Memcached 高可用方案 Repcached

Repcached說明
    Repcached是一個單master單 slave的方案，但它的 master/slave都是可讀寫的，而且可以相互同步。如果 master down掉， slave偵測到連接斷了，它會自動 listen而成為 master；而如果 slave壞掉， master也會偵測到連接斷，它就會重新 listen等待新的 slave加入。 

Repcached 安裝：
1：安裝條件（root用戶執行）

apt-get install libevent-dev

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

2：解壓&進入目錄編譯

root@m2:~/nosql# tar zxvf memcached-1.2.8-repcached-2.2.tar.gz

cd memcached-1.2.8-repcached-2.2/

./configure --enable-replication --program-transform-name=s/memcached/repcached/

make&&make install 

注意：make的時候報錯

memcached.c: 在函數‘add_iov’中:
memcached.c:696:30: 錯誤： ‘IOV_MAX’未聲明(在此函數內第一次使用)
memcached.c:696:30: 附注： 每個未聲明的標識符在其出現的函數內只報告一次
make[2]: *** [memcached-memcached.o] 錯誤 1

需要修改 memcached.c 文件：

/* FreeBSD 4.x doesn't have IOV_MAX exposed. */
#ifndef IOV_MAX
#if defined(__FreeBSD__) || defined(__APPLE__)
# define IOV_MAX 1024
#endif
#endif 改成： /* FreeBSD 4.x doesn't have IOV_MAX exposed. */
#ifndef IOV_MAX
# define IOV_MAX 1024
#endif

再make&&make install，編譯之后退出root用戶。

開啟repcached：

啟動master：[必須是11211端口]

1：
zhoujy@m2:~$ repcached -d -m 64 -p 11211 -u nobody -l 127.0.0.1 -v
zhoujy@m2:~$ replication: listen
或則：
2：
zhoujy@m2:~$ repcached -d -m 64 -p 11211 -u nobody -l 127.0.0.1 -x 127.0.0.1 -X 11111 -v    #（11211：master端口；11111：同步端口）
zhoujy@m2:~$ replication: connect (peer=127.0.0.1:11111)
replication: marugoto copying
replication: close
replication: listen

啟動slave： -x：同行memcached的地址。

1：
zhoujy@m2:~$ repcached -d -m 64 -p 11212 -u nobody -l 127.0.0.1 -x 127.0.0.1  -v
zhoujy@m2:~$ replication: connect (peer=127.0.0.1:11212)
replication: marugoto copying
或則：
2：
zhoujy@m2:~$ repcached -d -m 64 -p 11212 -u nobody -l 127.0.0.1 -x 127.0.0.1 -X 11111 -v   #（11212：slave端口；11111：同步端口）
zhoujy@m2:~$ replication: connect (peer=127.0.0.1:11111)
replication: marugoto copying
replication: accept
replication: start

復制：11211的數據復制到11212中

zhoujy@m2:~$ telnet 127.0.0.1 11211
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
set a 0 0 3
abc
STORED
set aa 0 0 5
abcde
STORED
quit
Connection closed by foreign host.

zhoujy@m2:~$ telnet 127.0.0.1 11212
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
get a
VALUE a 0 3
abc
END
get aa
VALUE aa 0 5
abcde
END

反復制：11212 同步到了11211

set b 0 0 3
ABC
STORED
set bb 0 0 5
ABCDE
STORED

quit
Connection closed by foreign host.
zhoujy@m2:~$ telnet 127.0.0.1 11211
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
get b
VALUE b 0 3
ABC
END
get bb
VALUE bb 0 5
ABCDE
END

主從相互刪除等操作都相互影響：

zhoujy@m2:~$ telnet 127.0.0.1 11211
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
delete aa
DELETED
delete bb
DELETED
quit
Connection closed by foreign host.
zhoujy@m2:~$ telnet 127.0.0.1 11212
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
get aa
END
get bb
END
delete a
DELETED
get a
END
quit
Connection closed by foreign host.
zhoujy@m2:~$ telnet 127.0.0.1 11211
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
get a
END
get b
VALUE b 0 3
ABC
END

至此，上面的同步已經完成。

優點：
數據冗余
兩台memcached都可以進行讀寫操作

缺點：
只支持單對單
只支持memcached 1.2.x版本

 

擴展：

http://houwenhui.gotoip2.com/archives/1384