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说明：
操作系统：CentOS 5.X 64位
MySQL主服务器：192.168.21.126
MySQL从服务器：192.168.21.127，192.168.21.128
MySQL主从同步的数据库为：osyunweidb
实现目的：
增加两台服务器（主备），通过LVS+Keepalived实现MySQL从库读操作负载均衡
架构规划：
操作系统：CentOS 5.X 64位
LVS主服务器：192.168.21.129
LVS备服务器：192.168.21.130
LVS虚拟服务器（VIP）：192.168.21.254
部署完成之后，通过VIP：192.168.21.254，根据LVS调度算法来访问后端真实的MySQL从服务器，实现负载均衡。
首先是安装软件：
Keepalive安装
keepalived下载地址
需要安装以下软件包
# yum install -y kernel-devel openssl openssl-devel
解压keepalived到/usr/local/并进入目录执行配置编译
# ./configure --prefix=/usr/local/keepalived --with-kernel-dir=/usr/src/kernels/2.6.32-431.5.1.el6.x86_64/
Keepalived configuration
------------------------
Keepalived version : 1.2.13
Compiler : gcc
Compiler flags : -g -O2
Extra Lib : -lssl -lcrypto -lcrypt
Use IPVS Framework : Yes
IPVS sync daemon support : Yes
IPVS use libnl : No
fwmark socket support : Yes
Use VRRP Framework : Yes
Use VRRP VMAC : Yes
SNMP support : No
SHA1 support : No
Use Debug flags : No# make && make install
默认情况下keepalived启动时会去/etc/keepalived目录下找配置文件，将需要的配置文件拷贝到指定位置
# cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
# cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
# cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
# cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
# chkconfig mysqld on
# chkconfig keepalived on
LVS安装
ipvsadm下载地址
需要安装以下软件包
# yum install -y libnl* popt*
查看是否加载lvs模块
# modprobe -l |grep ipvs
解压安装
# ln -s /usr/src/kernels/2.6.32-431.5.1.el6.x86_64/ /usr/src/linux
# tar -zxvf ipvsadm-1.26.tar.gz
# make && make install
LVS安装完成，查看当前LVS集群
# ipvsadm -L -n
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn具体操作：
第一部分：分别在两台MySQL从服务器上操作
一、关闭SELINUX
vi /etc/selinux/config
#SELINUX=enforcing #注释掉
#SELINUXTYPE=targeted #注释掉
SELINUX=disabled #增加
:wq! #保存退出
setenforce 0 #使配置立即生效
二、配置防火墙，开启3306端口
vi /etc/sysconfig/iptables #编辑
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 3306 -j ACCEPT #允许3306端口通过防火墙
:wq! #保存退出
/etc/init.d/iptables restart #重启防火墙使配置生效
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三、绑定LVS虚拟服务器（VIP）：192.168.21.254到lo:0
vi /etc/rc.d/init.d/realserver #编辑，添加以下代码
#################################################
#!/bin/sh
# chkconfig: - 80 90
# description:realserver
# mysql_vip start realserver
mysql_vip=192.168.21.254 #LVS虚拟服务器（VIP）
. /etc/rc.d/init.d/functions
case "$1" in
start)
ifconfig lo:0 $mysql_vip netmask 255.255.255.255 broadcast $mysql_vip
/sbin/route add -host $mysql_vip dev lo:0
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
sysctl -p >/dev/null 2>&1
echo "RealServer Start OK"
;;
stop)
ifconfig lo:0 down
route del $mysql_vip >/dev/null 2>&1
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 "RealServer Stoped"
;;
*)
echo "Usage: $0 {start|stop}"
exit 1
esac
exit 0
#################################################
chmod +x /etc/rc.d/init.d/realserver #添加脚本执行权限
chkconfig realserver on #添加开机启动
/etc/rc.d/init.d/realserver start #开启，参数stop为关闭
四、调整服务器参数，使LVS虚拟服务器（VIP）忽略ARP广播包
vi /etc/sysctl.conf #编辑
net.ipv4.ip_forward= 1 #修改0为1，开启转发
net.ipv4.conf.lo.arp_ignore= 1
net.ipv4.conf.lo.arp_announce= 2
