3个月前 (08-22)  Redis |   抢沙发  28 
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布署方案说明

1、sentinel负责对redis集群中的主从服务监控、提醒和自动故障转移

2、redis集群负责对外提供相关服务

Sentinel原理介绍

原理:sentinel是一个分布式系统,可以在一个架构中运行多个sentinel进程,这些进程使用流言协议(gossip protocols)来接收关于rdis主服务器是否下线的信息,并使用投票协议(agreement protocols)来决定是否执行自动故障迁移,以及选举哪个从服务器成为新的主服务器。

流言协议:sentinel服务通过ping命令来确认监控的服务器是否正常,当足够多数量的sentinel都确认监控的同一服务器停止服务了(主观下线),则判定此服务器停止服务。

投票协议:其实就选举,sentinel集群根据一定的规则从redis群中选择一个新的服务器成为主服务器,并使其它的服务器做为新的从服务器,并修改自身的配置文件。

服务器布署规划

实验环境采用两台服务器模拟集群环境

服务器系统环境

Centos 6.6 x86_64

Master服务器  10.0.0.3/24

Redis-Mster 10.0.0.3:6379

Redis-Slave1 10.0.0.3:63791

Redis-Slave2 10.0.0.3:63792

Sentinel服务

s 10.0.0.3:26379

s1 10.0.0.3:26378

Slave服务器  10.0.0.4/24

Redis-Slave3 10.0.0.4:63793

Redis-Slave4 10.0.0.4:63794

Sentinel服务

s2 10.0.0.4:26379

s3 10.0.0.4:26378

故障切换前后逻辑图

Redis集群生产环境高可用方案实战过程

Redis集群生产环境高可用方案实战过程

Redis-sentinel服务配置

主服务器上安装布署过程

安装redis服务

mkdir /usr/local/redis/data
cd /usr/local/src
wget http://download.redis.io/releases/redis-2.8.9.tar.gz
tar zxf redis-2.8.9.tar.gz
cd redis-2.8.9
make && make install

复制配置文件

cp redis.conf /usr/local/bin/
cd /usr/local/bin
cp redis.conf redis-slave1
cp redis.conf redis-slave2

修改配置文件

[root@master bin]#vi redis.conf
    daemonize yes        
         #开启后台运行模式
    pidfile /var/run/redis.pid
    bind 10.0.0.3
    dbfilename dump.rdb
    dir /usr/local/redis/data
    port 6379
[root@master bin]#vi redis-slave1
    daemonize yes
    pidfile /var/run/redis-slave1.pid
    port 63791
    bind 10.0.0.3
    dbfilename dump-slave1.rdb
    dir /usr/local/redis/data
    slaveof 10.0.0.3 6379
    slave-read-only yes
[root@master bin]#vi redis-slave2
    daemonize yes
    pidfile /var/run/redis-slave2.pid
    port 63792
    bind 10.0.0.3
    dbfilename dump-slave2.rdb
    dir /usr/local/redis/data
    slaveof 10.0.0.3 6379

配置redis-sentinel服务

mkdir /var/log/redis -p
cp /usr/local/src/redis-2.8.9/src/redis-sentinel /usr/bin/
cp /usr/local/src/redis-2.8.9/src/sentinel.conf /usr/local/bin/
cd /usr/local/bin
cp sentinel.conf sentinel-s1.conf

修改配置文件

[root@master bin]# egrep -v "^#|^$" sentinel.conf
    port 26379
    daemonize yes
    logfile /var/log/redis/sentinel.log
    sentinel monitor mymaster 10.0.0.3 6379 2
    sentinel down-after-milliseconds mymaster 30000
    sentinel parallel-syncs mymaster 1
    sentinel failover-timeout mymaster 180000
[root@master bin]# egrep -v "^#|^$" sentinel-s1.conf
    port 26378
    daemonize yes
    logfile /var/log/redis/sentinel-s1.log
    sentinel monitor mymaster 10.0.0.3 6379 2
    sentinel down-after-milliseconds mymaster 30000
    sentinel parallel-syncs mymaster 1
    sentinel failover-timeout mymaster 180000

