1.概述
- keepalived使用HA（High Available双机集群系统），指高可用性集群，是保证业务连续性的有效解决方案，一般有两个或两个以上的节点，且分为活动节点及备用节点。
- Keepalived的作用是检测服务器的状态，如果有一台web服务器宕机，或工作出现故障，Keepalived将检测到，并将有故障的服务器从系统中剔除，同时使用其他服务器代替该服务器的工作，当服务器工作正常后Keepalived自动将服务器加入到服务器群中，这些工作全部自动完成，不需要人工干涉，需要人工做的只是修复故障的服务器。
- Keepalived使用VRRP协议实现故障转换
2.特点
解决服务器单点故障问题
- 支持服务器健康状态检查和故障切换
3.VRRP(虚拟路由冗余协议)
将多个设备组成一个备份组
通过公用的虚拟IP对外提供服务
同一时刻只有一台设备提供服务，其余设备处于冗余状态
- 当当前在线设备故障后，由其他设备根据优先级自动替换虚拟IP
二、LVS_DR+Keepalived案例
环境准备：
| 服务器名称 | 作用 | IP地址 |
|---|---|---|
| Web01 | 第一台网站服务器 | 192.168.1.10 |
| Web02 | 第二台网站服务器 | 192.168.1.20 |
| Lvs_ha01 | 第一台网站负载均衡和高可用服务器 | 192.168.1.100 |
| Lvs_ha02 | 第二台网站负载均衡和高可用服务器 | 192.168.1.200 |
| Gateway | 网关（代替路由器） | 192.168.1.1 |
- 群集VIP（virtual IP）地址：192.168.1.254
五台服务器，两台Web、两台LVS，都一块网卡设置为vmnet1；剩余一台为网关，需两块网卡，第一块vmnnet1、第二块桥接
部署Web-1
1.配置IP地址
vim /etc/sysconfig/network-scrips/ifcfg-eth0DEVICE=eth0TYPE=EthernetONBOOT=yesNM_CONTROLLED=noBOOTPROTO=staticIPADDR=192.168.1.10NETMASK=255.255.255.0GATEWAY=192.168.1.1cp /etc/sysconfig/network-scrips/ifcfg-lo /etc/sysconfig/network-scrips/ifcfg-lo:0vim /etc/sysconfig/network-scrips/ifcfg-lo:0DEVICE=lo:0ONBOOT=yesIPADDR=192.168.1.254NETMASK=255.255.255.255/etc/init.d/network restart2.配置安装YUM
rm -rf /etc/yum.repos.d/*vim /etc/yum.repos.d/local.repo[local]name=localbaseurl=file:///mntgpgcheck=0mount /dev/cdrom /mnt3.部署httpd
yum -y install httpd && echo "This is Web1" >/var/www/html/index.html/etc/init.d/httpd start && chkconfig --level 35 httpd on4.修改内核参数和路由
vim /etc/sysctl.confnet.ipv4.conf.all.arp_ignore = 1net.ipv4.conf.all.arp_announce = 2sysctl -proute add -host 192.168.1.254 dev lo:0 && echo "route add -host 192.168.1.254 dev lo:0" >>/etc/rc.local部署Web-2
1.配置IP地址
vim /etc/sysconfig/network-scrips/ifcfg-eth0DEVICE=eth0TYPE=EthernetONBOOT=yesNM_CONTROLLED=noBOOTPROTO=staticIPADDR=192.168.1.20NETMASK=255.255.255.0GATEWAY=192.168.1.1cp /etc/sysconfig/network-scrips/ifcfg-lo /etc/sysconfig/network-scrips/ifcfg-lo:0vim /etc/sysconfig/network-scrips/ifcfg-lo:0DEVICE=lo:0ONBOOT=yesIPADDR=192.168.1.254NETMASK=255.255.255.255/etc/init.d/network restart2.配置安装YUM
rm -rf /etc/yum.repos.d/*vim /etc/yum.repos.d/local.repo[local]name=localbaseurl=file:///mntgpgcheck=0mount /dev/cdrom /mnt3.部署httpd
yum -y install httpd && echo "This is Web2" >/var/www/html/index.html/etc/init.d/httpd start && chkconfig --level 35 httpd on4.修改内核参数和路由
vim /etc/sysctl.confnet.ipv4.conf.all.arp_ignore = 1net.ipv4.conf.all.arp_announce = 2sysctl -proute add -host 192.168.1.254 dev lo:0 && echo "route add -host 192.168.1.254 dev lo:0" >>/etc/rc.local部署LVS+HA-1
1.配置IP
vim /etc/sysconfig/network-scrips/ifcfg-eth0DEVICE=eth0TYPE=EthernetONBOOT=yesNM_CONTROLLED=noBOOTPROTO=staticIPADDR=192.168.1.100NETMASK=255.255.255.0GATEWAY=192.168.1.1/etc/init.d/network restart2.配置YUM并安装依赖包
rm -rf /etc/yum.repos.d/*vim /etc/yum.repos.d/local.repo[local]name=localbaseurl=file:///mntgpgcheck=0mount /dev/cdrom /mntyum -y install kernel-devel openssl-devel popt-devel ?ipvsadm3.安装keepalived
tar zxvf keepalived-1.2.2.tar.gz -C /usr/src/cd /usr/src/keepalived-1.2.2/./configure --prefix=/ --with-kernel-dir=/usr/src/kernels/2.6.32-431.el6.x86_64/make &&make installchkconfig --add keepalived && chkconfig keepalived on4.编辑HA配置文件
