如下的内容
daemonize yes                    #后台运行redis
port 6379                        #指定redis的端口 
logfile /data/6379/redis.log     #redis日志文件    
dir /data/6379/                  #定义持久化文件存储位置，需要手动创建文件夹
dbfilename  redis-rdb.rdb        #rdb持久化文件
bind 0.0.0.0                     #redis启动地址
save 10  5                #10秒内，超过5个修改类的操作，就触发持久化

Manual trigger

127.0.0.1:6379> save
OK

4.2 AOF persistence

AOF (append-only log file)
record of all operation commands executed by the server (e.g., set del, etc.), and when the server starts, be reduced by re-executing the command data sets
AOF commands in the file save all format redis protocol the new command is appended to the end of the file.
Advantages: maximum program to ensure that data is not lost
drawback: very large logging

redis-client   写入数据  >  redis-server   同步命令   >  AOF文件

Configuration parameters

AOF持久化配置，两条参数

appendonly   yes
appendfsync  always     总是修改类的操作
             everysec   每秒做一次持久化
             no     依赖于系统自带的缓存大小机制

touch redis-aof.conf

daemonize yes
port 6379
logfile /data/6379/redis.log
dir /data/6379
appendonly yes
appendfsync everysec

Start redis service

redis-server /etc/redis.conf

Check the redis data directory / data / 6379 / aof whether or not a file

[root@linux 6379]# ls
appendonly.aof  dbmp.rdb  redis.log

[root@linux 6379]# tail -f appendonly.aof

Set up a new key, check aof information, and then close redis, check whether the data persistence

pkill -9 redis

redis-server /etc/redis.conf

redis-cli

4.3 does not restart to switch data aof rdb

Step 1: Prepare a rdb database of redis

Step Two: In redis database, aof activation mode, off mode rdb, the following command

127.0.0.1:6379> CONFIG set appendonly yes 
OK
127.0.0.1:6379> CONFIG SET save ""
OK

Modify the command rdb and aof the persistence mechanism, to take effect is only temporary, permanent need to modify the configuration file

5. redis master copy from

principle:

SYNC command sent from the server to the master server.
Received the SYNC command master server calls BGSAVE command to create a RDB file, and use all the write command buffer recording executed next.
When the primary server BGSAVE been executed command, it sends to the server RDB
And will receive and load the file from the server.
All the write command buffer primary server will store sent from the server to execute.

1, when the opening from the master copy, using the RDB data synchronization from the master
2 after the synchronization start propagate through the master database command, copy active manner,
mechanisms to achieve PSYNC after 3,2.8 achieve break Reconnection

5.1 Environment Preparation

Preparation 3 redis profile

6380.conf

mkdir /data/638{0..2}  # 创建6380 6381 6382文件夹

6380.conf
vim   /data/6380/redis.conf
port 6380
daemonize yes
pidfile /data/6380/redis.pid
loglevel notice
logfile "/data/6380/redis.log"
dbfilename dump.rdb
dir /data/6380
protected-mode no

6381.conf

vim   /data/6381/redis.conf
port 6381
daemonize yes
pidfile /data/6381/redis.pid
loglevel notice
logfile "/data/6381/redis.log"
dbfilename dump.rdb
dir /data/6381
protected-mode no

6382.conf

port 6382
daemonize yes
pidfile /data/6382/redis.pid
loglevel notice
logfile "/data/6382/redis.log"
dbfilename dump.rdb
dir /data/6382
protected-mode no

Start three instances redis

redis-server /data/6380/redis.conf
redis-server /data/6381/redis.conf
redis-server /data/6382/redis.conf

From the main planning

主节点：6380
从节点：6381、6382

5.2 Configuration master-slave synchronization

6381/6382 Command Line

redis-cli -p 6381
    SLAVEOF 127.0.0.1 6380  #指明主库的地址

redis-cli -p 6382
    SLAVEOF 127.0.0.1 6380  #指明主库的地址

Check the status of master

From the library:

127.0.0.1:6382> info replication
127.0.0.1:6381> info replication

Main Library:

127.0.0.1:6380> info replication

5.3 switching from manual master copy failure

# 关闭主库6380redis-cli -p 6380
shutdown

Check the information from the master database, this time master_link_status: down

redis-cli -p 6381
info replication
redis-cli -p 6382
info replication

1. Turn off the 6381 identity from the library

redis-cli -p 6381
info replication
slaveof no one

2. The library from 6382 to 6381

6382连接到6381：
[root@linux ~]# redis-cli -p 6382
127.0.0.1:6382> SLAVEOF no one
127.0.0.1:6382> SLAVEOF 127.0.0.1 6381

3. Check the main information from 6382,6381