LVS+Keepalived构建高可用负载均衡(测试篇)
一、 启动LVS高可用集群服务
首先，启动每个real server节点的服务：
[root@localhost ~]# /etc/init.d/lvsrs start
start LVS of REALServer
然后，分别在主备Director Server启动Keepalived服务：
[root@DR1 ~]#/etc/init.d/Keepalived start
[root@DR1 ~]#/ ipvsadm -L
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP bogon:http rr
-> real-server1:http Route 1 1 0
-> real-server2:http Route 1 1 0
此时查看Keepalived服务的系统日志信息如下:
[root@localhost ~]# tail -f /var/log/messages
Feb 28 10:01:56 localhost Keepalived: Starting Keepalived v1.1.19 (02/27,2011)
Feb 28 10:01:56 localhost Keepalived_healthcheckers: Netlink reflector reports IP 192.168.12.25 added
Feb 28 10:01:56 localhost Keepalived_healthcheckers: Opening file '/etc/keepalived/keepalived.conf'.
Feb 28 10:01:56 localhost Keepalived_healthcheckers: Configuration is using : 12063 Bytes
Feb 28 10:01:56 localhost Keepalived: Starting Healthcheck child process, pid=4623
Feb 28 10:01:56 localhost Keepalived_vrrp: Netlink reflector reports IP 192.168.12.25 added
Feb 28 10:01:56 localhost Keepalived: Starting VRRP child process, pid=4624
Feb 28 10:01:56 localhost Keepalived_healthcheckers: Activating healtchecker for service [192.168.12.246:80]
Feb 28 10:01:56 localhost Keepalived_vrrp: Opening file '/etc/keepalived/keepalived.conf'.
Feb 28 10:01:56 localhost Keepalived_healthcheckers: Activating healtchecker for service [192.168.12.237:80]
Feb 28 10:01:57 localhost Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE
Feb 28 10:01:58 localhost Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE
Feb 28 10:01:58 localhost Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.
Feb 28 10:01:58 localhost Keepalived_healthcheckers: Netlink reflector reports IP 192.168.12.135 added
Feb 28 10:01:58 localhost avahi-daemon[2778]: Registering new address record for 192.168.12.135 on eth0.
二、 高可用性功能测试
高可用性是通过LVS的两个Director Server完成的，为了模拟故障，我们先将主Director Server上面的Keepalived服务停止，然后观察备用Director Server上Keepalived的运行日志，信息如下：
Feb 28 10:08:52 lvs-backup Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE
Feb 28 10:08:54 lvs-backup Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE
Feb 28 10:08:54 lvs-backup Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.
Feb 28 10:08:54 lvs-backup Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.12.135
Feb 28 10:08:54 lvs-backup Keepalived_vrrp: Netlink reflector reports IP 192.168.12.135 added
Feb 28 10:08:54 lvs-backup Keepalived_healthcheckers: Netlink reflector reports IP 192.168.12.135 added
Feb 28 10:08:54 lvs-backup avahi-daemon[3349]: Registering new address record for 192.168.12.135 on eth0.
Feb 28 10:08:59 lvs-backup Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.12.135
从日志中可以看出，主机出现故障后，备机立刻检测到，此时备机变为MASTER角色，并且接管了主机的虚拟IP资源，最后将虚拟IP绑定在eth0设备上。
接着，重新启动主Director Server上的Keepalived服务，继续观察备用Director Server的日志状态：
备用Director Server的日志状态：
Feb 28 10:12:11 lvs-backup Keepalived_vrrp: VRRP_Instance(VI_1) Received higher prio advert
Feb 28 10:12:11 lvs-backup Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE
Feb 28 10:12:11 lvs-backup Keepalived_vrrp: VRRP_Instance(VI_1) removing protocol VIPs.
Feb 28 10:12:11 lvs-backup Keepalived_vrrp: Netlink reflector reports IP 192.168.12.135 removed
Feb 28 10:12:11 lvs-backup Keepalived_healthcheckers: Netlink reflector reports IP 192.168.12.135 removed
Feb 28 10:12:11 lvs-backup avahi-daemon[3349]: Withdrawing address record for 192.168.12.135 on eth0.
从日志可知，备机在检测到主机重新恢复正常后，重新返回BACKUP角色，并且释放了虚拟IP资源。
三、 负载均衡测试
这里假定两个real server节点配置www服务的网页文件根目录均为/webdata/www目录，然后分别执行如下操作：
在real server1 执行：
echo "This is real server1" /webdata/www/index.html
在real server2 执行：
echo "This is real server2" /webdata/www/index.html
接着打开浏览器，访问http://192.168.12.135这个地址，然后不断刷新此页面，如果能分别看到“This is real server1”和“This is real server2”就表明LVS已经在进行负载均衡了。
四、 故障切换测试
故障切换是测试当某个节点出现故障后，Keepalived监控模块是否能及时发现，然后屏蔽故障节点，同时将服务转移到正常节点来执行。
这里我们将real server 1节点服务停掉，假定这个节点出现故障，然后查看主、备机日志信息，相关日志如下：
Feb 28 10:14:12 localhost Keepalived_healthcheckers: TCP connection to [192.168.12.246:80] failed !!!
Feb 28 10:14:12 localhost Keepalived_healthcheckers: Removing service [192.168.12.246:80] from VS [192.168.12.135:80]
Feb 28 10:14:12 localhost Keepalived_healthcheckers: Remote SMTP server [192.168.12.1:25] connected.
Feb 28 10:14:12 localhost Keepalived_healthcheckers: SMTP alert successfully sent.
通过日志可以看出，Keepalived监控模块检测到192.168.12.246这台主机出现故障后，将此节点从集群系统中剔除掉了。
此时访问http://192.168.12.135这个地址，应该只能看到“This is real server2”了，这是因为节点1出现故障，而Keepalived监控模块将节点1从集群系统中剔除了。
下面重新启动real server 1节点的服务，可以看到Keepalived日志信息如下：
Feb 28 10:15:48 localhost Keepalived_healthcheckers: TCP connection to [192.168.12.246:80] success.
Feb 28 10:15:48 localhost Keepalived_healthcheckers: Adding service [192.168.12.246:80] to VS [192.168.12.135:80]
Feb 28 10:15:48 localhost Keepalived_healthcheckers: Remote SMTP server [192.168.12.1:25] connected.
Feb 28 10:15:48 localhost Keepalived_healthcheckers: SMTP alert successfully sent.
从日志可知，Keepalived监控模块检测到192.168.12.246这台主机恢复正常后，又将此节点加入了集群系统中。
此时再次访问http://192.168.12.135这个地址，然后不断刷新此页面，应该又能分别看到“This is real server1”和“This is real server2”页面了，这说明在real server 1节点恢复正常后，Keepalived监控模块将此节点加入了集群系统中。