Redis主从同步

主从同步原理

1. 从服务器向主服务器发送 SYNC 命令。
2. 接到 SYNC 命令的主服务器会调用BGSAVE 命令，创建一个 RDB 文件，并使用缓冲区记录接下来执行的所有写命令。
3. 当主服务器执行完 BGSAVE 命令时，它会向从服务器发送 RDB 文件，而从服务器则会接收并载入这个文件。
4. 主服务器将缓冲区储存的所有写命令发送给从服务器执行。

 

修改配置文件

vim redis-6379.confport 6379
daemonize yes
pidfile /data/6379/redis.pid
loglevel notice
logfile "/data/6379/redis.log"
protected-mode yes
# RDB配置
dir /data/6379
dbfilename dbmp.rdb
save 900 1
save 300 10
save 60 10000# AOF配置
#appendonly yes
#appendfsync everysec

vim redis-6380.confport 6380
daemonize yes
pidfile /data/6380/redis.pid
loglevel notice
logfile "/data/6380/redis.log"
protected-mode yes
# RDB配置
dir /data/6380
dbfilename dbmp.rdb
save 900 1
save 300 10
save 60 10000# 主从同步
slaveof 127.0.0.1 6379# AOF配置
#appendonly yes
#appendfsync everysec

vim redis-6381.confport 6381
daemonize yes
pidfile /data/6381/redis.pid
loglevel notice
logfile "/data/6381/redis.log"
protected-mode yes
# RDB配置
dir /data/6381
dbfilename dbmp.rdb
save 900 1
save 300 10
save 60 10000# 主从同步
slaveof 127.0.0.1 6379# AOF配置
#appendonly yes
#appendfsync everysec

 

启动三个实例

[root@localhost redis-4.0.12]# redis-server redis-6379.conf 
[root@localhost redis-4.0.12]# redis-server redis-6380.conf 
[root@localhost redis-4.0.12]# redis-server redis-6381.conf 

 

查看主从状态

# 6379
[root@localhost ~]# redis-cli -p 6379 info replication
# Replication
role:master
connected_slaves:2
slave0:ip=127.0.0.1,port=6380,state=online,offset=196,lag=1
slave1:ip=127.0.0.1,port=6381,state=online,offset=196,lag=0
master_replid:0f3b54ebd09f5cc585c33c9872f005f1437d25e1
master_replid2:0000000000000000000000000000000000000000
master_repl_offset:196
second_repl_offset:-1
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:1
repl_backlog_histlen:196

# 6380
[root@localhost ~]# redis-cli -p 6380 info replication
# Replication
role:slave
master_host:127.0.0.1
master_port:6379
master_link_status:up
master_last_io_seconds_ago:1
master_sync_in_progress:0
slave_repl_offset:210
slave_priority:100
slave_read_only:1
connected_slaves:0
master_replid:0f3b54ebd09f5cc585c33c9872f005f1437d25e1
master_replid2:0000000000000000000000000000000000000000
master_repl_offset:210
second_repl_offset:-1
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:1
repl_backlog_histlen:210

# 6381
[root@localhost ~]# redis-cli -p 6381 info replication
# Replication
role:slave
master_host:127.0.0.1
master_port:6379
master_link_status:up
master_last_io_seconds_ago:0
master_sync_in_progress:0
slave_repl_offset:224
slave_priority:100
slave_read_only:1
connected_slaves:0
master_replid:0f3b54ebd09f5cc585c33c9872f005f1437d25e1
master_replid2:0000000000000000000000000000000000000000
master_repl_offset:224
second_repl_offset:-1
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:1
repl_backlog_histlen:224

 

方式二（不修改配置文件，重启服务后失效）：

操作

127.0.0.1:6381> slaveof 127.0.0.1 6379
127.0.0.1:6380> slaveof 127.0.0.1 6379

 

查看状态

[root@localhost ~]# redis-cli -p 6379
127.0.0.1:6379> info replication
# Replication
role:master
connected_slaves:0
master_replid:d0fff3d6587307c4d3072cc92a6e16bdd91e291d
master_replid2:0000000000000000000000000000000000000000
master_repl_offset:0
second_repl_offset:-1
repl_backlog_active:0
repl_backlog_size:1048576
repl_backlog_first_byte_offset:0
repl_backlog_histlen:0

[root@localhost redis-4.0.12]# redis-cli -p 6380
127.0.0.1:6380> info replication
# Replication
role:master
connected_slaves:0
master_replid:a9960a82a571793eae37e322143a3ef1caee75e5
master_replid2:0000000000000000000000000000000000000000
master_repl_offset:0
second_repl_offset:-1
repl_backlog_active:0
repl_backlog_size:1048576
repl_backlog_first_byte_offset:0
repl_backlog_histlen:0

127.0.0.1:6381> info replication
# Replication
role:master
connected_slaves:0
master_replid:fd7b3f7a0c98a0dcd2fb3d4a7a8b7fde6e09238b
master_replid2:0000000000000000000000000000000000000000
master_repl_offset:0
second_repl_offset:-1
repl_backlog_active:0
repl_backlog_size:1048576
repl_backlog_first_byte_offset:0
repl_backlog_histlen:0