memcached单点

一．Repcached （memcached同步补丁）

下载地址：http://sourceforge.net/projects/repcached/files/repcached/2.2.1-1.2.8/

版本号：memcached 1.2.8  repcached 2.2.1

1、repcached介绍

repcached是日本人开发的实现memcached复制功能，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坏掉， 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

2、安装

在两台服务器上分别安装memcached服务，另注本文libevent的版本为：libevent-1.4.13，下载地址: http://www.monkey.org/~provos/libevent-1.4.13-stable.tar.gz （安装省略）

repcached有两种方式：

方式一、下载对应的repcached版本

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1.#wget http://downloads.sourceforge.net/repcached/memcached-1.2.8-repcached-2.2.tar.gz

2.#tar zxf memcached-1.2.8-repcached-2.2.tar.gz

3.#cd memcached-1.2.8-repcached-2.2

方式二、下载对应patch版本

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1.#wget http://downloads.sourceforge.net/repcached/repcached-2.2-1.2.8.patch.gz

2.#gzip -cd ../repcached-2.2-1.2.8.patch.gz | patch -p1】

3.#./configure –enable-replication

4.# make

5.# make install

3、启动：

启动master

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1.# ./memcached -v -u root -d -l 127.0.0.1 -p 11211 -x 127.0.0.1 -X 11111   （11211：master端口；11111：同步端口）

2.replication: connect (peer=127.0.0.1:11111)

3.replication: accept

4.replication: marugoto copying

5.replication: start

启动salve

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1.# ./memcached -v -u root -d -l 127.0.0.1 -p 11212 -x 127.0.0.1 -X 11111   （11212：slave端口；11111：同步端口）

2.replication: connect (peer=127.0.0.1:11111)

3.replication: marugoto copying

4.replication: close

5.replication: listen

4、测试：

操作master

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01.[root@localhost bin]# telnet 127.1 11211

02.Trying 127.0.0.1...

03.Connected to localhost.localdomain (127.0.0.1)...

04.Escape character is '^]'.

05.get key1

06.END

07.set key1 0 0 2

08.aa

09.STORED

10.quit

11.Connection closed by foreign host.

查看slave

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01.[root@localhost bin]# telnet 127.1 11212

02.Trying 127.0.0.1...

03.Connected to localhost.localdomain (127.0.0.1)...

04.Escape character is '^]'.

05.get key1

06.VALUE key1 0 2

07.aa

08.END

09.quit

10.Connection closed by foreign host.

注意：如果master down机，slave接管并成为master，这时down机的master只能启用slave,他们之间互换角色，才能保持复制功能。换句话说，master没有抢占功能。而且，同步间隔时间未知。

优点：

1. 数据冗余
2. 两台memcached都可以进行读写操作

缺点：

1. 只支持单对单
2. 只支持memcached 1.2.x版本

二．Magent （memcached的代理）

原文地址：http://blog.s135.com/post/393/

magent是一款开源的Memcached代理服务器软件，其项目网址为：

http://code.google.com/p/memagent/

1、安装步骤：

a、编译安装libevent：

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1.wget http://monkey.org/~provos/libevent-1.4.9-stable.tar.gz

2.tar zxvf libevent-1.4.9-stable.tar.gz

3.cd libevent-1.4.9-stable/

4../configure --prefix=/usr

5.make && make install

6.cd ../

b、编译安装Memcached：

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1.wget http://danga.com/memcached/dist/memcached-1.2.6.tar.gz

2.tar zxvf memcached-1.2.6.tar.gz

3.cd memcached-1.2.6/

4../configure --with-libevent=/usr

5.make && make install

6.cd ../

c、编译安装magent：

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01.mkdir magent

02.cd magent/

03.wget http://memagent.googlecode.com/files/magent-0.5.tar.gz

04.tar zxvf magent-0.5.tar.gz

05./sbin/ldconfig

06.sed -i "s#LIBS = -levent#LIBS = -levent -lm#g" Makefile

07.make

08.cp magent /usr/bin/magent

09.cd ../

2、使用实例：

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1.memcached -m 1 -u root -d -l 127.0.0.1 -p 11211

2.memcached -m 1 -u root -d -l 127.0.0.1 -p 11212

3.memcached -m 1 -u root -d -l 127.0.0.1 -p 11213

4.magent -u root -n 51200 -l 127.0.0.1 -p 12000 -s 127.0.0.1:11211 -s 127.0.0.1:11212 -b 127.0.0.1:11213

