三部分实现负载均衡

LVS大家应该都有所耳闻，它是一个很好实现负载均衡的平台。节约成本，又容易操作。是一款经济实用的虚拟软件，而且也飞上容易上手。那么，我们现在就来具体叙述一下实现负载均衡的代码，其中我们把具体的步骤分为三大部分，结构很清晰。

IP明细： 1.LVS-DR-Master 61.164.122.6 2.LVS-DR-BACKUP 61.164.122.7 3.LVS-DR-VIP 61.164.122.8 4.WEB1-Realserver 61.164.122.9 5.WEB2-Realserver 61.164.122.10 6.GateWay 61.164.122.1

安装LVS和Keepalvied软件包

1.下载相关软件包

1.#mkdir /usr/local/src/lvs
2.#cd /usr/local/src/lvs
3.#wget http://www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.24.tar.gz
4.#wget http://www.keepalived.org/software/keepalived-1.1.15.tar.gz

2.安装LVS和Keepalived

1.#lsmod |grep ip_vs
2.#uname -r
3.2.6.18-53.el5PAE
4.#ln -s /usr/src/kernels/2.6.18-53.el5PAE-i686//usr/src/linux
5.
6.#tar zxvf ipvsadm-1.24.tar.gz
7.#cd ipvsadm-1.24
8.#make && make install
9.#find / -name ipvsadm# 查看ipvsadm的位置
10.
11.#tar zxvf keepalived-1.1.15.tar.gz
12.#cd keepalived-1.1.15
13.#./configure&& make && make install
14.#find / -name keepalived# 查看keepalived位置
15.
16.#cp /usr/local/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
17.#cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
18.#mkdir /etc/keepalived
19.#cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/
20.#cp /usr/local/sbin/keepalived /usr/sbin/
21.#service keepalived start|stop#做成系统启动服务方便管理.

#p#配置LVS实现负载均衡 1.LVS-DR，配置LVS脚本实现负载均衡 注: 此脚本在于演示方便大家理解lvs,在keepalived方案中不要启动此脚本，所以看后面有注掉，很多朋友对此有问题。关于LVS的 keepalvied的HA方案，完全由keepalived.conf 一个文件搞定，特此声明！

1.#vi /usr/local/sbin/lvs-dr.sh
2.#!/bin/bash
3.# description: start LVS of DirectorServer
4.#Written by :NetSeek http://www.linuxtone.org
5.
6.GW=61.164.122.1
7.# website director vip.
8.SNS_VIP=61.164.122.8
9.SNS_RIP1=61.164.122.9
10.SNS_RIP2=61.164.122.10
11.
12../etc/rc.d/init.d/functions
13.
14.logger $0 called with $1
15.
16.case "$1" in
17.
18.start)
19.# set squid vip
20./sbin/ipvsadm --set 30 5 60
21./sbin/ifconfig eth0:0 $SNS_VIP broadcast $SNS_VIP netmask 255.255.255.255 broadcast $SNS_VIP up
22./sbin/route add -host $SNS_VIP dev eth0:0
23./sbin/ipvsadm -A -t $SNS_VIP:80 -s wrr -p 3
24./sbin/ipvsadm -a -t $SNS_VIP:80 -r $SNS_RIP1:80 -g -w 1
25./sbin/ipvsadm -a -t $SNS_VIP:80 -r $SNS_RIP2:80 -g -w 1
26.touch /var/lock/subsys/ipvsadm >/dev/null 2>&1
27.
28.;;
29.stop)
30./sbin/ipvsadm -C
31./sbin/ipvsadm -Z
32.ifconfig eth0:0 down
33.route del $SNS_VIP
34.rm -rf /var/lock/subsys/ipvsadm >/dev/null 2>&1
35.echo "ipvsadm stoped"
36.;;
37.
38.status)
39.
40.if [ ! -e /var/lock/subsys/ipvsadm ];then
41.echo "ipvsadm stoped"
42.exit 1
43.else
44.echo "ipvsadm OK"
45.fi
46.;;
47.
48.*)
49.echo "Usage: $0 {start|stop|status}"
50.exit 1
51.esac
52.
53.exit 0
54.

2.配置Realserver脚本.

