Memcached HA架构探索
https://code.google.com/p/memagent/
标签：memcached magent 高可用 HA 架构
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magent是一款开源的Memcached代理服务器软件，可以用它做一些高可用架构尝试。目前magent已更新到0.6，我在centos 6.0 64bit机器上面未编译通过，所以我在这里用0.5的源码来测试;
google项目地址：http://code.google.com/p/memagent/
一、安装步骤：
1、编译安装libevent：
- wget https://github.com/downloads/lib ... .0.16-stable.tar.gz
- tar zxvf libevent-2.0.16-stable.tar.gz
- cd libevent-2.0.16-stable/
- ./configure --prefix=/usr
- make && make install
- cd ../
2、编译安装Memcached：
- wget http://memcached.googlecode.com/files/memcached-1.4.14.tar.gz
- tar zxvf memcached-1.4.14.tar.gz
- cd memcached-1.4.14/
- ./configure --prefix=/usr --with-libevent=/usr
- make && make install
- cd ../
3、编译安装magent：
- mkdir magent
- cd magent/
- wget http://memagent.googlecode.com/files/magent-0.5.tar.gz
- tar zxvf magent-0.5.tar.gz
- /sbin/ldconfig
- vim Makefile
- CFLAGS = -Wall -O2 -g
- 改为：
- CFLAGS = -lrt -Wall -O2 -g
- sed -i "s#LIBS = -levent#LIBS = -levent -lm#g" Makefile
- vim ketama.h
- 加入
- #ifndef SSIZE_MAX
- #define SSIZE_MAX 32767
- #endif
- make
- cp magent /usr/bin/magent
- cd ../
安装中常遇到的问题
- gcc -lrt -Wall -g -O2 -I/usr/local/include -m64 -c -o magent.o magent.c
- magent.c: In function ‘writev_list’:
- magent.c:729: error: ‘SSIZE_MAX’ undeclared (first use in this function)
- magent.c:729: error: (Each undeclared identifier is reported only once
- magent.c:729: error: for each function it appears in.)
- make: *** [magent.o] Error 1
解决办法：
- vim ketama.h
- 加入
- #ifndef SSIZE_MAX
- #define SSIZE_MAX 32767
- #endif
二、高可用网络架构
此架构生产环境需要负载均衡器做负载，具体使用什么软件或硬件就要看你的具体情况来定了。
生产环境每台服务器分别启动一个memcached进程和magen进程做冗余
- memcached -d -m 256 -l 192.168.10.11 -p 11211 -u www -c 10240 -P /tmp/memcached.pid -vv >/home/logs/memcached.txt 2>&1
- memcached -d -m 128 -l 192.168.10.12 -p 11211 -u www -c 10240 -P /tmp/memcached.pid -vv >/home/logs/memcached.txt 2>&1
- memcached -d -m 128 -l 192.168.10.13 -p 11211 -u www -c 10240 -P /tmp/memcached.pid -vv >/home/logs/memcached.txt 2>&1
- magent -u www -n 51200 -l 192.168.10.11 -p 12000 -s 192.168.10.12:11211 -s 192.168.10.13:11211 -b 192.168.10.11:11211
- magent -u www -n 51200 -l 192.168.10.12 -p 12000 -s 192.168.10.12:11211 -s 192.168.10.13:11211 -b 192.168.10.11:11211
- magent -u www -n 51200 -l 192.168.10.13 -p 12000 -s 192.168.10.12:11211 -s 192.168.10.13:11211 -b 192.168.10.11:11211
参数说明：
-s 为要写入的memcached，
-b 为备份用的memcached。
说明：测试环境用magent和memached的不同端口来实现，在生产环境中可以将magent和memached作为一组放到多台服务器上。
看到了吧这样的架构最好做负载了，用一个VIP分别映射三台magent的12000端口即可。
#实验环境测试过程：
- [root@odb ~]# telnet 127.0.0.1 12000
- Trying 127.0.0.1…
- Connected to localhost.localdomain (127.0.0.1).
- Escape character is ‘^]’.
- set key 0 0 8 <—在10000端口设置key的值
- 88888888
- STORED
- quit
- Connection closed by foreign hos
- [root@odb ~]# telnet 127.0.0.1 11211
- Trying 127.0.0.1…
- Connected to localhost.localdomain (127.0.0.1).
- Escape character is ‘^]’.
- get key <—在11211端口获取key的值成功
- VALUE key 0 8
- 88888888
- END
- quit
- Connection closed by foreign host.
