Redis主从搭建，redis主从

Redis主从搭建，redis主从

原创文章，转载请注明出处：http://www.huyanping.cn/?p=259
作者：Jenner

1

redis安装方法见：初识Redis——邂逅

安装环境：

[root@localhost redis]# redis-server --version
Redis server v=2.8.7 sha=00000000:0 malloc=jemalloc-3.2.0 bits=32 build=df8b796b6fcf0127
[root@localhost redis]# cat /proc/version
Linux version 2.6.18-92.el5 (mockbuild@builder16.centos.org) (gcc version 4.1.2 20071124 (Red Hat 4.1.2-42)) #1 SMP Tue Jun 10 18:49:47 EDT 2008

1、复制配置文件

#master配置文件
cp redis.conf redis-master.conf
#slave配置文件
cp redis.conf redis-slave.conf
#备份配置文件
cp redis.conf redis-bak.conf

2、修改配置文件

#master配置文件
#保证PID文件区分，PID文件主要用于保证守护进程单例运行
pidfile /var/run/redis-master.pid
#区分LOG文件
logfile "/data/redis/6379/log/redis.log"
#区分持久化文件
dir /data/redis/6379/data
#区分端口
port 6379

#slave配置文件
pidfile /var/run/redis-slave.pid
logfile "/data/redis/6380/log/redis.log"
dir /data/redis/6380/data
port 6380
slaveof 127.0.0.1 6379
#如果为yes,slave实例只读,如果为no,slave实例可读可写。默认
slave-read-only yes

3、启动

redis-server /etc/redis/redis-master.conf
redis-server /etc/redis/redis-slave.conf

4、验证 master启动日志

[root@localhost redis]# cat /data/redis/6379/log/redis.log
[24787] 13 Sep 10:39:45.143 * Max number of open files set to 10032
[24787] 13 Sep 10:39:45.145 # Warning: 32 bit instance detected but no memory limit set. Setting 3 GB maxmemory limit with 'noeviction' policy now.
_._
_.-``__ ''-._
_.-``    `.  `_.  ''-._           Redis 2.8.7 (00000000/0) 32 bit
.-`` .-```.  ```\/    _.,_ ''-._
(    '      ,       .-`  | `,    )     Running in stand alone mode
|`-._`-...-` __...-.``-._|'` _.-'|     Port: 6379
|    `-._   `._    /     _.-'    |     PID: 24787
`-._    `-._  `-./  _.-'    _.-'
|`-._`-._    `-.__.-'    _.-'_.-'|
|    `-._`-._        _.-'_.-'    |           http://redis.io
`-._    `-._`-.__.-'_.-'    _.-'
|`-._`-._    `-.__.-'    _.-'_.-'|
|    `-._`-._        _.-'_.-'    |
`-._    `-._`-.__.-'_.-'    _.-'
`-._    `-.__.-'    _.-'
`-._        _.-'
`-.__.-'
[24787] 13 Sep 10:39:45.146 # Server started, Redis version 2.8.7
[24787] 13 Sep 10:39:45.146 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
[24787] 13 Sep 10:39:45.146 * The server is now ready to accept connections on port 6379
[24787] 13 Sep 10:40:54.342 * DB saved on disk
[24787] 13 Sep 10:42:50.581 * Slave asks for synchronization
[24787] 13 Sep 10:42:50.581 * Full resync requested by slave.
[24787] 13 Sep 10:42:50.581 * Starting BGSAVE for SYNC
[24787] 13 Sep 10:42:50.582 * Background saving started by pid 24816
[24816] 13 Sep 10:42:50.586 * DB saved on disk
[24816] 13 Sep 10:42:50.587 * RDB: 0 MB of memory used by copy-on-write
[24787] 13 Sep 10:42:50.673 * Background saving terminated with success
[24787] 13 Sep 10:42:50.673 * Synchronization with slave succeeded
[24787] 13 Sep 10:47:04.093 * DB saved on disk

slave 启动日志

[root@localhost redis]# cat /data/redis/6380/log/redis.log
[24813] 13 Sep 10:42:50.578 * Max number of open files set to 10032
[24813] 13 Sep 10:42:50.579 # Warning: 32 bit instance detected but no memory limit set. Setting 3 GB maxmemory limit with 'noeviction' policy now.
_._
_.-``__ ''-._
_.-``    `.  `_.  ''-._           Redis 2.8.7 (00000000/0) 32 bit
.-`` .-```.  ```\/    _.,_ ''-._
(    '      ,       .-`  | `,    )     Running in stand alone mode
|`-._`-...-` __...-.``-._|'` _.-'|     Port: 6380
|    `-._   `._    /     _.-'    |     PID: 24813
`-._    `-._  `-./  _.-'    _.-'
|`-._`-._    `-.__.-'    _.-'_.-'|
|    `-._`-._        _.-'_.-'    |           http://redis.io
`-._    `-._`-.__.-'_.-'    _.-'
|`-._`-._    `-.__.-'    _.-'_.-'|
|    `-._`-._        _.-'_.-'    |
`-._    `-._`-.__.-'_.-'    _.-'
`-._    `-.__.-'    _.-'
`-._        _.-'
`-.__.-'
[24813] 13 Sep 10:42:50.580 # Server started, Redis version 2.8.7
[24813] 13 Sep 10:42:50.580 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
[24813] 13 Sep 10:42:50.580 * The server is now ready to accept connections on port 6380
[24813] 13 Sep 10:42:50.580 * Connecting to MASTER 127.0.0.1:6379
[24813] 13 Sep 10:42:50.580 * MASTER <-> SLAVE sync started
[24813] 13 Sep 10:42:50.580 * Non blocking connect for SYNC fired the event.
[24813] 13 Sep 10:42:50.581 * Master replied to PING, replication can continue...
[24813] 13 Sep 10:42:50.581 * Partial resynchronization not possible (no cached master)
[24813] 13 Sep 10:42:50.583 * Full resync from master: 9ef3d846e366f7643db9e9250b508d64a34c1079:1
[24813] 13 Sep 10:42:50.673 * MASTER <-> SLAVE sync: receiving 31 bytes from master
[24813] 13 Sep 10:42:50.673 * MASTER <-> SLAVE sync: Flushing old data
[24813] 13 Sep 10:42:50.673 * MASTER <-> SLAVE sync: Loading DB in memory
[24813] 13 Sep 10:42:50.674 * MASTER <-> SLAVE sync: Finished with success
[24813] 13 Sep 10:47:04.096 * DB saved on disk

数据同步验证：

[root@localhost redis]# redis-cli
127.0.0.1:6379> set name test
OK
127.0.0.1:6379> save
OK

[root@localhost redis]# redis-cli -p 6380
127.0.0.1:6380> keys *
1) "name"

在 redis 从机redis上的config 文件里色织slavof ip port;
就ok了，开启他就寻找主机自动同步，很快，比使用java等要高效 。这是他的机制，不需要额外方法
 

结构不同
先讲MySQL，MySQL中一个事务提交之后就永久写入了，同时将事务的操作写入日志。然后，slave从master中请求日志，复制这个事务的操作（注意不是sql语句）。
而Redis的主从同步和数据快照有关，Redis定期将内存中数据作快照保存在文件中，mater只要将文件发送给slave更新就可以了。
MySQL的slave需要请求从从某个事务（就是slave刚完成的那个）开始的所有日志，而redis不需要，slave只要将收到的快照排队，一个一个复制到硬盘、内存就行了。