阅读目录
1.Linux服务器列表
使用4台CentOS Linux服务器搭建环境，其IP地址如下：
192.168.110.100192.168.110.101192.168.110.102192.168.110.103
2.Redis服务部署环境
192.168.110.100
启动多个Redis sentinel服务，构成Redis sentinel集群
192.168.110.101
启动Redis服务，设置成主节点
192.168.110.102
启动Redis服务，设置成192.168.110.101的从节点
192.168.110.103
启动Redis服务，设置成192.168.110.101的从节点
1.修改redis.conf配置文件
主节点的redis配置文件使用默认的配置文件就可以了，从节点的redis配置文件修改如下：
# 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.## 主从同步。通过 slaveof 配置来实现Redis实例的备份。# 注意，这里是本地从远端复制数据。也就是说，本地可以有不同的数据库文件、绑定不同的IP、监听不同的端口。## slaveof <masterip> <masterport>slaveof 192.168.110.101 6379
注意:两台从节点都要改。
2.启动Redis主从集群
先启动192.168.110.101主节点，使用默认配置，脚本：
[lizhiwei@localhost bin]$ ./redis-server
再启动192.168.110.102和192.168.110.103从节点，使用刚才的配置，脚本：
./redis-server redis.conf
3.查看集群
192.168.110.101主节点Replication信息
[lizhiwei@localhost bin]$ ./redis-cli -h 192.168.110.101 info Replication# Replicationrole:masterconnected_slaves:2slave0:ip=192.168.110.102,port=6379,state=online,offset=659,lag=1slave1:ip=192.168.110.103,port=6379,state=online,offset=659,lag=0master_repl_offset:659repl_backlog_active:1repl_backlog_size:1048576repl_backlog_first_byte_offset:2repl_backlog_histlen:658
192.168.110.102从节点Replication信息
[lizhiwei@localhost bin]$ ./redis-cli -h 192.168.110.102 info Replication # Replicationrole:slavemaster_host:192.168.110.101master_port:6379master_link_status:upmaster_last_io_seconds_ago:3master_sync_in_progress:0slave_repl_offset:701slave_priority:100slave_read_only:1connected_slaves:0master_repl_offset:0repl_backlog_active:0repl_backlog_size:1048576repl_backlog_first_byte_offset:0repl_backlog_histlen:0
192.168.110.103从节点Replication信息
[lizhiwei@localhost bin]$ ./redis-cli -h 192.168.110.103 info Replication # Replicationrole:slavemaster_host:192.168.110.101master_port:6379master_link_status:upmaster_last_io_seconds_ago:9master_sync_in_progress:0slave_repl_offset:715slave_priority:100slave_read_only:1connected_slaves:0master_repl_offset:0repl_backlog_active:0repl_backlog_size:1048576repl_backlog_first_byte_offset:0repl_backlog_histlen:0
此时，存储到192.168.110.101主节点的数据，在从节点中都可以查询到。从节点会备份主节点的数据。
1.创建sentinel.conf配置文件
port 26379# sentinel announce-ip <ip># sentinel announce-port <port>dir /tmp################################# master001 #################################sentinel monitor master001 192.168.110.101 6379 2# sentinel auth-pass <master-name> <password>sentinel down-after-milliseconds master001 30000sentinel parallel-syncs master001 1sentinel failover-timeout master001 180000# sentinel notification-script <master-name> <script-path># sentinel client-reconfig-script <master-name> <script-path># 可以配置多个master节点################################# master002 #################################
配置文件说明：
1. port :当前Sentinel服务运行的端口
2. dir : Sentinel服务运行时使用的临时文件夹
3.sentinel monitor master001 192.168.110.101 6379 2:Sentinel去监视一个名为master001的主redis实例，这个主实例的IP地址为本机地址192.168.110.101，端口号为6379，而将这个主实例判断为失效至少需要2个 Sentinel进程的同意，只要同意Sentinel的数量不达标，自动failover就不会执行
4.sentinel down-after-milliseconds master001 30000:指定了Sentinel认为Redis实例已经失效所需的毫秒数。当实例超过该时间没有返回PING，或者直接返回错误，那么Sentinel将这个实例标记为主观下线。只有一个 Sentinel进程将实例标记为主观下线并不一定会引起实例的自动故障迁移：只有在足够数量的Sentinel都将一个实例标记为主观下线之后，实例才会被标记为客观下线，这时自动故障迁移才会执行
5.sentinel parallel-syncs master001 1：指定了在执行故障转移时，最多可以有多少个从Redis实例在同步新的主实例，在从Redis实例较多的情况下这个数字越小，同步的时间越长，完成故障转移所需的时间就越长
