Redis主从复制、哨兵模式

1.部署主从

环境:主IP:10.0.0.15,端口6379;从IP:10.0.0.16,端口6379.

原理:基于RDB持久化的功能来实现主从复制的功能.

a.linux-redis1(10.0.0.15)

cd /usr/local/redis/
grep "^[a-Z]" redis.conf  # 列出几个修改过的配置
bind 10.0.0.15
protected-mode no
port 6379
daemonize yes
loglevel notice
logfile /usr/local/redis/logs/redis.log
databases 16
save 900 1
save 300 10
save 60 10000
dir /data/redis

b.linux-redis2(10.0.0.16)

cd /usr/local/redis/
grep "^[a-Z]" redis.conf  # 其余与上面的配置保持一致
bind 10.0.0.16
slaveof  10.0.0.15 6379

# 启动脚本
cat /usr/lib/systemd/system/redis.service

IP=`ifconfig eth0 | awk -F"[ ]+" 'NR==2{print $3}'`
[Unit]
Description=The redis-server Process Manager
After=network.target

[Service]
ExecStart=/usr/local/redis/src/redis-server /usr/local/redis/redis.conf --daemonize no
ExecStop=/usr/local/redis/src/redis-cli -h $IP shutdown

[Install]
WantedBy=multi-user.target

systemctl daemon-reload
systemctl enable redis
systemctl start redis

c.测试

主redis上输入数据

从redis上获取数据

此时的从redis只能读取数据,不能写入,主redis宕机之后,也不能写入,手动切换:

主redis上输入shutdown,从redis上输入slaveof no one,就可以写入数据了;

此时如果有其他的从redis,则输入slaveof 10.0.0.16 6379即可更换主redis;

此时如果刚才宕掉的redis又恢复了,则还是输入slaveof 10.0.0.16 6379,由主变成从.

2.利用哨兵模式实现主从自动切换

cat sentinel.conf  # 当启动模式之后,这个配置文件中会自动增加从redis的信息
port 26379
dir "/tmp"
sentinel myid b84f8aea247ad5f7ea48c6a4921d0cca5ffc915f
sentinel monitor mymaster 10.0.0.15 6379 1
sentinel down-after-milliseconds mymaster 10000
sentinel failover-timeout mymaster 18000

./src/redis-sentinel sentinel.conf
# Sentinel ID is b84f8aea247ad5f7ea48c6a4921d0cca5ffc915f
# +monitor master mymaster 10.0.0.15 6379 quorum 1
* +slave slave 10.0.0.16:6379 10.0.0.16 6379 @ mymaster 10.0.0.15 6379
* +slave slave 10.0.0.17:6379 10.0.0.17 6379 @ mymaster 10.0.0.15 6379

# 配置文件中自动生成了这些内容
# Generated by CONFIG REWRITE
sentinel config-epoch mymaster 0
sentinel leader-epoch mymaster 0
sentinel known-slave mymaster 10.0.0.16 6379
sentinel known-slave mymaster 10.0.0.17 6379
sentinel current-epoch 0

在10.0.0.15上停掉主redis:redis-cli -h 10.0.0.15 shutdown

主redis宕了,其余redis开始进行选举,在经过选举之后,其中的一个从redis会变为主redis,通过日志或者配置文件都可以看出来,此时谁是master.

cat sentinel.conf
port 26379
dir "/tmp"
sentinel myid b84f8aea247ad5f7ea48c6a4921d0cca5ffc915f
sentinel monitor mymaster 10.0.0.17 6379 1
sentinel down-after-milliseconds mymaster 10000
sentinel failover-timeout mymaster 18000
# Generated by CONFIG REWRITE
sentinel config-epoch mymaster 1
sentinel leader-epoch mymaster 1
sentinel known-slave mymaster 10.0.0.15 6379
sentinel known-slave mymaster 10.0.0.16 6379
sentinel current-epoch 1

# 此时启动10.0.0.15上的redis,它也只能"俯首称臣"
convert-to-slave slave 10.0.0.15:6379 10.0.0.15 6379 @ mymaster 10.0.0.17 6379

# 在配置文件sentinel.conf中加上这三行比较合适
daemonize yes
protected-mode no
logfile "/var/log/sentinel.log"

Redis主从利用Keepalived自动切换:http://blog.51cto.com/tryingstuff/2093119