CentOS-7 Redis主从复制实践笔记记录

环境准备

基于：https://www.jianshu.com/p/c450612c6295安装完成的虚拟机上克隆出新的一个虚拟机做相关测试。

主从服务都安装上了redis环境

主服务器：192.169.74.128
从服务器：182.168.74.129

image.png

1.主服务器redis.conf配置

因为启动的redis的时候，我们的启动方式使用指定的默认配置文件来进行启动的！

[root@localhost ~]# redis-server /usr/local/redis/redis.conf 

（1）所以我们需要修改一下相关启动文件的配置

bind 192.168.4.1 
requirepass 123456

image.png

（2）启动主服务器redis进行测试

[root@localhost ~]# redis-cli -h 192.168.74.128 -p 6379 -a 123456 
192.168.74.128:6379> ping
PONG  #表示成功
192.168.74.128:6379> 

2.从服务器 增加下面两个信息，修改相关的redis.conf配置

(1)配置主服务器的相关信息

slaveof 192.168.74.128 6379
masterauth 123456

image.png

（2）启动从服务器redis进行测试

[root@localhost ~]# redis-cli -h 127.0.0.1 -p 6379 -a 123456
127.0.0.1:6379> ping
PONG # 表示成功
127.0.0.1:6379> 

3.测试主从同步

（1）主服务器写入数据：

[root@localhost ~]# redis-cli -h 192.168.74.128 -p 6379 -a 123456 
192.168.74.128:6379> ping
PONG
192.168.74.128:6379> set xiaozhong 'xiaozhong'
OK
192.168.74.128:6379> keys *
1) "xiaozhong"
192.168.74.128:6379> 

（2）从服务器查看主服务器的写入的数据：

[root@localhost ~]# redis-cli -h 127.0.0.1 -p 6379 -a 123456
127.0.0.1:6379> ping
PONG
127.0.0.1:6379> keys *
1) "xiaozhong"
127.0.0.1:6379> get xiaozhong
"xiaozhong"
127.0.0.1:6379> 

============================================

4.其他情况的测试

第1种：主从服务器都还在存活的情况下，在才服务器上进行写入

[root@localhost ~]# redis-cli -h 127.0.0.1 -p 6379 -a 123456
127.0.0.1:6379> ping
PONG
127.0.0.1:6379> keys *
1) "xiaozhong"
127.0.0.1:6379> get xiaozhong
"xiaozhong"
127.0.0.1:6379> set xiaozhong_congfuwuqi 'congceshi'
(error) READONLY You can't write against a read only slave.
127.0.0.1:6379> 

出现：(error) READONLY You can't write against a read only slave.错误提示!

尝试解决方案：
将从redis设成主redis

redis-cli -h 127.0.0.1 -p 6379 -a 123456 slaveof NO ONE
redis-cli -h 127.0.0.1 -p 6379 -a 123456 set slave-read-only no

---

[root@localhost ~]# redis-cli -h 127.0.0.1 -p 6379 -a 123456
127.0.0.1:6379> ping
PONG
127.0.0.1:6379> keys *
1) "xiaozhong"
127.0.0.1:6379> keys *
1) "xiaozhong"
127.0.0.1:6379> get xiaozhong
"xiaozhong"
127.0.0.1:6379> set xiaozhong_congfuwuqi 'congceshi'
(error) READONLY You can't write against a read only slave.
127.0.0.1:6379> exit
[root@localhost ~]# redis-cli -h 127.0.0.1 -p 6379 -a 123456 slaveof NO ONE
OK
[root@localhost ~]# redis-cli -h 127.0.0.1 -p 6379 -a 123456 set slave-read-only no
OK
[root@localhost ~]# 

重新再进行写入测试：

[root@localhost ~]# redis-cli -h 127.0.0.1 -p 6379 -a 123456 slaveof NO ONE
OK
[root@localhost ~]# redis-cli -h 127.0.0.1 -p 6379 -a 123456 set slave-read-only no
OK
[root@localhost ~]# redis-cli -h 127.0.0.1 -p 6379 -a 123456
127.0.0.1:6379> set xiaozhong_congfuwuqi 'congceshi'
OK
127.0.0.1:6379> 

---

[root@localhost ~]# redis-cli -h 127.0.0.1 -p 6379 -a 123456 slaveof NO ONE
OK
[root@localhost ~]# redis-cli -h 127.0.0.1 -p 6379 -a 123456 set slave-read-only no
OK
[root@localhost ~]# redis-cli -h 127.0.0.1 -p 6379 -a 123456
127.0.0.1:6379> set xiaozhong_congfuwuqi 'congceshi'
OK
127.0.0.1:6379> keys *
1) "xiaozhong_congfuwuqi"
2) "slave-read-only"
3) "xiaozhong"
127.0.0.1:6379> 