- [root@odb ~]# telnet 127.0.0.1 11211
- Trying 127.0.0.1…
- Connected to localhost.localdomain (127.0.0.1).
- Escape character is ‘^]’.
- get key <—在11211端口获取key的值成功
- VALUE key 0 8
- 88888888
- END
- quit
- Connection closed by foreign host.
- 高可用性测试：
- [root@odb ~]# ps aux |grep -v grep |grep memcached
- root 23455 0.0 0.0 5012 1796 ? Ss 09:22 0:00 memcached -m 1 -u root -d -l 127.0.0.1 -p 11212
- root 24950 0.0 0.0 4120 1800 ? Ss 10:58 0:00 memcached -m 1 -u root -d -l 127.0.0.1 -p 11211
- [root@odb ~]# ps aux |grep -v grep |grep ‘magent -u’
- root 25919 0.0 0.0 2176 484 ? Ss 12:00 0:00 magent -u root -n 51200 -l 127.0.0.1 -p 10000 -s 127.0.0.1:11211 -b 127.0.0.1:11212
- root 25925 0.0 0.0 3004 484 ? Ss 12:00 0:00 magent -u root -n 51200 -l 127.0.0.1 -p 11000 -s 127.0.0.1:11212 -b 127.0.0.1:11211
- [root@odb ~]# telnet 127.0.0.1 10000
- Trying 127.0.0.1…
- Connected to localhost.localdomain (127.0.0.1).
- Escape character is ‘^]’.
- set stone 0 0 6 <—在10000端口设置stone的值
- 123456
- STORED
- quit
- Connection closed by foreign host.
- [root@odb ~]# telnet 127.0.0.1 11000
- Trying 127.0.0.1…
- Connected to localhost.localdomain (127.0.0.1).
- Escape character is ‘^]’.
- set shidl 0 0 6 <—在11000端口设置shidl的值
- 666666
- STORED
- get stone <—在11000端口获取stone的值成功
- VALUE stone 0 6
- 123456
- END
- incr stone 2 <—在11000端口修改stone的值成功
- 123458
- get stone
- VALUE stone 0 6 <—在11000端口验证stone的值，证明上面的修改成功
- 123458
- END
- get shidl <—在11000端口获取shidl的值成功
- VALUE shidl 0 6
- 666666
- END
- quit <—退出11000端口
- Connection closed by foreign host.
- [root@odb ~]# telnet 127.0.0.1 10000
- Trying 127.0.0.1…
- Connected to localhost.localdomain (127.0.0.1).
- Escape character is ‘^]’.
- get stone <—在10000端口获取stone的值，已被修改
- VALUE stone 0 6
- 123458
- END
- get shidl <—在10000端口获取shidl的值成功
- VALUE shidl 0 6
- 666666
- END
- delete shidl <—在10000端口删除shidl
- DELETED
- get shidl <—在10000端口删除shidl生效
- END
- quit
- Connection closed by foreign host.
- [root@odb ~]# telnet 127.0.0.1 11000
- Trying 127.0.0.1…
- Connected to localhost.localdomain (127.0.0.1).
- Escape character is ‘^]’.
- get shidl <—在11000端口验证删除shidl生效
- END
- get stone <—在11000端口获取stone的值成功
- VALUE stone 0 6
- 123458
- END
- quit
- Connection closed by foreign host.
Down机模拟测试：
Down掉11211端口的memcached：
- [root@odb ~]# kill -9 24950
- [root@odb ~]# telnet 127.0.0.1 10000
- Trying 127.0.0.1…
- Connected to localhost.localdomain (127.0.0.1).
- Escape character is ‘^]’.
- get stone <—在10000依然可以获取stone的值
- VALUE stone 0 6
- 123458
- END
- quit
- Connection closed by foreign host.
- [root@odb ~]# telnet 127.0.0.1 11000
- Trying 127.0.0.1…
- Connected to localhost.localdomain (127.0.0.1).
- Escape character is ‘^]’.
- get stone <—在11000依然可以获取stone的值
- VALUE stone 0 6
- 123458
- END
- quit
- Connection closed by foreign host.
- Down掉11000端口的magent：
- [root@odb ~]# kill -9 25925
- [root@odb ~]# telnet 127.0.0.1 10000
- Trying 127.0.0.1…
- Connected to localhost.localdomain (127.0.0.1).
- Escape character is ‘^]’.
- get stone <—在10000依然可以获取stone的值
- VALUE stone 0 6
- 123458
- END
- quit
- Connection closed by foreign host.
本文出自 “Centi.Linux” 博客，请务必保留此出处http://centilinux.blog.51cto.com/1454781/968104