以上配置从服务器操作过程同上

启动服务

启动redis服务

[root@master bin]# redis-server redis.conf
[root@master bin]# redis-server redis-slave1
[root@master bin]# redis-server redis-slave2
[root@master bin]# ps -ef|grep redis       
    root    2579    1  0 23:55 ?  00:00:00 redis-server 10.0.0.3:6379
    root    2585    1  0 23:55 ?  00:00:00 redis-server 10.0.0.3:63792
    root   2590    1  0 23:55 ?   00:00:00 redis-server 10.0.0.3:63791
    root  2597  2479 0 23:56 pts/0  00:00:00 grep --color=auto redis
[root@slave bin]# redis-server redis-slave3
[root@slave bin]# redis-server redis-slave4
[root@slave bin]#  ps -ef|grep redis
    root  2576 1  0 23:56 ?  00:00:00 redis-server 10.0.0.4:63793
    root  2580  1  0 23:56 ?  00:00:00 redis-server 10.0.0.4:63794
    root 2584 2502 0 23:56 00:00:00 grep --color=auto redis

启动redis-sentinel服务

[root@master bin]# redis-sentinel sentinel.conf
[root@master bin]# redis-sentinel sentinel-s1.conf
[root@master bin]# ps -ef|grep redis-sentinel            
    root  2638  1  0 01:05 ?   00:00:04 redis-sentinel *:26379
    root  2646 1  0 01:13 ?   00:00:00 redis-sentinel *:26378
    root  2650 2479 0 01:13 00:00:00 grep --color=auto redis
[root@slave bin]# redis-sentinel sentinel-s2.conf
[root@slave bin]# redis-sentinel sentinel-s3.conf 
[root@slave bin]# ps -ef|grep redis-sentinel
    root 2644    1  1 01:14 ?   00:00:00 redis-sentinel *:26378
    root  2649   1  0 01:14 ?   00:00:00 redis-sentinel *:26379
    root  2653   2502  0 01:15 00:00:00 grep --color=auto redis-sentinel

查看日志观察启动过程

[root@master bin]# tail -f /var/log/redis/sentinel.log
              `-.__.-'                                               
    [2664] 12 May 01:20:11.036 # Sentinel runid is c327be464ef36e670566a0d76c9dc85bac7f33b1
    [2664] 12 May 01:20:11.036 # +monitor master mymaster 10.0.0.3 6379 quorum 2
    [2664] 12 May 01:20:11.123 * -dup-sentinel master mymaster 10.0.0.3 6379 #duplicate of 10.0.0.3:26378 or fb1fbe73b51a0a6e71a8ceae57d34ef773d086e3
    [2664] 12 May 01:20:11.123 * +sentinel sentinel 10.0.0.3:26378 10.0.0.3 26378 @ mymaster 10.0.0.3 6379
    [2664] 12 May 01:20:21.410 * -dup-sentinel master mymaster 10.0.0.3 6379 #duplicate of 10.0.0.4:26379 or 3d43ddea4d4ba8de7dd30e2d332723508f6d4c19
    [2664] 12 May 01:20:21.410 * +sentinel sentinel 10.0.0.4:26379 10.0.0.4 26379 @ mymaster 10.0.0.3 6379
    [2664] 12 May 01:20:25.103 * -dup-sentinel master mymaster 10.0.0.3 6379 #duplicate of 10.0.0.4:26378 or 6d134d9a3e53c0cb70de842281de8aaf17a84c00
    [2664] 12 May 01:20:25.103 * +sentinel sentinel 10.0.0.4:26378 10.0.0.4 26378 @ mymaster 10.0.0.3 6379

可以看出有其它监控服务器加入到集群中来

查看配置文件是否有变化

[root@master bin]# egrep -v "^#|^$" sentinel-s1.conf                
    port 26378
    daemonize yes
    logfile "/var/log/redis/sentinel-s1.log"
    sentinel monitor mymaster 10.0.0.3 6379 2
    sentinel config-epoch mymaster 0
    sentinel leader-epoch mymaster 0
    sentinel known-slave mymaster 10.0.0.3 63792
    dir "/usr/local/bin"
    sentinel known-slave mymaster 10.0.0.4 63793
    sentinel known-slave mymaster 10.0.0.4 63794
    sentinel known-slave mymaster 10.0.0.3 63791
    sentinel known-sentinel mymaster 10.0.0.3 26379 c327be464ef36e670566a0d76c9dc85bac7f33b1
    sentinel known-sentinel mymaster 10.0.0.4 26379 3d43ddea4d4ba8de7dd30e2d332723508f6d4c19
    sentinel known-sentinel mymaster 10.0.0.4 26378 6d134d9a3e53c0cb70de842281de8aaf17a84c00
    sentinel current-epoch 0