1. 分别在11211、11212、11213端口启动3个Memcached进程，在12000端口开启magent代理程序；
2. 11211、11212端口为主Memcached，11213端口为备份Memcached；
3. 连接上12000的magent，set key1和set key2，根据哈希算法，key1被写入11212和11213端口的Memcached，key2被写入11212和11213端口的Memcached；
4. 当11211、11212端口的Memcached死掉，连接到12000端口的magent取数据，数据会从11213端口的Memcached取出；
5. 当11211、11212端口的Memcached重启复活，连接到12000端口，magent会从11211或11212端口的Memcached取数据，由于这两台Memcached重启后无数据，因此magent取得的将是空值，尽管11213端口的Memcached还有数据（此问题尚待改进）。

3、整个测试流程：

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01.[root@centos52 ~]# telnet 127.0.0.1 12000

02.Trying 127.0.0.1...

03.Connected to 127.0.0.1.

04.Escape character is '^]'.

05.stats

06.memcached agent v0.4

07.matrix 1 -> 127.0.0.1:11211, pool size 0

08.matrix 2 -> 127.0.0.1:11212, pool size 0

09.END

10.set key1 0 0 8

11.zhangyan

12.STORED

13.set key2 0 0 8

14.zhangyan

15.STORED

16.quit

17.Connection closed by foreign host.

18. 

19.[root@centos52 ~]# telnet 127.0.0.1 11211

20.Trying 127.0.0.1...

21.Connected to 127.0.0.1.

22.Escape character is '^]'.

23.get key1

24.END

25.get key2

26.VALUE key2 0 8

27.zhangyan

28.END

29.quit

30.Connection closed by foreign host.

31. 

32.[root@centos52 ~]# telnet 127.0.0.1 11212

33.Trying 127.0.0.1...

34.Connected to 127.0.0.1.

35.Escape character is '^]'.

36.get key1

37.VALUE key1 0 8

38.zhangyan

39.END

40.get key2

41.END

42.quit

43.Connection closed by foreign host.

44. 

45.[root@centos52 ~]# telnet 127.0.0.1 11213

46.Trying 127.0.0.1...

47.Connected to 127.0.0.1.

48.Escape character is '^]'.

49.get key1

50.VALUE key1 0 8

51.zhangyan

52.END

53.get key2

54.VALUE key2 0 8

55.zhangyan

56.END

57.quit

58.Connection closed by foreign host.

模拟11211、11212端口的Memcached死掉

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01.[root@centos52 ~]# ps -ef | grep memcached

02.root      6589     1  0 01:25 ?        00:00:00 memcached -m 1 -u root -d -l 127.0.0.1 -p 11211

03.root      6591     1  0 01:25 ?        00:00:00 memcached -m 1 -u root -d -l 127.0.0.1 -p 11212

04.root      6593     1  0 01:25 ?        00:00:00 memcached -m 1 -u root -d -l 127.0.0.1 -p 11213

05.root      6609  6509  0 01:44 pts/0    00:00:00 grep memcached

06.[root@centos52 ~]# kill -9 6589

07.[root@centos52 ~]# kill -9 6591

08.[root@centos52 ~]# telnet 127.0.0.1 12000

09.Trying 127.0.0.1...

10.Connected to 127.0.0.1.

11.Escape character is '^]'.

12.get key1

13.VALUE key1 0 8

14.zhangyan

15.END

16.get key2

17.VALUE key2 0 8

18.zhangyan

19.END

20.quit

21.Connection closed by foreign host.

模拟11211、11212端口的Memcached重启复活

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01.[root@centos52 ~]# memcached -m 1 -u root -d -l 127.0.0.1 -p 11211

02.[root@centos52 ~]# memcached -m 1 -u root -d -l 127.0.0.1 -p 11212

03.[root@centos52 ~]# telnet 127.0.0.1 12000

04.Trying 127.0.0.1...

05.Connected to 127.0.0.1.

06.Escape character is '^]'.

07.get key1

08.END

09.get key2

10.END

11.quit

12.Connection closed by foreign host.

优点：

1. 可以做多主或多从

缺点：

1. 当master宕掉又恢复后，取不到数据。