linux使用lvs和keepalived構(gòu)建高可用網(wǎng)絡(luò)負(fù)載均衡

1、Lvs和keepalived構(gòu)建高可用網(wǎng)絡(luò)負(fù)載均衡環(huán)境使用lvs和keepalived構(gòu)建高可用網(wǎng)絡(luò)負(fù)載均衡耿紅杰， 2008-12-11說明： 該方案可以作為lvsheartbeat構(gòu)建網(wǎng)絡(luò)負(fù)載均衡的替代方案。LVS簡介Lvs（linux virtual server）是唯一國人參與內(nèi)核設(shè)計(jì)和實(shí)現(xiàn)的linux開源項(xiàng)目，提供基于IP的網(wǎng)絡(luò)負(fù)載均衡技術(shù)。目前提供VS/NAT、VS/TUN、VS/DR共計(jì)3種技術(shù)，8種調(diào)度算法（也看到有人又?jǐn)U充了一些調(diào)度算法，沒有研究過）；應(yīng)用較多的是VS/DR,VS/NAT；本文介紹VS/DR。關(guān)于lvs的結(jié)構(gòu)和原理，請參考lvs的官方文檔。Keepalived

2、簡介Keepalived的作用主要是進(jìn)行realserver的健康檢查；采取至少2臺主機(jī)的方式提供一個(gè)高可用的環(huán)境（failover）保證lvs能夠持續(xù)運(yùn)行。Keepalived采用路由器（router）的概念，實(shí)現(xiàn)了VRRP（Virtual Router Redundancy Protocol），定義1個(gè)虛擬router，定義router的master、backup狀態(tài)和priority，采用多播地址（8）進(jìn)行通信，提供高可用。虛擬routerID相同的router為一個(gè)組，由master廣播數(shù)據(jù)，在backup收不到master的廣播數(shù)據(jù)時(shí)，提升自己為master。系統(tǒng)可

3、以定義多個(gè)vrrp實(shí)例。詳細(xì)內(nèi)容請參考keepalived的用戶手冊和vrrp協(xié)議。高可用環(huán)境LvsMasterLvsBackup缺省情況由A負(fù)責(zé)lvs進(jìn)行負(fù)載均衡的調(diào)度； 通過vrrp協(xié)議由8多播地址進(jìn)行通信，若A故障第 1 頁 共 4 頁Lvs和keepalived構(gòu)建高可用網(wǎng)絡(luò)負(fù)載均衡環(huán)境時(shí)，則B會接管服務(wù)升級為master狀態(tài)；從而保證業(yè)務(wù)的持續(xù)運(yùn)行。實(shí)施步驟在2臺主機(jī)上安裝lvs和keepalived，在realserver上僅需要配置一下虛擬ip。 # ln s /usr/src/kernels/2.6.9-55.EL-smp-i686/ /usr/src/lin

4、ux1. 安裝lvs# make && make install2. 安裝keepalived#./configure && make && make install#cp /usr/local/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/#cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/#mkdir /etc/keepalived#cp /usr/local/etc/keepalived/keepalived.conf /etc/keepal

5、ived/#cp /usr/local/sbin/keepalived /usr/sbin/#service keepalived start|stop #做成系統(tǒng)啟動(dòng)服務(wù)方便管理.3. 配置keepalived示例如下，詳細(xì)的配置請參考用戶手冊。# vi /etc/keepalived/keepalived.conf! Configuration File for keepalivedglobal_defs notification_email acassennotification_email_from Alexandre.Cassenfirewall.locsmtp_server 192

6、.168.200.1smtp_connect_timeout 30router_id LVS_DEVELvrrp_instance VI_1 state MASTER # 備機(jī)為backupinterface eth0virtual_router_id 51 # 主機(jī)備機(jī)相同priority 150 # 備機(jī)可以設(shè)置為100，表明優(yōu)先級低advert_int 1virtual_ipaddress 5 # 虛擬IP，由keepavlied啟動(dòng)在系統(tǒng)的IP地址列表中 virtual_server 5 80 delay_loop 6lb_algo rrlb

7、_kind DRprotocol TCPreal_server 02 80 weight 1TCP_CHECK connect_timeout 3nb_get_retry 3delay_before_retry 3connect_port 80第 2 頁 共 4 頁Lvs和keepalived構(gòu)建高可用網(wǎng)絡(luò)負(fù)載均衡環(huán)境real_server 7 80 weight 3TCP_CHECK connect_timeout 3nb_get_retry 3delay_before_retry 3connect_port 804. 啟動(dòng)keepalived#

8、service keepalived start5. realserver 配置根據(jù)VS/DR的原理，在realserver的lo接口上配置虛擬ip地址。 # vi /etc/init.d/realserver.sh#!/bin/bash# description: Config realserver lo and apply noarpSNS_VIP=5. /etc/rc.d/init.d/functionscase "$1" instart)ifconfig lo:0 $SNS_VIP netmask 55 broadca

9、st $SNS_VIP /sbin/route add -host $SNS_VIP dev lo:0echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignoreecho "2" >/proc/sys/net/ipv4/conf/lo/arp_announceecho "1" >/proc/sys/net/ipv4/conf/all/arp_ignoreecho "2" >/proc/sys/net/ipv4/conf/all/arp_announcesys

10、ctl -p >/dev/null 2>&1echo "RealServer Start OK"stop)ifconfig lo:0 downroute del $SNS_VIP >/dev/null 2>&1echo "0" >/proc/sys/net/ipv4/conf/lo/arp_ignoreecho "0" >/proc/sys/net/ipv4/conf/lo/arp_announceecho "0" >/proc/sys/net/ipv4/c

11、onf/all/arp_ignoreecho "0" >/proc/sys/net/ipv4/conf/all/arp_announceecho "RealServer Stoped"*)echo "Usage: $0 start|stop"exit 1esacexit 06. 系統(tǒng)狀態(tài)檢查Ø 日志檢查# vi /var/log/messagesØ 網(wǎng)絡(luò)負(fù)載均衡檢查# ipvsadmIP Virtual Server version 1.2.0 (size=4096)Prot LocalAddress:Por

12、t Scheduler Flags-> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 5:http rr-> 7:http Route 3 0 0-> 02:http Route 1 0 0Ø Ip地址檢查# ip addr list第 3 頁 共 4 頁Lvs和keepalived構(gòu)建高可用網(wǎng)絡(luò)負(fù)載均衡環(huán)境2: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_f

13、ast qlen 1000link/ether 00:11:43:ad:a1:2c brd ff:ff:ff:ff:ff:ffinet 5/24 brd 55 scope global eth0inet 5/32 scope global eth07. 負(fù)載均衡測試8. 注意事項(xiàng)Realserver的檢查機(jī)制需要進(jìn)行大量測試。Vip的管理機(jī)制：我在測試中由于本機(jī)同時(shí)是realserver，所以也設(shè)置了lo的虛擬IP地址，結(jié)果發(fā)現(xiàn)該主機(jī)一直在進(jìn)行網(wǎng)絡(luò)分發(fā)，從ipvsadm可以看到realserver；個(gè)人理解這種情況下是由于ipvsadm的數(shù)據(jù)在不