1.#vi /usr/local/sbin/realserver.sh
2.#!/bin/bash
3.# description: Config realserver lo and apply noarp
4.#Written by :NetSeek http://www.linuxtone.org
5.
6.SNS_VIP=61.164.122.8
7.
8../etc/rc.d/init.d/functions
9.
10.case "$1" in
11.start)
12.ifconfig lo:0 $SNS_VIP netmask 255.255.255.255 broadcast $SNS_VIP
13./sbin/route add -host $SNS_VIP dev lo:0
14.echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
15.echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
16.echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
17.echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
18.sysctl -p >/dev/null 2>&1
19.echo "RealServer Start OK"
20.
21.;;
22.stop)
23.ifconfig lo:0 down
24.route del $SNS_VIP >/dev/null 2>&1
25.echo "0" >/proc/sys/net/ipv4/conf/lo/arp_ignore
26.echo "0" >/proc/sys/net/ipv4/conf/lo/arp_announce
27.echo "0" >/proc/sys/net/ipv4/conf/all/arp_ignore
28.echo "0" >/proc/sys/net/ipv4/conf/all/arp_announce
29.echo "RealServer Stoped"
30.;;
31.*)
32.echo "Usage: $0 {start|stop}"
33.exit 1
34.esac
35.
36.exit 0

或者采用secondary ip address方式配置

# vi /etc/sysctl.conf
1.net.ipv4.conf.lo.arp_ignore = 1
2.net.ipv4.conf.lo.arp_announce = 2
3.net.ipv4.conf.all.arp_ignore = 1
4.net.ipv4.conf.all.arp_announce = 2
5.[code]
6.#sysctl –p
7.#ip addr add 61.164.122.8/32 dev lo
8.#ip add list 查看是否绑定
9.3.启动lvs-dr脚本和realserver启本，在DR上可以查看LVS当前状态:
10.#watch ipvsadm –ln

#p#利用Keepalvied实现负载均衡和和高可用性 1.配置在主负载均衡服务器上配置keepalived.conf

#vi /etc/keepalived/keepalived.conf
1.! Configuration File for keepalived
2.
3.global_defs {
4.notification_email {
5.cnseek@gmail.com
6.}
7.notification_email_from sns-lvs@gmail.com
8.smtp_server 127.0.0.1
9.# smtp_connect_timeout 30
10.router_id LVS_DEVEL
11.}
12.
13.# 20081013 written by :netseek
14.# VIP1
15.vrrp_instance VI_1 {
16.state MASTER#备份服务器上将MASTER改为BACKUP
17.interface eth0
18.virtual_router_id 51
19.priority 100# 备份服务上将100改为99
20.advert_int 1
21.authentication {
22.auth_type PASS
23.auth_pass 1111
24.}
25.virtual_ipaddress {
26.61.164.122.8
27.#(如果有多个VIP，继续换行填写.)
28.}
29.}
30.
31.virtual_server 61.164.122.8 80 {
32.delay_loop 6 #(每隔10秒查询realserver状态)
33.lb_algo wrr #(lvs 算法)
34.lb_kind DR #(Direct Route)
35.persistence_timeout 60#(同一IP的连接60秒内被分配到同一台realserver)
36.protocol TCP#(用TCP协议检查realserver状态)
37.
38.real_server 61.164.122.9 80 {
39.weight 3#(权重)
40.TCP_CHECK {
41.connect_timeout 10#(10秒无响应超时)
42.nb_get_retry 3
43.delay_before_retry 3
44.connect_port 80
45.}
46.}
47.real_server 61.164.122.10 80 {
48.weight 3
49.TCP_CHECK {
50.connect_timeout 10
51.nb_get_retry 3
52.delay_before_retry 3
53.connect_port 80
54.}
55.}
56.}

2.BACKUP服务器同上配置，先安装lvs再按装keepalived,仍后配置/etc/keepalived/keepalived.conf，只需将红色标示的部分改一下即可.

3.停掉lvs_dr.sh演示脚本

vi /etc/rc.local
#/usr/local/sbin/lvs-dr.sh将lvs-dr.sh这个脚本注释掉。
#/usr/local/sbin/lvs-dr.sh stop 停止lvs-dr脚本
#/etc/init.d/keepalived start启动keepalived 服务，keepalived就能利用keepalived.conf 配置文件，实现负载均衡和高可用.

整个LVS负均衡HA方案，由keepalived.conf一个文件即可搞定！

4.查看lvs服务是否正常

#watch ipvsadm –ln
1.IP Virtual Server version 1.2.1 (size=4096)
2.Prot LocalAddressort Scheduler Flags
3.-> RemoteAddressort Forward Weight ActiveConn InActConn
4.TCP61.164.122.8:80 wrr persistent 60
5.-> 61.164.122.10:80Route 3 00
6.-> 61.164.122.9:80Route 3 00
#tail –f /var/log/message监听日志，查看状态，测试LVS负载均衡及高可用性是否有效。

5．停Master服务器的keepalived服务，查看BAKCUP服务器是否能正常接管服务。