环境说明： 本系统对数据安全性不高，TPS操作很低，主要是查询的环境。
本方案架构图如下： 应用服务器对只读的应用程序连接虚拟IP地址，连接到haproxy，然后通过haproxy将TCP协议转移到下面的3个数据库服务器中。Haproxy在此做4层的TCP交换服务。keepalived为了防止haproxy单点故障。 为什么不用LVS？ 我们的环境服务器少，haproxy和lvs相比性能差不多，且haproxy自带有mysql check，不需要额外的写mysql侦测脚本。


1.haproxy安装
下载地址：http://www.haproxy.org/download/1.5/src/haproxy-1.5.5.tar.gz
依赖包安装：#yum install gcc gcc-c++ make zlib-devel bzip2-devel openssl-devel

安装pcre，自带的pcre-7.8-3.1.el6.x86_64貌似版本低了，导致无法安装proxy
#tar xzvf pcre-8.34.tar.gz
#cd pcre-8.34#./configure --prefix=/usr \--docdir=/usr/share/doc/pcre-8.34 \--enable-utf --enable-unicode-properties \--enable-pcregrep-libz --enable-pcregrep-libbz2#make#make check#make install

script "/etc/keepalived/check_haproxy.sh"interval 2weight 2

global_defs {router_id LVS_DEVEL}
vrrp_instance VI_1 {state MASTERinterface bond0virtual_router_id 51priority 150advert_int 1authentication {auth_type PASSauth_pass 1111} track_script {chk_http_port} virtual_ipaddress {192.168.231.18}}}
配置侦测haproxy状态脚本：#vi /etc/keepalived/check_haproxy.sh#!/bin/bashA=`ps -C haproxy --no-header |wc -l`if [ $A -eq 0 ];then /usr/local/sbin/haproxy -f /etc/haproxy/haproxy.confsleep 3
if [ `ps -C haproxy --no-header |wc -l` -eq 0 ];then /etc/init.d/keepalived stopfifi
启动keepalived服务：# /etc/init.d/keepalived start

添加新的协议地址：#ip add[root@mss-dn03 ~]# ip add1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN qlen 1000 link/ether 90:e2:ba:23:87:04 brd ff:ff:ff:ff:ff:ff3: eth2: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN qlen 1000 link/ether 90:e2:ba:23:87:05 brd ff:ff:ff:ff:ff:ff
9: bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP link/ether 6c:ae:8b:26:52:3b brd ff:ff:ff:ff:ff:ff inet 192.168.231.7/24 brd 192.168.231.255 scope global bond0 inet6 fe80::6eae:8bff:fe26:523b/64 scope link tentative dadfailed valid_lft forever preferred_lft forever
设置开启自启动：# chkconfig --level 0123456 keepalived on# chkconfig --list keepalived

测试过程中发现，master宕机后，VIP需要几十秒才能ping通，切换很慢：arping -I bond0 -c 5 -s VIP GATEWAY#arping -I bond0 -c 5 -s 192.168.231.18 192.168.231.254


Getting started with HAProxy and MySQL replication（能实现读写路由）：
http://blog.yannickjaquier.com/linux/getting-started-with-haproxy-and-mysql-replication.html Haproxy配置日志： http://www.linuxidc.com/Linux/2012-06/63585.htm

来自为知笔记(Wiz)