简介：
使用magent架设memcached高可用，当主的挂掉以后，备机可以继续使用。
magent
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memcached1 memcached2 memcached3
（master) (master) (backup)
一 安装memcached
下载下面安装包
libevent-2.0.21-stable.tar.gz
memcached-1.4.32.tar.gz
magent-0.5.tar.gz
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安装libevent
| tar –xzvf libevent-2.0.21-stable.tar.gz cd libevent-2.0.21-stable ./configure –prefix=/usr/local/libevent make make install
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安装memcached
| tar –xzvf memcached-1.4.32 cd memcached-1.4.32 ./configure --prefix=/opt/memcached --with-libevent=/usr/local/libevent/ make make install
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magent安装
下载安装包文件magent-0.5.tar.gz
解压tar –xzvf magent-0.5.tar.gz
make #执行编译安装
把编译好的magent拷贝到/opt/memcached/bin/ 目录下
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安装报错解决方案
| [root@i-0boypofz magent]# make gcc -Wall -g -O2 -I/usr/local/include -m64 -c -o magent.o magent.c magent.c:71:19: error: event.h: No such file or directory magent.c:130: error: field ‘ev’ has incomplete type magent.c:161: error: field ‘ev’ has incomplete type magent.c: In function ‘server_free’: magent.c:494: warning: implicit declaration of function ‘event_del’ magent.c: In function ‘pool_server_handler’: magent.c:514: error: ‘EV_READ’ undeclared (first use in this function) magent.c:514: error: (Each undeclared identifier is reported only once
# 解决办法，检查下libevent安装路径，如果自定义安装了，拷贝下路径库。 ln -s /usr/lib/libevent* /usr/lib64/
[root@i-0boypofz magent]# make gcc -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
解决方法： vi ./ketama.h #在开头加入 #ifndef SSIZE_MAX #define SSIZE_MAX 32767 #endif
#libm.a不存在的时候，需要拷贝下面so，如果没有，需要安装glibc glibc-devel cp /usr/lib64/libm.so /usr/lib64/libm.a
gcc -Wall -g -O2 -I/usr/local/include -m64 -o magent magent.o ketama.o /usr/lib64/libevent.a /usr/lib64/libm.a /usr/lib64/libevent.a(event.o): In function `gettime': /root/libevent-2.0.21-stable/event.c:370: undefined reference to `clock_gettime' /usr/lib64/libevent.a(event.o): In function `detect_monotonic': /root/libevent-2.0.21-stable/event.c:340: undefined reference to `clock_gettime' collect2: ld returned 1 exit status make: *** [magent] Error 1
解决方法：
vi Makefile CFLAGS = -Wall -g -O2 -I/usr/local/include $(M64) 改为： CFLAGS = -lrt -Wall -g -O2 -I/usr/local/include $(M64)
[root@i-0boypofz magent5]# make gcc -lrt -Wall -g -O2 -I/usr/local/include -o magent magent.o ketama.o -levent ketama.o: In function `create_ketama': /root/magent5/ketama.c:399: undefined reference to `floorf' collect2: ld returned 1 exit status make: *** [magent] Error 1
解决办法： vi Makefile
LIBS = -levent –lm
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三 启动
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启动memcached
| /opt/memcached/bin/memcached -d -u root -c 10000 -m 8192 192.168.100.22 -p 11211
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启动magent
| /opt/memcached/bin/magent -u root -n 102400 -l 192.168.100.24 -p 12001 -s 192.168.100.22:192.168.100.23:11211 -b 192.168.100.24:11211 |
四 测试
4.1 模拟一台主的坏掉
设置数据：
kill掉一台主
验证数据正常：
4.2 模拟第二台主机也down
验证数据，读写都正常。
4.3 模拟三台都宕机
magent无法读取数据
4.4 模拟主机down掉一台，启动主机，查看数据是否丢失
测试检查丢失了一条数据。
所以当主down以后，不要立即启动主，需要非工作时间处理。
本文转自 woshiwei201 51CTO博客，原文链接:http://blog.51cto.com/chenwei/1869124