查看主服务器的情况：
从数据库写入的数据在主服务器查看是没有同步过来！--（可能的原因因为我们配置的是主从模式）

[root@localhost ~]# redis-cli -h 192.168.74.128 -p 6379 -a 123456 
192.168.74.128:6379> ping
PONG
192.168.74.128:6379> set xiaozhong 'xiaozhong'
OK
192.168.74.128:6379> keys *
1) "xiaozhong"
192.168.74.128:6379> keys *
1) "xiaozhong"
192.168.74.128:6379> 

第2种：主服务器挂了的情况下，从服务器（升级为主节点后，继续向从服务器（slave）写入）
（1）停止主服务器

redis-cli -h 192.168.74.128 -p 6379 -a 123456 shutdown
或
[root@localhost ~]# ps -ef|grep redis
root       2918      1  0 03:29 ?        00:00:06 redis-server 192.168.74.128:6379
root       3097   2354  0 04:56 pts/0    00:00:00 grep --color=auto redis
[root@localhost ~]# kill - 9 2918

---

192.168.74.128:6379> exit
[root@localhost ~]# ps -ef|grep redis
root       2918      1  0 03:29 ?        00:00:06 redis-server 192.168.74.128:6379
root       3097   2354  0 04:56 pts/0    00:00:00 grep --color=auto redis
[root@localhost ~]# kill - 9 2918
-bash: kill: : invalid signal specification
[root@localhost ~]# kill -9 2918
[root@localhost ~]# 

（2）从服务器在继续写入数据

[root@localhost ~]# redis-cli -h 127.0.0.1 -p 6379 -a 123456
127.0.0.1:6379> set xiaozhong_congfuwuqi 'congceshi'
OK
127.0.0.1:6379> keys *
1) "xiaozhong_congfuwuqi"
2) "slave-read-only"
3) "xiaozhong"
127.0.0.1:6379> set xiaozhong_congfuwuqi2 'congceshi2'
OK
127.0.0.1:6379> keys *
1) "xiaozhong_congfuwuqi"
2) "slave-read-only"
3) "xiaozhong_congfuwuqi2"
4) "xiaozhong"
127.0.0.1:6379> 

（3）主服务器恢复并写入数据（查看数据）

[root@localhost ~]# redis-server /usr/local/redis/redis.conf 
[root@localhost ~]# redis-cli -h 192.168.74.128 -p 6379 -a 123456 
192.168.74.128:6379> set xiaozhong_zhufuwuqi 'ceshi'
OK
192.168.74.128:6379> keys *
1) "xiaozhong"
2) "xiaozhong_zhufuwuqi"
192.168.74.128:6379> 

（4）再次查看从服务器数据
问题：发现主服务器新写入的数据，从服务器没有写入？
具体是什么问题呐？

[root@localhost ~]# redis-cli -h 127.0.0.1 -p 6379 -a 123456
127.0.0.1:6379> set xiaozhong_congfuwuqi 'congceshi'
OK
127.0.0.1:6379> keys *
1) "xiaozhong_congfuwuqi"
2) "slave-read-only"
3) "xiaozhong"
127.0.0.1:6379> set xiaozhong_congfuwuqi2 'congceshi2'
OK
127.0.0.1:6379> keys *
1) "xiaozhong_congfuwuqi"
2) "slave-read-only"
3) "xiaozhong_congfuwuqi2"
4) "xiaozhong"
127.0.0.1:6379> keys *
1) "xiaozhong_congfuwuqi"
2) "slave-read-only"
3) "xiaozhong_congfuwuqi2"
4) "xiaozhong"
127.0.0.1:6379> 

(5)退出从服务器重新进入，也还是没有主服务器最新的数据

127.0.0.1:6379> exit
[root@localhost ~]# redis-cli -h 127.0.0.1 -p 6379 -a 123456
127.0.0.1:6379> keys *
1) "xiaozhong_congfuwuqi"
2) "slave-read-only"
3) "xiaozhong_congfuwuqi2"
4) "xiaozhong"
127.0.0.1:6379> 

(6)重新启动从服务器
发现以前写入的数据，丢失了！主服务器的新写入的数据也写入了！

[root@localhost ~]# ps -ef|grep redis
root       2799      1  0 03:26 ?        00:00:08 redis-server 0.0.0.0:6379
root       3041   2311  0 05:06 pts/0    00:00:00 grep --color=auto redis
[root@localhost ~]# kill -9 2799
[root@localhost ~]# ps -ef|grep redis
root       3043   2311  0 05:06 pts/0    00:00:00 grep --color=auto redis
[root@localhost ~]# redis-server /usr/local/redis/redis.conf 
[root@localhost ~]# redis-cli -h 127.0.0.1 -p 6379 -a 123456
127.0.0.1:6379> keys *
1) "xiaozhong_zhufuwuqi"
2) "xiaozhong"
127.0.0.1:6379>