redis主从环境配置

q968

　　本文介绍redis主从环境下的手工failover操作及排错过程，实现主实例宕机的时候，将从实例提升为主实例，继续写入数据；等到原主实例恢复后，同步原从实例上的数据完成后，恢复初始的主从实例角色！
　　环境介绍
　　操作系统版本均为：rhel5.4 64bit
　　redis版本：2.6.4
　　redis实例端口均为：6379
　　redis实例密码均为：123
　　主实例为server11(192.168.1.112)
　　从实例为server12(192.168.1.113)
　　一：未配置持久化情况下的手工切换
　　1：正常情况下，server11为主实例，server12为从实例，数据同步正常
　　01.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123
　　02.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 info |grep -A 3 'Replication'
　　03.# Replication
　　04.role:master
　　05.connected_slaves:1
　　06.slave0:192.168.1.113,6379,online
　　07.
　　08.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 config get save
　　09.1) "save"
　　10.2) ""
　　11.
　　12.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 config get save
　　13.1) "save"
　　14.2) ""
　　15.
　　16.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 set 5 e
　　17.OK
　　18.
　　19.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 get 5
　　20."e"
　　21.
　　22.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 get 5  23."e" 2：当主实例挂掉的时候，从实例可以正常查询，但无法写入数据
　　01.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 shutdown
　　02.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 get 5
　　03.Could not connect to Redis at 192.168.1.112:6379: Connection refused
　　04.
　　05.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 get 5
　　06."e"
　　07.[root@server12 ~]#  /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 set 6 f  08.(error) READONLY You can't write against a read only slave. 3：将从实例提升为主实例，从而实现数据写入
　　01.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 SLAVEOF NO ONE
　　02.OK
　　03.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 info |grep -A 3 'Replication'
　　04.# Replication
　　05.role:master
　　06.connected_slaves:0
　　07.
　　08.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 get 5
　　09."e"
　　10.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 set 6 f
　　11.OK
　　12.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 get 6
　　13."f" 4:主实例恢复后尝试从server12实例上获取最新的数据，实际测试表明这种方法不可行，最终导致server11和server12的数据不一致，如果强行恢复初始实例角色，则会导致数据丢失
　　01.[root@server11 ~]# /usr/local/redis2/bin/redis-server /usr/local/redis2/etc/redis.conf
　　02.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 info |grep -A 3 'Replication'
　　03.# Replication
　　04.role:master
　　05.connected_slaves:0
　　06.
　　07.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123  get 5
　　08.(nil)
　　09.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123  get 6
　　10.(nil)
　　11.
　　12.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123  get 5
　　13."e"
　　14.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123  get 6
　　15."f"
　　16.
　　17.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -p 6379 -a 123 SLAVEOF 192.168.1.113 6379
　　18.OK
　　19.
　　20.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 info |grep -A 10 'Replication'
　　21.# Replication
　　22.role:slave
　　23.master_host:192.168.1.113
　　24.master_port:6379
　　25.master_link_status:down
　　26.master_last_io_seconds_ago:-1
　　27.master_sync_in_progress:0
　　28.master_link_down_since_seconds:517
　　29.slave_priority:100
　　30.slave_read_only:1
　　31.connected_slaves:0
　　32.
　　33.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 info |grep -A 3 'Replication'
　　34.# Replication
　　35.role:master
　　36.connected_slaves:0
　　37.
　　38.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 get 5
　　39.(nil)
　　40.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 get 6
　　41.(nil)
　　42.
　　43.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 get 6
　　44."f"
　　45.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 get 5
　　46."e" 二：开启从实例快照持久化下的测试
　　1：恢复原测试环境后，开启从实例的快照持久化，因为是测试环境，所以设置60秒内如果有1条数据变更则保持一次快照
　　01.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 config get save  02.1) "save"  03.2) ""  04. 05.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 config get save  06.1) "save"  07.2) "60 1"  08. 09.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 info |grep -A 3 'Replication'  10.# Replication  11.role:master  12.connected_slaves:1  13.slave0:192.168.1.113,6379,online  14. 15.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 info |grep -A 3 'Replication'  16.# Replication  17.role:slave  18.master_host:192.168.1.112  19.master_port:6379 2：写入测试数据主从环境数据是否同步正常
　　01.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 set 5 e  02.OK  03. 04.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 get 5  05."e"  06. 07.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 get 5  08."e" 3：模拟主实例宕机，手动将从实例提升为主实例，继续写入新数据
　　01.[root@server11 ~]# killall -9 redis-server  02.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 info |grep -A 3 'Replication'  03.Could not connect to Redis at 192.168.1.112:6379: Connection refused  04. 05.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 get 5  06."e"  07.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 set 6 f  08.(error) READONLY You can't write against a read only slave  09. 10.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 slaveof no one  11.OK  12.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 info |grep -A 3 'Replication'  13.# Replication  14.role:master  15.connected_slaves:0  16. 17.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 get 5  18."e"  19. 20.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 set 6 f  21.OK  22. 23.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 get 6  24."f" 4:原主实例恢复后的数据同步及角色复原,这里同步数据采取将从实例的快照文件复制到主实例的方式实现
　　01.[root@server12 ~]# scp /usr/local/redis2/slave_dump.rdb  server11:/usr/local/redis2/master_dump.rdb  02.[root@server11 ~]# /usr/local/redis2/bin/redis-server /usr/local/redis2/etc/redis.conf   03.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 info |grep -A 2 'Replication'  04.# Replication  05.role:master  06.connected_slaves:0  07.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 get 5  08."e"  09.[root@server11 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 get 6  10."f"  11. 12.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 slaveof 192.168.1.112 6379  13.OK  14.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 info |grep -A 10 'Replication'  15.# Replication  16.role:slave  17.master_host:192.168.1.112  18.master_port:6379  19.master_link_status:up  20.master_last_io_seconds_ago:1  21.master_sync_in_progress:0  22.slave_priority:100  23.slave_read_only:1  24.connected_slaves:0  25.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 get 5  26."e"  27.[root@server12 ~]# /usr/local/redis2/bin/redis-cli -h 192.168.1.113 -a 123 get 6  28."f  29. 30.[root@server11 ~]#  /usr/local/redis2/bin/redis-cli -h 192.168.1.112 -a 123 info |grep -A 3 'Replication'  31.# Replication  32.role:master  33.connected_slaves:1  34.slave0:192.168.1.113,6379,online