通过日志观察故障切换过程

模拟主服务器故障并查看故障切换

[root@master bin]# redis-cli -h 10.0.0.3 -p 6379 shutdown
[root@master bin]# ps -ef|grep redis
    root  2585  1 0 May11 ? 00:00:07 redis-server 10.0.0.3:63792
    root  2590  1 0 May11 ? 00:00:07 redis-server 10.0.0.3:63791
    root 2660   1  0 01:20 ?  00:00:02 redis-sentinel *:26378
    root  2664   1  0 01:20 ?  00:00:02 redis-sentinel *:26379
    root  2676  2479  0 01:30 00:00:00 grep --color=auto redis

此时发现主服务器进程不存在,说明服务有故障

清空原来的日志并查看故障切换过程

[root@slave bin]# > /var/log/redis/sentinel-s3.log       
[root@slave bin]# tail -f /var/log/redis/sentinel-s3.log
    [2669] 12 May 01:30:55.203 # +sdown master mymaster 10.0.0.3 6379
    [2669] 12 May 01:30:55.276 # +new-epoch 1
    [2669] 12 May 01:30:55.280 # +vote-for-leader c327be464ef36e670566a0d76c9dc85bac7f33b1 1
    [2669] 12 May 01:30:56.329 # +odown master mymaster 10.0.0.3 6379 #quorum 4/2
    [2669] 12 May 01:30:57.547 # +switch-master mymaster 10.0.0.3 6379 10.0.0.3 63792
    [2669] 12 May 01:30:57.548 * +slave slave 10.0.0.4:63794 10.0.0.4 63794 @ mymaster 10.0.0.3 63792
    [2669] 12 May 01:30:57.553 * +slave slave 10.0.0.4:63793 10.0.0.4 63793 @ mymaster 10.0.0.3 63792
    [2669] 12 May 01:30:57.556 * +slave slave 10.0.0.3:63791 10.0.0.3 63791 @ mymaster 10.0.0.3 63792
    [2669] 12 May 01:30:57.561 * +slave slave 10.0.0.3:6379 10.0.0.3 6379 @ mymaster 10.0.0.3 63792
    [2669] 12 May 01:31:27.620 # +sdown slave 10.0.0.3:6379 10.0.0.3 6379 @ mymaster 10.0.0.3 63792

可以看出判定master主观下线(+sdown),sentinel选举10.0.0.3 63792为新的主服务器,其它slave自动执行slaveof ,故障转移成功

恢复原主服务器

[root@master bin]# redis-server redis.conf
[root@master bin]# ps -ef|grep redis
    root  2585 1  0 May11 ? 00:00:08 redis-server 10.0.0.3:63792
    root  2590 1  0 May11 ? 00:00:08 redis-server 10.0.0.3:63791
    root  2660 1  0 01:20 ?   00:00:05 redis-sentinel *:26378
    root   2664   1  0 01:20 ?  00:00:05 redis-sentinel *:26379
    root   2683  1  0 01:36 ?   00:00:00 redis-server 10.0.0.3:6379
    root  2689   2479  0 01:36 00:00:00 grep --color=auto redis
[root@slave bin]# tail -f /var/log/redis/sentinel-s3.log
    [2673] 12 May 01:36:21.925 # -sdown slave 10.0.0.3:6379 10.0.0.3 6379 @ mymaster 10.0.0.3 63792

当原来主服务器故障恢复后,自动以从角色加入到集群,并不会抢占主服务器的角色

测试读写分离

[root@master bin]# redis-cli -h 10.0.0.3 -p 63792
    10.0.0.3:63792> get key
        "test"
    10.0.0.3:63792> set key file
        OK
    10.0.0.3:63792> get key
        "file"
[root@master bin]# redis-cli -h 10.0.0.3 -p 6379
    10.0.0.3:6379> get key
        "file"
    10.0.0.3:6379> set key file1
        (error) READONLY You can't write against a read only slave.

说明新主是提升成功的,原来的主故障恢复后已是从服务器,而且也是只读状态,没有破坏之前的主写从读的状态

至此整个布署过程结束,实现了集群监控与自动故障切换、读写分离的功能


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