Redis Cluster：Redis Cluster提供了一种真正的实时的高可用解决方案，在Redis Cluster集群中，任意一个节点的宕机均不会对服务产生影响，slave角色的节点可以无缝接替宕机的master节点对外继续提供服务。
例如，在一个三主三从的Redis Cluster中，Redis Cluster供定义了16384(0~16383)个slots（槽），并将这些slots均匀分布Redis Cluster的三个主节点中，如0~5000个slots属于主节点A，5001~10000个slots属于主节点B，10001~16383个slot属于主节点C，Redis中任意一个key经过CRC16校验后的校验值始终在0~16383范围中，Redis Cluster根据该key的校验值将该Key存入和该slot值一致的节点上，A1、B1、C1分别为A、B、C的从节点，自动从对应的主节点同步slots信息和slots中的key数据，当主节点宕机后，从节点立刻执行故障转义变成主节点继续提供服务。
一个三主三从的Redis Cluster如下所示
我们以三主三从的架构进行Redis Cluster环境部署
| 主机名 | IP地址 | 角色 | 安装目录 | 版本 |
| redis-master-01 | 172.16.101.54 | Master | /usr/local/redis | Version 3.12 |
| redis-master-02 | 172.16.101.55 | Master | ||
| redis-master-03 | 172.16.101.56 | Master | ||
| redis-slave-01 | 172.16.101.58 | Slave | ||
| redis-slave-02 | 172.16.101.59 | Slave | ||
| redis-slave-03 | 172.16.101.60 | Slave |
一.各节点系统环境配置
新建运行redis的用户和组
# groupadd -r dba # useradd -r -g dba -G root redis # cat /home/redis/.bash_profile ................ PATH=/usr/local/redis/src:$PATH:$HOME/.local/bin:$HOME/bin ................
系统内核参数优化
# cat /etc/sysctl.conf ....................... vm.overcommit_memory=1 vm.swappiness=1 fs.aio-max-nr=1048576 fs.file-max= 7672460 net.ipv4.ip_local_port_range=9000 65500 net.core.rmem_default=262144 net.core.rmem_max=4194304 net.core.wmem_default=262144 net.core.wmem_max=1048586 net.core.somaxconn = 2048 kernel.sem= 50100 64128000 50100 1280 kernel.shmall=5242880 kernel.shmmax=12884901888 .......................
redis运行资源优化
# cat /etc/security/limits.conf .................................. redis soft nproc 65536 redis hard nproc 65536 redis soft nofile 65536 redis hard nofile 65536 ..................................
大页面文件优化
# echo "echo never > /sys/kernel/mm/transparent_hugepage/enabled" >> /etc/rc.local
二.各节点redis安装
# mkdir /usr/local/redis # chown -R redis.dba /usr/local/redis $ cd /usr/local/redis $ tar -zxf redis-3.2.12.tar.gz $ mv redis-3.2.12/* . $ rm -rf redis-3.2.12* $ make $ mkdir {data,log,conf} $ mv redis.conf conf
三. 配置各节点redis配置文件，如下所示，这里仅列出主要参数
bind 0.0.0.0 protected-mode no port 6379 tcp-backlog 1024 timeout 0 tcp-keepalive 0 daemonize yes supervised systemd pidfile /var/run/redis_6379.pid loglevel notice logfile "/usr/local/redis/log/redis.log" dir "/usr/local/redis/data" slave-read-only yes repl-ping-slave-period 3 repl-timeout 15 slave-priority 100 min-slaves-to-write 1 min-slaves-max-lag 10 rename-command flushall "" rename-command flushdb "" rename-command save "" rename-command keys "" maxclients 10000 maxmemory 4gb maxmemory-policy allkeys-lru appendonly yes appendfilename "appendonly.aof" appendfsync everysec cluster-enabled yes cluster-config-file nodes.conf cluster-node-timeout 5000 cluster-slave-validity-factor 10 cluster-migration-barrier 1 cluster-require-full-coverage yes
四.将redis配置为系统服务
# cat /usr/lib/systemd/system/redis.service [Unit] Description=Redis In-Memory Data Store Documentation=https://redis.io/documentation After=syslog.target After=network.target [Service] Type=notify User=redis Group=dba Restart=always # Disable OOM kill on the Redis OOMScoreAdjust=-1000 Environment=PG_OOM_ADJUST_FILE=/proc/self/oom_score_adj Environment=PG_OOM_ADJUST_VALUE=0 ExecStart=/usr/local/redis/src/redis-server /usr/local/redis/conf/redis.conf ExecStop=/bin/kill -15 $MAINPID LimitNOFILE=65536 [Install] WantedBy=multi-user.target
# systemctl daemon-reload
# systemctl enable redis
# systemctl start redis
# systemctl status redis
各节点启动成功后，会自动生成一个唯一的node-id,且在默认开启集群功能后，各节点均认为自己是主节点，从log中我们可以看出
172.16.101.54
25630:M 12 Apr 00:59:59.477 * No cluster configuration found, I'm 89a83af689b194b18c7f5c0dae105c329a6a831f
172.16.101.55
6232:M 12 Apr 00:59:59.450 * No cluster configuration found, I'm 6c9558d05f3d5a1b2dac4ebe31d581b1581f6112
172.16.101.56
28099:M 12 Apr 00:59:59.478 * No cluster configuration found, I'm 684908fde2ccc85fa2caf2fbbbfaa0e9f470cf04
172.16.101.58
25490:M 12 Apr 01:01:07.832 * No cluster configuration found, I'm 310edd63d50d3d1412e6413b9c4d2ff31e2fae5f
172.16.101.59
27836:M 12 Apr 01:01:07.835 * No cluster configuration found, I'm 63eef92da475574c62485543ac57898d13618520
172.16.101.60
15314:M 12 Apr 01:01:07.839 * No cluster configuration found, I'm c7095b2f9adf4adada4fb0afd953ab7439ccc058
查看当前集群节点信息
redis-master-01:6379> info cluster # Cluster cluster_enabled:1 redis-master-01:6379> cluster info cluster_state:fail cluster_slots_assigned:0 cluster_slots_ok:0 cluster_slots_pfail:0 cluster_slots_fail:0 cluster_known_nodes:1 cluster_size:0 cluster_current_epoch:0 cluster_my_epoch:0 cluster_stats_messages_sent:0 cluster_stats_messages_received:0 redis-master-01:6379> cluster nodes 89a83af689b194b18c7f5c0dae105c329a6a831f :6379 myself,master - 0 0 0 connected
通过以上可以看出
- 当前集群功能已经开启，cluster_enabled:1
- 集群功能fail状态，cluster_state:fail
- 集群未分配任何slots，cluster_slots_assigned:0
- 集群中只能查看自身节点的简单信息，cluster_known_nodes:1、 89a83af689b194b18c7f5c0dae105c329a6a831f :6379 myself,master - 0 0 0 connected