net.ipv4.conf.all.arp_ignore= 1
net.ipv4.conf.all.arp_announce= 2
:wq! #保存退出
/sbin/sysctl -p #使配置立即生效
五、设置能够远程监控MySQL主从同步状态的MySQL用户和密码
mysql -u root -p #进入MySQL控制台
insert into mysql.user(Host,User,Password) values('localhost','checkslave',password('123456')); #新建账户checkslave，密码123456
flush privileges; #刷新系统授权表
grant all on *.* to 'checkslave'@'192.168.21.129' identified by '123456' with grant option; #允许账户checkslave从LVS主服务器192.168.21.129连接到数据库服务器
grant all on *.* to 'checkslave'@'192.168.21.130' identified by '123456' with grant option; #允许账户checkslave从LVS从服务器192.168.21.130连接到数据库服务器
第二部分：分别在两台LVS主备服务器上操作
一、关闭SElinux、配置防火墙
1、vi /etc/selinux/config
#SELINUX=enforcing #注释掉
#SELINUXTYPE=targeted #注释掉
SELINUX=disabled #增加
:wq! #保存退出
setenforce 0 #使配置立即生效
2、vi /etc/sysconfig/iptables #编辑
-A RH-Firewall-1-INPUT -d 224.0.0.18 -j ACCEPT #允许VRRP（虚拟路由器冗余协议）组播地址通信
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 3306 -j ACCEPT #允许3306端口通过防火墙
:wq! #保存退出
/etc/init.d/iptables restart #重启防火墙使配置生效
二、安装lvs软件
yum install ipvsadm #Linux 2.6内核已经集成了lvs软件，此处ipvsadm为lvs管理工具
modprobe ip_vs #加载ip_vs
三、安装keepalived
yum install gcc gcc-c++ make openssl-devel kernel-devel ncurses-devel #安装编译工具包
下载keeplived：http://www.keepalived.org/software/keepalived-1.2.12.tar.gz
上传keepalived-1.2.12.tar.gz到/usr/local/src目录
cd /usr/local/src
tar zxvf keepalived-1.2.12.tar.gz
cd keepalived-1.2.12
./configure #配置，必须看到以下提示，说明配置正确，才能继续安装
Use IPVS Framework : Yes
IPVS sync daemon support : Yes
Use VRRP Framework : Yes
make #编辑
make install #安装
cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
mkdir /etc/keepalived
cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/
cp /usr/local/sbin/keepalived /usr/sbin/
cp /usr/local/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
chmod +x /etc/rc.d/init.d/keepalived #添加执行权限
chkconfig keepalived on #设置开机启动
service keepalived start #启动
service keepalived stop #关闭
service keepalived restart #重启
四、安装perl、perl-DBI、DBD-mysql模块以及MySQL客户端 #perl脚本连接MySQL数据库需要
yum install perl perl-DBI perl-DBD-MySQL mysql #执行此命令安装
vi /tmp/test_perl.pl
#!/usr/bin/perl
print "Hello, world!\n";
:wq! #保存退出
perl /tmp/test_perl.pl #运行测试脚本，如果出现：Hello,world! 说明perl安装成功
perldoc DBI #查看DBI模块是否安装
perldoc DBD::mysql #查看DBD::mysql模块是否安装
五、配置keepalived
cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf-bak
vi /etc/keepalived/keepalived.conf #编辑，修改为以下代码
##################################################################################################
! 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 LVS_DEVEL
}
vrrp_instance VI_1 {
state MASTER #LVS备机修改为BACKUP
interface eth0
virtual_router_id 51
priority 100 #LVS备机修改为80
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.21.254
}
notify_master "/etc/keepalived/clean_arp.sh" #LVS主备机都为notify_master
}
virtual_server 192.168.21.254 3306 {
delay_loop 30
lb_algo wlc
lb_kind DR
#nat_mask 255.255.255.0
persistence_timeout 120
protocol TCP
real_server 192.168.21.127 3306 {
weight 1
MISC_CHECK {
misc_path "/etc/keepalived/check_slave.pl 192.168.21.127"
misc_dynamic
}
}
real_server 192.168.21.128 3306 {
weight 1
MISC_CHECK {
misc_path "/etc/keepalived/check_slave.pl 192.168.21.128"
