Memcached的特点:

1.在Memcached中可以保存的item数据量是没有限制的,只要内存足够;
2.Memcached单进程最大使用内存为2GB,要使用更多内存,可以分别在不同端口启动多个Memcached进程;
3.Memcached是一种无阻塞的socket通信方式的服务,基于libevent库,由于无阻塞通信,对内存读写速度非常之快;
4.Memcached分为服务器和客户端,可以配置多个服务器和客户端,应用于分布式的服务非常广泛;
5.Memcached作为小规模的数据分布式平台是非常高效的;

服务器 IP地址 软件包
主Memcached 192.168.5.129 libevent-2.1.8-stable.tar.gz、memcached-1.5.9.tar.gz、magent-0.5.tar.gz、keepalived
从Memcached 192.168.5.139 libevent-2.1.8-stable.tar.gz、memcached-1.5.9.tar.gz、magent-0.5.tar.gz、keepalived
Client 192.168.5.141 telnet

搭建Memcached服务器

Memcached服务器在两台服务器上都需要搭建,方式完全相同,在安装memcached服务器是需先安装libevent,然后再安装memcached。

安装环境包

yum -y install gcc gcc-c++ make

编译安装libevent(必须先安装)

#解压
tar zxvf libevent-2.1.8-stable.tar.gz -C /opt

#切换到libevent目录
cd /opt/libevent-2.1.8-stable/

#配置
./configure --prefix=/usr/

#编译及安装
make && make install

编译安装memcached

#解压
tar zxvf memcached-1.5.9.tar.gz -C /opt/

#切换到memcached
cd /opt/memcached-1.5.9/

#配置(指定libevent路径)
./configure --with-libevent=/usr/

#编译及安装
make && make install

优化启动(支持复制功能的Mencached需要安装后的libevent-2.1.so.6模块,不然启动服务会报错)

ln -s /usr/lib/libevent-2.1.so.6 /usr/lib64/libevent-2.1.so.6

在主服务器上安装magent

magent是一个memcached代理软件,防止单点故障,缓存代理也可以着备份,通过客户端连接缓存代理服务器,缓存代理服务器连接缓存服务器。

#创建magent目录

mkdir /opt/magent

#解压

tar zxvf magent-0.5.tar.gz -C /opt/magent

#切换到目录

cd /opt/magent

#让动态链接库为系统所共享

/sbin/ldconfig

#编辑ketama.h,添加文件头部信息

vim ketama.h

#ifndef SSIZE_MAX
#define SSIZE_MAX 32767
#endif

Memcached高可用群集
#编辑Makefile

vi Makefile
LIBS = -levent -lm

#编译(完成后会生成一个manage的可执行文件)

make
Memcached高可用群集

#让服务便于系统识别

cp /opt/magent/magent /usr/bin/
scp /opt/magent/magent root@192.168.5.139:/usr/bin/     //发送到从服务器上

安装keepalived

#主从服务器安装keepalived

yum -y install keepalived

#修改主从服务器配置文件

vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived
global_defs {
   notification_email {
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id MAGENT_H1     //router_id自定义,但是要确保主从一致
}
vrrp_script magent {
        script "/root/shell/magent.sh"
        interval 2                //定义一个函数,此时该脚本还未创建,要在实例外面定义
}
vrrp_instance VI_1 {
    state MASTER           //从为BACKUP
    interface ens33
    virtual_router_id 51   //此处id也相同
    priority 100           //主服务器优先级要高于从服务器
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
track_script {
        magent             //应用函数
}
    virtual_ipaddress {
        192.168.5.100       //定义vtp自定义,只要不是在使用中的地址即可
    }
}                           //配置文件下面还有多余的内容此时就可以直接删除

#建立shell目录

mkdir /root/shell

#创建magent.sh脚本

vim /root/shell/magent.sh

#!/bin/bash

Keepalived=`ps -ef | grep keepalived | grep -v grep | wc -l`
if [ $Keepalived -gt 0 ]; then
        magent -u root -n 51200 -l 192.168.5.100 -p 12000 -s 192.168.5.129:11211 -b 192.168.5.139:11211
else
        pkill -9 magent
fi

参数说明:

    -n 51200                #定义用户最大连接数
    -l 192.168.5.100                #指定虚拟IP
    -p 12000                   #指定端口号
    -s                              #指定主缓存服务器
    -b                              #指定从缓存服务器

#赋予脚本执行权限

chmod +x /root/shell/magent.sh

#启动keepalived服务

systemctl enable keepalived.service
systemctl start keepalived.service

在从服务器上操作

#将主服务器上keepalived配置文件复制过来

scp root@192.168.5.129:/etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf

#编辑keepalived配置文件

vim keepalived.conf

! Configuration File for keepalived

global_defs {
   notification_email {
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id magent_H2              #指定router_id
}

vrrp_script magent {                #定义函数
    script "/root/shell/magent.sh"
    interval 2
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33             #本地网卡名称
    virtual_router_id 51        #id主从一致
    priority 99            #主服务器优先级大于从服务器优先级
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }

    virtual_ipaddress {         #vip地址
        192.168.5.100
    }
    track_script {              #调用函数
        magent
    }
}

#创建magent.sh脚本

mkdir /root/shell
vim /root/shell/magent.sh

#!/bin/bash
Keepalived=`ip addr | grep 192.168.5.100 | grep -v grep | wc -l`
if [ $Keepalived -gt 0 ]; then
        magent -u root -n 51200 -l 192.168.5.100 -p 12000 -s 192.168.5.129:11211 -b 192.168.5.139:11211
else
        pkill -9 magent
fi

#赋予脚本执行权限

chmod +x /root/shell/magent.sh
#启动keepalived服务
systemctl enable keepalived.service
systemctl start keepalived.service

在主从服务器上开启memcached

memcached -m 512k -u root -d -l 192.168.5.129 -p 11211 //主服务器
memcached -m 512k -u root -d -l 192.168.5.139 -p 11211 //从服务器
netstat -ntap | grep 11211

客户端测试连通性

#安装telnet客户端

yum -y install telnet

#连接memcached

telnet 192.168.175.188 12000

#测试复制功能

//连接vip进行测试,插入user键值

[root@localhost ~]# telnet 192.168.5.100 12000
Trying 192.168.5.100...
Connected to 192.168.5.100.
Escape character is '^]'.
set user 0 0 5
test1
STORED
get user
VALUE user 0 5
test1
END
quit
Connection closed by foreign host.

//连接主Memcached,查询user键值,可以获取,成功!
[root@localhost ~]# telnet 192.168.5.129 11211
Trying 192.168.5.129...
Connected to 192.168.5.129.
Escape character is '^]'.

get user
VALUE user 0 5
test1
END
quit
Connection closed by foreign host.

//连接从Memcached,查询user键值,也可以获取,成功!
[root@centos7-1 ~]# telnet 192.168.5.139 11211
Trying 192.168.96.17...
Connected to 192.168.96.17.
Escape character is '^]'.

get user
VALUE user 0 5
test1
END
quit
Connection closed by foreign host.

测试单点故障

关闭主服务器

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客户端连接

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