6.sentinel failover-timeout master001 180000：如果在该时间（ms）内未能完成failover操作，则认为该failover失败
7.sentinel notification-script <master-name> <script-path>：指定sentinel检测到该监控的redis实例指向的实例异常时，调用的报警脚本。该配置项可选，但是很常用
2.启动sentinel集群
创建3个sentinel.conf配置文件：sentinel001.conf、sentinel002.conf、sentinel003.conf并修改端口号分别为：26379、36379、46379，并启动服务：
./redis-sentinel sentinel001.conf./redis-sentinel sentinel002.conf./redis-sentinel sentinel003.conf
启动三个sentinel服务后会在其控制台看到如下信息：
./redis-sentinel sentinel001.conf，端口：26379
[7743] 01 Oct 06:20:38.162 # Sentinel runid is ba6c42e1accc31290e11d5876275e1562564295d[7743] 01 Oct 06:20:38.162 # +monitor master master001 192.168.110.101 6379 quorum 2[7743] 01 Oct 06:20:39.110 * +slave slave 192.168.110.102:6379 192.168.110.102 6379 @ master001 192.168.110.101 6379[7743] 01 Oct 06:20:39.111 * +slave slave 192.168.110.103:6379 192.168.110.103 6379 @ master001 192.168.110.101 6379[7743] 01 Oct 06:25:07.595 * +sentinel sentinel 192.168.110.100:36379 192.168.110.100 36379 @ master001 192.168.110.101 6379[7743] 01 Oct 06:26:11.170 * +sentinel sentinel 192.168.110.100:46379 192.168.110.100 46379 @ master001 192.168.110.101 6379
./redis-sentinel sentinel002.conf，端口：36379
[7795] 01 Oct 06:25:05.538 # Sentinel runid is 52c14768b15837fb601b26328acf150c6bd30682[7795] 01 Oct 06:25:05.538 # +monitor master master001 192.168.110.101 6379 quorum 2[7795] 01 Oct 06:25:06.505 * +slave slave 192.168.110.102:6379 192.168.110.102 6379 @ master001 192.168.110.101 6379[7795] 01 Oct 06:25:06.515 * +slave slave 192.168.110.103:6379 192.168.110.103 6379 @ master001 192.168.110.101 6379[7795] 01 Oct 06:25:07.557 * +sentinel sentinel 192.168.110.100:26379 192.168.110.100 26379 @ master001 192.168.110.101 6379[7795] 01 Oct 06:26:11.168 * +sentinel sentinel 192.168.110.100:46379 192.168.110.100 46379 @ master001 192.168.110.101 6379
./redis-sentinel sentinel003.conf，端口：46379
[7828] 01 Oct 06:26:09.076 # Sentinel runid is c8509594be4a36660b2122b3b81f4f74060c9b04[7828] 01 Oct 06:26:09.076 # +monitor master master001 192.168.110.101 6379 quorum 2[7828] 01 Oct 06:26:10.063 * +slave slave 192.168.110.102:6379 192.168.110.102 6379 @ master001 192.168.110.101 6379[7828] 01 Oct 06:26:10.071 * +slave slave 192.168.110.103:6379 192.168.110.103 6379 @ master001 192.168.110.101 6379[7828] 01 Oct 06:26:11.516 * +sentinel sentinel 192.168.110.100:26379 192.168.110.100 26379 @ master001 192.168.110.101 6379[7828] 01 Oct 06:26:11.674 * +sentinel sentinel 192.168.110.100:36379 192.168.110.100 36379 @ master001 192.168.110.101 6379
每个sentinel服务能知道其他所有的服务！
1.停止192.168.110.101主节点
停止192.168.110.101Redis主节点后，在查看Replication信息如下：
[lizhiwei@localhost bin]$ ./redis-cli -h 192.168.110.101 info Replication Could not connect to Redis at 192.168.110.101:6379: Connection refused[lizhiwei@localhost bin]$ ./redis-cli -h 192.168.110.102 info Replication # Replicationrole:slavemaster_host:192.168.110.103master_port:6379master_link_status:upmaster_last_io_seconds_ago:1master_sync_in_progress:0slave_repl_offset:29128slave_priority:100slave_read_only:1connected_slaves:0master_repl_offset:0repl_backlog_active:0repl_backlog_size:1048576repl_backlog_first_byte_offset:0repl_backlog_histlen:0[lizhiwei@localhost bin]$ ./redis-cli -h 192.168.110.103 info Replication # Replicationrole:masterconnected_slaves:1slave0:ip=192.168.110.102,port=6379,state=online,offset=30456,lag=1master_repl_offset:30456repl_backlog_active:1repl_backlog_size:1048576repl_backlog_first_byte_offset:2repl_backlog_histlen:30455[lizhiwei@localhost bin]$