vim /etc/keepalived/keepalived.confglobal_defs { ???router_id HA_TEST_R1 ???##本服务器的名称}vrrp_instance VI_1 { ???????##定义VRRP热备实例 ???state MASTER ???????##MASTER表示主服务器 ???interface eth0 ?????##承载VIP地址的物理接口 ???virtual_router_id 1 ????##虚拟路由器的ID号 ???priority 100 ???????##优先级，数值越大优先级越高 ???advert_int 1 ???????##通告间隔秒数（心跳频率） ???authentication { ???????##认证信息 ???????auth_type PASS ?????##认证类型 ???????auth_pass 123456 ???##密码字串 ???} ???virtual_ipaddress { ?192.168.1.254 ????##指定漂移地址（VIP） ???}virtual_server 192.168.1.254 80 { ???????delay_loop 15 ??????##检测时间间隔 ???????lb_algo rr ?????##LVS调度算法 ???????lb_kind DR ?????##LVS的模式 ???????protocol TCPreal_server 192.168.1.10 80 { ???????weight 1 ???????##权值 ???????TCP_CHECK { ???????????????connect_port 80 ????##健康检查端口 ???????????????connect_timeout 3 ??##连接超时时间 ???????????????nb_get_retry 3 ?????##重连次数 ???????????????delay_before_retry 4 ???##重连时间 ???????????????} ???????}real_server 192.168.1.20 80 { ???????weight 1 ???????TCP_CHECK { ???????????????connect_port 80 ???????????????connect_timeout 3 ???????????????nb_get_retry 3 ???????????????delay_before_retry 4 ???????????????} ???????}}5.加载lvs模块
modprobe ip_vs && echo "modprobe ip_vs" >>/etc/rc.local部署LVS+HA-2
1.配置IP
vim /etc/sysconfig/network-scrips/ifcfg-eth0DEVICE=eth0TYPE=EthernetONBOOT=yesNM_CONTROLLED=noBOOTPROTO=staticIPADDR=192.168.1.200NETMASK=255.255.255.0GATEWAY=192.168.1.1/etc/init.d/network restart2.配置YUM并安装依赖包
rm -rf /etc/yum.repos.d/*vim /etc/yum.repos.d/local.repo[local]name=localbaseurl=file:///mntgpgcheck=0mount /dev/cdrom /mntyum -y install kernel-devel openssl-devel popt-devel ?ipvsadm3.安装keepalived
tar zxvf keepalived-1.2.2.tar.gz -C /usr/src/cd /usr/src/keepalived-1.2.2/./configure --prefix=/ --with-kernel-dir=/usr/src/kernels/2.6.32-431.el6.x86_64/make &&make installchkconfig --add keepalived && chkconfig keepalived on4.编辑HA配置文件
scp root@192.168.1.100:/etc/keepalived/keepalived.conf /etc/keepalived/vim /etc/keepalived/keepalived.confglobal_defs { ???router_id HA_TEST_R2 ???##本服务器的名称}vrrp_instance VI_1 { ???????##定义VRRP热备实例 ???state BACKUP ???????##MASTER表示主服务器,BACKUP代表从 ???priority 60 ????????##优先级，数值越大优先级越高5.加载lvs模块
modprobe ip_vs && echo "modprobe ip_vs" >>/etc/rc.localGateway（充当连接公网的路由器）
1.配置IP
vim /etc/sysconfig/network-scrips/ifcfg-eth0DEVICE=eth0TYPE=EthernetONBOOT=yesNM_CONTROLLED=noBOOTPROTO=staticIPADDR=192.168.1.1NETMASK=255.255.255.0cp /etc/sysconfig/network-scrips/ifcfg-eth0 /etc/sysconfig/network-scrips/ifcfg-eth1vim /etc/sysconfig/network-scrips/ifcfg-eth1DEVICE=eth1TYPE=EthernetONBOOT=yesNM_CONTROLLED=noBOOTPROTO=dhcp/etc/init.d/network restart2.开启路由转发
vim /etc/sysctl.conf 7 net.ipv4.ip_forward = 1sysctl -p3.编写防火墙规则
/etc/init.d/iptables stopiptables -t nat -I PREROUTING -d 192.168.10.139 -i eth1 (公网接口) -p tcp --dport 80 -j DNAT --to-destination 192.168.1.254:80/etc/init.d/iptables save && chkconfig --level 35 iptables on访问测试
HA1：/etc/init.d/keepalived restart
HA2：/etc/init.d/keepalived restart ???//重启keepalived服务
IE：http://192.168.10.139 ???//访问公网地址测试故障转移
LVS_DR+Keepalived高可用Web群集
原文地址：http://blog.51cto.com/13770206/2161911