Redis的复制（Master/Slave）、主从复制、读写分离 （下）

哨兵模式（就是反客为主的自动版）

　　能够自动监控主机是否故障，如果故障了根据投票数自动将从机变成主机

　　1创建哨兵文件

touch sentinel.conf
[root@localhost myredis]# ls -l
总用量
-rw-r--r--.  root root     7月   : dump6379.rdb
-rw-r--r--.  root root     7月   : dump6380.rdb
-rw-r--r--.  root root  8月    : redis6379.conf
-rw-r--r--.  root root  7月   : redis6380.conf
-rw-r--r--.  root root  7月   : redis6381.conf
-rw-r--r--.  root root  7月   : redis_aof.conf
-rw-r--r--.  root root  7月   : redis.conf
-rw-r--r--.  root root      8月    : sentinel.conf

　　2、给哨兵文件添加监听内容

sentinel monitor 被监控数据库名字（自己起名字） 127.0.0.1 6379 1：这里的这个数字1，表示主机死掉以后slaver投票看让谁接替称为主机，谁票数多多谁是主机。

sentinel monitor host6379 127.0.0.1  

　　3、启动哨兵

[root@localhost myredis]# redis-sentinel /myredis/sentinel.conf
:X  Aug ::20.908 * Increased maximum number of open files to  (it was originally set to ).
                _._
           _.-``__ ''-._
      _.-``    `.  `_.  ''-._           Redis 3.0. (/)  bit
  .-`` .-```.  ```\/    _.,_ ''-._
 (    '      ,       .-`  | `,    )     Running in sentinel mode
 |`-._`-...-` __...-.``-._|'` _.-'|     Port:
 |    `-._   `._    /     _.-'    |     PID: 22600
  `-._    `-._  `-./  _.-'    _.-'
 |`-._`-._    `-.__.-'    _.-'_.-'|
 |    `-._`-._        _.-'_.-'    |           http://redis.io
  `-._    `-._`-.__.-'_.-'    _.-'
 |`-._`-._    `-.__.-'    _.-'_.-'|
 |    `-._`-._        _.-'_.-'    |
  `-._    `-._`-.__.-'_.-'    _.-'
      `-._    `-.__.-'    _.-'
          `-._        _.-'
              `-.__.-'                                               

:X  Aug ::20.910 # WARNING: The TCP backlog setting of  cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of .
:X  Aug ::20.910 # Sentinel runid is 31cfb89ac4fe6085784e0541972261ff7f09f339
:X  Aug ::20.910 # +monitor master host6379 127.0.0.1  quorum
:X  Aug ::20.912 * +slave slave 127.0.0.1: 127.0.0.1  @ host6379 127.0.0.1
:X  Aug ::20.914 * +slave slave 127.0.0.1: 127.0.0.1  @ host6379 127.0.0.1 

　　4、主机关闭，哨兵会自动选举出主机

127.0.0.1:> info replication
# Replication
role:master
connected_slaves:
slave0:ip=127.0.0.1,port=,state=online,offset=,lag=
master_repl_offset:
repl_backlog_active:
repl_backlog_size:
repl_backlog_first_byte_offset:
repl_backlog_histlen:
127.0.0.1:> set k44
OK

127.0.0.1:> info replication
# Replication
role:slave
master_host:127.0.0.1
master_port:
master_link_status:up
master_last_io_seconds_ago:
master_sync_in_progress:
slave_repl_offset:
slave_priority:
slave_read_only:
connected_slaves:
master_repl_offset:
repl_backlog_active:
repl_backlog_size:
repl_backlog_first_byte_offset:
repl_backlog_histlen:
127.0.0.1:> get k44
""

　　5、前面主机回来（前主机作为Slaver）

127.0.0.1:> info replication
# Replication
role:slave
master_host:127.0.0.1
master_port:
master_link_status:up
master_last_io_seconds_ago:
master_sync_in_progress:
slave_repl_offset:
slave_priority:
slave_read_only:
connected_slaves:
master_repl_offset:
repl_backlog_active:
repl_backlog_size:
repl_backlog_first_byte_offset:
repl_backlog_histlen:
127.0.0.1:> get k44
""