发现192.168.110.101Redis主节点已经不能连接，192.168.110.103成了主节点！
2.再启动192.168.110.101主节点
再启动192.168.110.101Redis主节点后，在查看Replication信息如下：
### 启动脚本，仍然使用默认配置
[lizhiwei@localhost bin]$ ./redis-server
[lizhiwei@localhost bin]$ ./redis-cli -h 192.168.110.101 info Replication
# Replication
role:slave
master_host:192.168.110.103
master_port:6379
master_link_status:up
master_last_io_seconds_ago:1
master_sync_in_progress:0
slave_repl_offset:57657
slave_priority:100
slave_read_only:1
connected_slaves:0
master_repl_offset:0
repl_backlog_active:0
repl_backlog_size:1048576
repl_backlog_first_byte_offset:0
repl_backlog_histlen:0
[lizhiwei@localhost bin]$ ./redis-cli -h 192.168.110.102 info Replication
# Replication
role:slave
master_host:192.168.110.103
master_port:6379
master_link_status:up
master_last_io_seconds_ago:0
master_sync_in_progress:0
slave_repl_offset:60751
slave_priority:100
slave_read_only:1
connected_slaves:0
master_repl_offset:0
repl_backlog_active:0
repl_backlog_size:1048576
repl_backlog_first_byte_offset:0
repl_backlog_histlen:0
[lizhiwei@localhost bin]$ ./redis-cli -h 192.168.110.103 info Replication
# Replication
role:master
connected_slaves:2
slave0:ip=192.168.110.102,port=6379,state=online,offset=63247,lag=1
slave1:ip=192.168.110.101,port=6379,state=online,offset=63247,lag=1
master_repl_offset:63393
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:2
repl_backlog_histlen:63392
[lizhiwei@localhost bin]$
发现192.168.110.101节点启动后还再集群中，只不过成了从节点，192.168.110.103仍然是主节点，但是现在又有两个从节点了！
3.只留下一个sentinel服务，再停止192.168.110.103主节点，查看Redis集群是否出现新的主节点
停止sentinel服务，只留下一个sentinel服务，再停止Redis主节点，查看Replication信息如下：
[lizhiwei@localhost bin]$ ./redis-cli -h 192.168.110.101 info Replication # Replicationrole:slavemaster_host:192.168.110.103master_port:6379master_link_status:downmaster_last_io_seconds_ago:-1master_sync_in_progress:0slave_repl_offset:184231master_link_down_since_seconds:43slave_priority:100slave_read_only:1connected_slaves:0master_repl_offset:0repl_backlog_active:0repl_backlog_size:1048576repl_backlog_first_byte_offset:0repl_backlog_histlen:0[lizhiwei@localhost bin]$ ./redis-cli -h 192.168.110.102 info Replication # Replicationrole:slavemaster_host:192.168.110.103master_port:6379master_link_status:downmaster_last_io_seconds_ago:-1master_sync_in_progress:0slave_repl_offset:184231master_link_down_since_seconds:52slave_priority:100slave_read_only:1connected_slaves:0master_repl_offset:0repl_backlog_active:0repl_backlog_size:1048576repl_backlog_first_byte_offset:0repl_backlog_histlen:0[lizhiwei@localhost bin]$ ./redis-cli -h 192.168.110.103 info Replication Could not connect to Redis at 192.168.110.103:6379: Connection refused
发现192.168.110.103主节点已经不能连接了，也不存在Redis主节点，集群中无主节点了！！！分析原因是：sentinel.conf配置的sentinel monitor master001 192.168.110.101 6379 2最后一个参数是2导致，若是但节点此配置的最后一个参数要使用是1。(此原因我已证实)
注意：在生产环境下建议sentinel节点的数量能在3个以上，并且最好不要在同一台机器上(使用同一网卡)。
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本文出自 “梦想照进现实” 博客，请务必保留此出处http://lookingdream.blog.51cto.com/5177800/1812864
原文地址：http://lookingdream.blog.51cto.com/5177800/1812864
