最近公司網站訪問又見瓶頸，為了緩解壓力，決定用LVS+Keepalived來實現負載均衡.在前面的文章中已經寫過了用NAT模式來實現負載均衡 http://duyunlong.blog.51cto.com/1054716/716138，而今天用的是DR模式，其實NAT跟DR模式，各有優缺點，根據實際情況來選擇適合自己的。下面看下具體步驟以及注意事項。
拓撲圖如下：
首先看下我用的系統，系統為centos6.2，64位系統，用getconf LONG_BIT,和uname -a都可以查看
[root@localhost src]# getconf LONG_BIT
64
[root@localhost src]# uname -a
Linux localhost 2.6.32-279.19.1.el6.x86_64 #1 SMP Wed Dec 19 07:05:20 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
然後，分析下搭建這個LVS+Keepalived（DR）需要的關鍵步驟及注意事項，第一、DR模式主要是靠虛擬IP來實現，那麼每台機器都需要建立 一個虛擬IP，這個是必需的，第二、要注意的就是popt-static-1.13-7.el6.x86_64.rpm這個包，不裝這個包，安裝ipvs 的時候會報錯，第三、就是一些零碎的配置。
[root@localhost src]# wget http://www.keepalived.org/software/keepalived-1.2.2.tar.gz
[root@localhost src]# wget http://www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.26.tar.gz
[root@localhost src]# wget http://mirror.centos.org/centos/6/os/x86_64/Packages/popt-static-1.13-7.el6.x86_64.rpm
然後，在LVS主跟備份上安裝
[root@localhost src]# rpm -ivh popt-static-1.13-7.el6.x86_64.rpm
[root@localhost src]# yum -y install kernel-devel make gcc openssl-devel libnl* popt*
[root@localhost src]# ln -s /usr/src/kernels/2.6.32-220.13.1.el6.x86_64/ /usr/src/linux
[root@localhost src]# tar -zxvf ipvsadm-1.26.tar.gz
[root@localhost src]# cd ipvsadm-1.26/
[root@localhost ipvsadm-1.26]# make
[root@localhost ipvsadm-1.26]# make install
[root@localhost ipvsadm-1.26]# cd ..
[root@localhost src]# tar -zxvf keepalived-1.2.2.tar.gz -C /usr/src/
[root@localhost src]# cd keepalived-1.2.2/
[root@localhost keepalived-1.2.2]# ./configure
[root@localhost keepalived-1.2.2]# make
[root@localhost keepalived-1.2.2]# make install
[root@localhost keepalived-1.2.2]# cp /usr/local/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
[root@localhost keepalived-1.2.2]# cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
[root@localhost keepalived-1.2.2]# mkdir /etc/keepalived
[root@localhost keepalived-1.2.2]# cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/[root@localhost keepalived-1.2.2]# cp /usr/local/sbin/keepalived /usr/sbin/
在兩台LVS上分別配置keepalived， vim /etc/keepalived/keepalived.conf
[root@localhost src]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
router_id LVS_MASTER #網上資料說這個值也需要修改，具體不詳，之前我們線上的主備就一直是一樣的 ^ ^還是修改一下吧！
}
vrrp_instance VI_1 {
state MASTER #LVS_Backup上修改成BACKUP
interface eth0
virtual_router_id 60 #默認51 主從都修改為60
priority 100 #LVS_Backup上修改成80
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.10.100
}
}
virtual_server 192.168.10.100 80 {
delay_loop 6
lb_algo rr
lb_kind DR
nat_mask 255.255.255.0
persistence_timeout 50
protocol TCP
real_server 192.168.10.3 80 {
weight 1
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
connect_port 80
}
}
real_server 192.168.10.4 80 {
weight 1
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
connect_port 80
}
}
}
在LVS_Backup上也進行配置，只要把標紅的地方改下就OK,然後我們在真實機上配置虛擬IP啟動腳本
[root@localhost src]# vim /etc/init.d/realserver.sh
#!/bin/bash
SNS_VIP=192.168.10.100
. /etc/rc.d/init.d/functions
case "$1" in
start)
ifconfig lo:0 $SNS_VIP netmask 255.255.255.255 broadcast $SNS_VIP
/sbin/route add -host $SNS_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 $SNS_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
在兩台真是機器上面配置apache並啟動realserver.sh
[root@localhost src]# yum -y install httpd
[root@localhost src]# cd /var/www/html/
[root@localhost html]# cat index.html < h1>RealServer 192.168.10.3</h1>
[root@localhost html]# /etc/init.d/httpd start
[root@localhost src]# /etc/init.d/realserver.sh start
配置完後我們來測試下：分別啟動Keepalived
[root@localhost src]# chkconfig keepalived on
[root@localhost src]# /etc/init.d/keepalived restart
[root@localhost src]# ipvsadm
IP Virtual Server version 1.2.1
(size=4096)Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 192.168.10.100:http rr persistent 50
-> 192.168.10.3:http Route 1 0 0
-> 192.168.10.4:http Route 1 0 0
關閉LVS_MASTER，然後查看LVS_backup日志
[root@localhost src]# tail -f /var/log/messages
Mar 21 07:22:28 host2 Keepalived_vrrp: VRRP_Instance(VI_1)
Transition to MASTER STATE
Mar 21 07:22:29 host2 Keepalived_vrrp: VRRP_Instance(VI_1)
Entering MASTER STATE
Mar 21 07:22:29 host2 Keepalived_vrrp: VRRP_Instance(VI_1)
setting protocol VIPs.
Mar 21 07:22:29 host2 Keepalived_healthcheckers: Netlink
reflector reports IP 192.168.10.100 added
Mar 21 07:22:29 host2 Keepalived_vrrp: VRRP_Instance(VI_1)
Sending gratuitous ARPs on eth0 for 192.168.10.100
測試訪問
[root@localhost html]# curl http://192.168.10.100
< h1>RealServer 192.168.10.4</h1>
然後，啟動LVS_MASTER查看LVS_BACKUP日志
[root@localhost src]# tail -f /var/log/messages
Mar 21 07:26:20 host2 Keepalived_vrrp: VRRP_Instance(VI_1)
Received higher prio advert
Mar 21 07:26:20 host2 Keepalived_vrrp: VRRP_Instance(VI_1)
Entering BACKUP STATE
Mar 21 07:26:20 host2 Keepalived_vrrp: VRRP_Instance(VI_1)
removing protocol VIPs.
Mar 21 07:26:20 host2 Keepalived_healthcheckers: Netlink
reflector reports IP 192.168.10.100 removed
