Memcached学习笔记（四）——repcached高可用方案
repcached：全称 replication cached是由日本人发明的memcached的高可用性技术，简称复制缓冲区技术。
使用场景：它是一个单master单 slave的方案，但它的 master/slave都是可读写的，而且可以相互同步，如果 master 宕机， slave侦测到连接断了，它会自动
listen而成为 master；而如果 slave坏掉， master也会侦测到连接断，它就会重新 listen等待新的 slave加入。
（一）安装相关依赖（编译repcached程序所依赖的包）：
[root@localhost memcached-1.2.8-repcached-2.2]# yum install libevent-devel
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* addons: mirrors.yun-idc.com
* base: mirrors.yun-idc.com
* epel: mirrors.yun-idc.com
* extras: mirrors.yun-idc.com
* updates: mirrors.yun-idc.com
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package libevent-devel.i386 0:1.4.13-1 set to be updated
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
libevent-devel i386 1.4.13-1 base 373 k
Transaction Summary
================================================================================
Install 1 Package(s)
Upgrade 0 Package(s)
Total download size: 373 k
Is this ok [y/N]: y
Downloading Packages:
libevent-devel-1.4.13-1.i386.rpm | 373 kB 00:04
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
Installing : libevent-devel 1/1
Installed:
libevent-devel.i386 0:1.4.13-1
Complete!
[root@localhost memcached-1.2.8-repcached-2.2]#
（二）下载并安装：memcached-1.2.8-repcached-2.2.tar.gz
[root@localhost ~]# wget http://downloads.sourceforge.net/repcached/memcached-1.2.8-repcached-2.2.tar.gz
--2013-03-23 13:35:56-- http://downloads.sourceforge.net/repcached/memcached-1.2.8-repcached-2.2.tar.gz
Resolving downloads.sourceforge.net... 216.34.181.59
Connecting to downloads.sourceforge.net|216.34.181.59|:80... connected.
HTTP request sent, awaiting response... 301 Moved Permanently
Location: http://downloads.sourceforge.net/project/repcached/repcached/2.2-1.2.8/memcached-1.2.8-repcached-2.2.tar.gz [following]
--2013-03-23 13:35:57-- http://downloads.sourceforge.net/project/repcached/repcached/2.2-1.2.8/memcached-1.2.8-repcached-2.2.tar.gz
Reusing existing connection to downloads.sourceforge.net:80.
HTTP request sent, awaiting response... 302 Found
Location: http://nchc.dl.sourceforge.net/project/repcached/repcached/2.2-1.2.8/memcached-1.2.8-repcached-2.2.tar.gz [following]
--2013-03-23 13:35:59-- http://nchc.dl.sourceforge.net/project/repcached/repcached/2.2-1.2.8/memcached-1.2.8-repcached-2.2.tar.gz
Resolving nchc.dl.sourceforge.net... 211.79.60.17, 2001:e10:ffff:1f02::17
Connecting to nchc.dl.sourceforge.net|211.79.60.17|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 227510 (222K) [application/x-gzip]
Saving to: `memcached-1.2.8-repcached-2.2.tar.gz'
100%[======================================>] 227,510 240K/s in 0.9s
2013-03-23 13:36:01 (240 KB/s) - `memcached-1.2.8-repcached-2.2.tar.gz' saved [227510/227510]
[root@localhost ~]# tar zxvf memcached-1.2.8-repcached-2.2.tar.gz
[root@localhost ~]# ./configure --enable-replication --program-transform-name=s/memcached/repcached/
（三）启动repcached （用非root操作）：
[hadoop@localhost ~]$ /usr/local/bin/repcached -p 11211 -v -d
replication: listen
[hadoop@localhost ~]$ /usr/local/bin/repcached -p 11212 -x localhost -v -d
replication: connect (peer=127.0.0.1:11212)
replication: marugoto copying
replication: accept
[hadoop@localhost ~]$ replication: start
参数解释：
-d ： 后台运行memcached进程
-p ： 默认监听端口11211 11212
-x ： 监听高可用机器，如果是监听默认端口不用写端口号，localhost就是监听本机
作用：第二个repcached监听第一个repcached如果有问题就接管
（四）复制实验：
先连接11211机器，设置name 值为“zhangsan”
[hadoop@localhost ~]$ telnet localhost 11211
Trying 127.0.0.1...
Connected to localhost (127.0.0.1).
Escape character is '^]'.
set name 0 0 8
zhangsan
STORED
get name
VALUE name 0 8
zhangsan
END
quit
Connection closed by foreign host.
连接11212机器，读取name值：
[hadoop@localhost ~]$ telnet localhost 11212
Trying 127.0.0.1...
Connected to localhost (127.0.0.1).
Escape character is '^]'.
get name
VALUE name 0 8
zhangsan
END
（五）反向复制实验
连接11211，设置age值为23
[hadoop@localhost ~]$ telnet localhost 11212
Trying 127.0.0.1...
Connected to localhost (127.0.0.1).
Escape character is '^]'.
get name
VALUE name 0 8
zhangsan
END
set age 0 0 2
23
STORED
get age
VALUE age 0 2
23
END
连接11211，读取age值：
[hadoop@localhost ~]$ telnet localhost 11211
Trying 127.0.0.1...
Connected to localhost (127.0.0.1).
Escape character is '^]'.
get age
VALUE age 0 2
23
END
get name
VALUE name 0 8
zhangsan
END
quit
Connection closed by foreign host.
（六）监控memcached:
[hadoop@localhost ~]$ stats cachedump 1 10
-bash: stats: command not found
[hadoop@localhost ~]$ telnet localhost 11211
Trying 127.0.0.1...
Connected to localhost (127.0.0.1).
Escape character is '^]'.
stats cachedump 1 10
ITEM name [8 b; 1365421489 s]
ITEM age [2 b; 1365421489 s]
END
stats items
STAT items:1:number 2
STAT items:1:age 119
STAT items:1:evicted 0
STAT items:1:evicted_time 0
STAT items:1:outofmemory 0
STAT items:1:tailrepairs 0
END
（7）实验完成，祝您成功！