misc_dynamic
}
}
##################################################################################################
:wq! #保存退出
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六、设置MySQL主从监控脚本check_slave.pl
vi /etc/keepalived/check_slave.pl #编辑，添加以下代码
##################################################################################################
#!/usr/bin/perl -w
use DBI;
use DBD::mysql;
# CONFIG VARIABLES
$SBM = 120;
$db = "osyunweidb";
$host = $ARGV[0];
$port = 3306;
$user = "checkslave";
$pw = "123456";
# SQL query
$query = "show slave status";
$dbh = DBI->connect("DBI:mysql:$db:$host:$port", $user, $pw, { RaiseError => 0,PrintError => 0 });
if (!defined($dbh)) {
exit 1;
}
$sqlQuery = $dbh->prepare($query);
$sqlQuery->execute;
$Slave_IO_Running = "";
$Slave_SQL_Running = "";
$Seconds_Behind_Master = "";
while (my $ref = $sqlQuery->fetchrow_hashref()) {
$Slave_IO_Running = $ref->{'Slave_IO_Running'};
$Slave_SQL_Running = $ref->{'Slave_SQL_Running'};
$Seconds_Behind_Master = $ref->{'Seconds_Behind_Master'};
}
$sqlQuery->finish;
$dbh->disconnect();
if ( $Slave_IO_Running eq "No" || $Slave_SQL_Running eq "No" ) {
exit 1;
} else {
if ( $Seconds_Behind_Master > $SBM ) {
exit 1;
} else {
exit 0;
}
}
##################################################################################################
:wq! #保存退出
chmod +x /etc/keepalived/check_slave.pl #添加脚本执行权限
七、设置更新LVS虚拟服务器（VIP）地址的arp记录到网关脚本
vi /etc/keepalived/clean_arp.sh #编辑，添加以下代码
#!/bin/sh
VIP=192.168.21.254
GATEWAY=192.168.21.2
/sbin/arping -I eth0 -c 5 -s $VIP $GATEWAY &>/dev/null
:wq! #保存退出
chmod +x /etc/keepalived/clean_arp.sh #添加脚本执行权限
八、测试LVS+Keepalived是否正常运行
service keepalived restart #在两台LVS主备服务器上重启keepalived
ipvsadm -L #在两台LVS主备服务器上执行此命令，看到如下图所示
ip addr show #在两台LVS主备服务器上执行此命令，看到如下图所示
#从图中可以看到VIP：192.168.21.254现在指向的是LVS主服务器
1、关闭LVS主服务器的keepalived服务，查看LVS备服务器是否正常接管keepalived
service keepalived stop #在LVS主服务器上运行
此时，在两台LVS主备服务器上执行ip addr show命令，如下图所示
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可以看到VIP：192.168.21.254现在指向的是LVS备服务器，说明LVS备服务器已经接管keepalived，测试成功。
2、停止MySQL从服务器192.168.21.127上面的主从同步服务
mysql -u root -p #进入MySQL控制台
slave start; #停止同步
在LVS备服务器执行ipvsadm -L命令，可以看到MySQL从服务器192.168.21.127已经从负载均衡列表中被剔除了，测试成功。
3、从客户端连接LVS虚拟服务器（VIP）：192.168.21.254
telnet 192.168.21.254 3306 #执行此命令，如下图所示，说明测试成功。
tail -f /var/log/messages #查看LVS日志信息
至此，LVS+Keepalived实现MySQL从库读操作负载均衡配置完成。
如果你的mysql是主主复制模式那么可以采用单点写入实现高可用
只需要将主lvs跟备用lvs进行如下改写即可
! 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 LVS_DEVEL
}
vrrp_instance VI_1 {
state MASTER #LVS备机修改为BACKUP
interface eth0
virtual_router_id 51
priority 100 #LVS备机修改为80
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.21.254
}
notify_master "/etc/keepalived/clean_arp.sh" #LVS主备机都为notify_master
}
virtual_server 192.168.21.254 3306 {
delay_loop 30
lb_algo wlc
lb_kind DR
#nat_mask 255.255.255.0
persistence_timeout 120
protocol TCP
sorry_server 192.168.21.128 3306
real_server 192.168.21.127 3306 {
weight 1
MISC_CHECK {
misc_path "/etc/keepalived/check_slave.pl 192.168.21.127"
misc_dynamic
}
}
}
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