keepalived+lvs实现对mysql读负载均衡
环境：redhat 6.5
real server: 172.25.254.189 172.25.254.224 lvs: 172.25.254.5 172.25.254.112给real server端配置VIP，写脚本
#!/bin/bashVIP=172.25.254.222. /etc/init.d/functionscase "$1" in start) /sbin/ifconfig lo:0 $VIP broadcast netmask 255.255.255.255 up echo "real server lvs start" echo "1" > /proc/sys/net/ipv4/conf/lo/arp_ignore echo "2" > /proc/sys/net/ipv4/conf/lo/arp_announce echo "1" > /proc/sys/net/ipv4/conf/all/arp_ignore echo "2" > /proc/sys/net/ipv4/conf/all/arp_announce ;; stop) /sbin/ifconfig lo:0 down echo "real server lvs stop" echo "0" > /proc/sys/net/ipv4/conf/lo/arp_ignore echo "0" > /proc/sys/net/ipv4/conf/lo/arp_announce echo "0" > /proc/sys/net/ipv4/conf/all/arp_ignore echo "0" > /proc/sys/net/ipv4/conf/all/arp_announce ;; *) echo "Usage: $0 (start|stop)" exit 1esacexit 0
配置lvs和keepalived
安装ipvsadmyum install ipvsadm -y 在两台调度端上安装keepalived tar zxf keepalived-1.2.19.tar.gz yum install -y libnl-devel openssl-devel gcc./configure --prefix=/usr/local/keepalived make make installscp -r /usr/local/keepalived/ 172.25.7.4:/usr/local/
两台lvs上配置
ln -s /usr/local/keepalived/etc/keepalived/ /etc/ ##配置文件 ln -s /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/ ln -s /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/ ##启动脚本ln -s /usr/local/keepalived/sbin/keepalived /sbin/
对keepalived的配置
vim /etc/keepalived/keepalived.conf vrrp_instance VI_1 { ##vrrp虚拟路由协议 14 state MASTER ##备机改为BACKUP，此状态是由priority的值来决定的，当前的优先级值小于备机的值，则将会失去MASTER状态 15 interface eth0 ##HA监测网络接口，用于心跳信息的传递 16 virtual_router_id 7 ##主备机的虚拟路由id必须相同，取值0-255 17 priority 100 ##主机的优先级，备份机改为90，主机优先级一定大于 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 172.25.254.222 }}virtual_server 172.25.254.222 3306 { delay_loop 3 lb_algo rr lb_kind DR # nat_mask 255.255.255.0 # persistence_timeout 50 protocol TCP real_server 172.25.254.189 3306{ weight 1 TCP_CHECK { connect_timeout 3 nb_get_retry 3 delay_before_retry 3 } } real_server 172.25.254.224 3306{ weight 1 TCP_CHECK { connect_timeout 3 nb_get_retry 3 delay_before_retry 3 } }} 对两台real server的mysql做主从复制，然后开启服务，具体的主从复制步骤可以查看mysql的笔记
sh /etc/lvs.sh start/etc/init.d/mysqld start
调度端
[root@server5 mail]# /etc/init.d/keepalived restartStopping keepalived: [ OK ]Starting keepalived: [ OK ][root@server5 mail]# ipvsadm -LIP Virtual Server version 1.2.1 (size=4096)Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConnTCP 172.25.254.111:http rr -> localhost:http Local 1 0 0 TCP 172.25.254.222:mysql rr -> sky.example.com:mysql Route 1 0 0 -> server0.example.com:mysql Route 1 0 0
常见问题
1）为什么同一个IP的某一个时间段访问的都分配到同一个real server.
LVS的持久链接有两种，持久时间工作原理
当一个新的请求进来的时候，就创建了一个此IP的信息，并添加一个state为none的记录，该记录有效期会轮询至此ip端的链接信息的超时退出DIRCTOR。
2） RealServer 为什么要在 lo 接口上配置 VIP,在出口网卡上配置 VIP 可以吗?既然要让 RS 能够处理目标地址为 vip 的 IP 包,首先必须要让 RS 能接收到这个包。在 lo 上配置 vip 能够完成接收包并将结果返回 client。
答案是不可以将 VIP 设置在出口网卡上,否则会响应客户端的 arp request,造成 client/gatewayarp table 紊乱,以至于整个 loadbalance 都不能正常工作
3) RealServer 为什么要抑制 arp 帧?这个问题在上一问题中已经作了说明,这里结合实施命令进一步阐述。我们在具体实施部署的时候都会作如下调整:
echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignoreecho "2">/proc/sys/net/ipv4/conf/lo/arp_announceecho "1">/proc/sys/net/ipv4/conf/all/arp_ignoreecho "2">/proc/sys/net/ipv4/conf/all/arp_announce
4）脑裂：
如果实际生产环境中为了避免脑裂问题，需要把BACKUP和MATER的优先级设置的不一样。