利用LVS+Keepalived 實現高性能高可用負載均衡伺服器
背景:
隨著你的網站業務量的增長你網站的伺服器壓力越來越大？需要負載均衡方案！商業的硬體如F5又太貴，你們又是創業型互聯公司如何有效節約成本，節省不必要的浪費？同時實現商業硬體一樣的高性能高可用的功能？有什麼好的負載均衡可伸張可擴展的方案嗎？答案是肯定的！有！我們利用LVS+Keepalived基於完整開源軟體的架構可以為你提供一個負載均衡及高可用的伺服器。
LVS+Keepalived 介紹
LVS
LVS是Linux Virtual Server的簡寫，意即Linux虛擬伺服器，是一個虛擬的伺服器集群系統。本項目在1998年5月由章文嵩博士成立，是中國國內最早出現的自由軟體項目之一。目前有三種IP負載均衡技術（VS/NAT、VS/TUN和VS/DR）；
十種調度演演算法（rrr|wrr|lc|wlc|lblc|lblcr|dh|sh|sed|nq）。
Keepalvied
Keepalived在這裡主要用作RealServer的健康狀態檢查以及LoadBalance主機和BackUP主機之間failover的實現
二. 網站負載均衡拓樸圖
IP信息列表：
名稱 IP
LVS-DR-Master 61.164.122.6
•LVS-DR-BACKUP 61.164.122.7
•LVS-DR-VIP 61.164.122.8
•WEB1-Realserver 61.164.122.9
•WEB2-Realserver 61.164.122.10
•GateWay 61.164.122.1
複製代碼三. 安裝LVS和Keepalvied軟體包
1. 下載相關軟體包
#mkdir /usr/local/src/lvs
• #cd /usr/local/src/lvs
• #wget http://www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.24.tar.gz
• #wget http://www.keepalived.org/software/keepalived-1.1.15.tar.gz
複製代碼2. 安裝LVS和Keepalived
#lsmod |grep ip_vs• #uname -r
• 2.6.18-53.el5PAE
• #ln -s /usr/src/kernels/2.6.18-53.el5PAE-i686/ /usr/src/linux
•
• #tar zxvf ipvsadm-1.24.tar.gz
• #cd ipvsadm-1.24
• #make && make install
• #find / -name ipvsadm # 查看ipvsadm的位置
•
• #tar zxvf keepalived-1.1.15.tar.gz
• #cd keepalived-1.1.15
• #./configure && make && make install
• #find / -name keepalived # 查看keepalived位置
•
• #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/keepalived/
• #cp /usr/local/sbin/keepalived /usr/sbin/
• #service keepalived start|stop #做成系統啟動服務方便管理.
複製代碼四. 配置LVS實現負載均衡
1． LVS-DR，配置LVS腳本實現負載均衡
注: 此腳本在於演示方便大家理解lvs,在keepalived方案中不要啟動此腳本，所以看後面有注掉，很多朋友對此有問題。關於LVS的keepalvied的HA方案，完全由keepalived.conf一個文件搞定，特此聲明！ #vi /usr/local/sbin/lvs-dr.sh
• #!/bin/bash
• # description: start LVS of DirectorServer
• #Written by :NetSeek http://www.linuxtone.org
•
• GW=61.164.122.1
• # website director vip.
• SNS_VIP=61.164.122.8
• SNS_RIP1=61.164.122.9
• SNS_RIP2=61.164.122.10
•
• ./etc/rc.d/init.d/functions
•
• logger $0 called with $1
•
• case "$1" in
•
• start)
• # set squid vip
• /sbin/ipvsadm --set 30 5 60
• /sbin/ifconfig eth0:0 $SNS_VIP broadcast $SNS_VIP netmask 255.255.255.255 broadcast $SNS_VIP up
• /sbin/route add -host $SNS_VIP dev eth0:0
• /sbin/ipvsadm -A -t $SNS_VIP:80 -s wrr -p 3
• /sbin/ipvsadm -a -t $SNS_VIP:80 -r $SNS_RIP1:80 -g -w 1
• /sbin/ipvsadm -a -t $SNS_VIP:80 -r $SNS_RIP2:80 -g -w 1
• touch /var/lock/subsys/ipvsadm >/dev/null 2>&1
•
• ;;
•stop)
• /sbin/ipvsadm -C
• /sbin/ipvsadm -Z
• ifconfig eth0:0 down
• route del $SNS_VIP
• rm -rf /var/lock/subsys/ipvsadm >/dev/null 2>&1
• echo "ipvsadm stoped"
• ;;
•
•status)
•
• if [ ! -e /var/lock/subsys/ipvsadm ];then
• echo "ipvsadm stoped"
• exit 1
• else
• echo "ipvsadm OK"
• fi
• ;;
•
•*)
• echo "Usage: $0 {start|stop|status}"
• exit 1
•esac
•
•exit 0
• 複製代碼2． 配置Realserver腳本. #vi /usr/local/sbin/realserver.sh
• #!/bin/bash
• # description: Config realserver lo and apply noarp
• #Written by :NetSeek http://www.linuxtone.org
•
• SNS_VIP=61.164.122.8
•
• . /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
• 複製代碼或者採用secondary ip address方式配置# vi /etc/sysctl.conf
net.ipv4.conf.lo.arp_ignore = 1
• net.ipv4.conf.lo.arp_announce = 2
• net.ipv4.conf.all.arp_ignore = 1
• net.ipv4.conf.all.arp_announce = 2
•
• #sysctl ?p
• #ip addr add 61.164.122.8/32 dev lo
• #ip add list 查看是否綁定
• 3. 啟動lvs-dr腳本和realserver啟本，在DR上可以查看LVS當前狀態:
• #watch ipvsadm ?ln複製代碼五．利用Keepalvied實現負載均衡和和高可用性
1.配置在主負載均衡伺服器上配置keepalived.conf#vi /etc/keepalived/keepalived.conf
! Configuration File for keepalived
•
•global_defs {
• notification_email {
•
[email protected] • }
• notification_email_from
[email protected] • smtp_server 127.0.0.1
• # smtp_connect_timeout 30
• router_id LVS_DEVEL
•}
•
•# 20081013 written by :netseek
•# VIP1
•vrrp_instance VI_1 {
• state MASTER #備份伺服器上將MASTER改為BACKUP
• interface eth0
• virtual_router_id 51
• priority 100 # 備份服務上將100改為99
• advert_int 1
• authentication {
• auth_type PASS
• auth_pass 1111
• }
• virtual_ipaddress {
• 61.164.122.8
• #(如果有多個VIP，繼續換行填寫.)
• }
•}
•
•virtual_server 61.164.122.8 80 {
• delay_loop 6 #(每隔10秒查詢realserver狀態)
• lb_algo wrr #(lvs 演演算法)
• lb_kind DR #(Direct Route)
• persistence_timeout 60 #(同一IP的連接60秒內被分配到同一台realserver)
• protocol TCP #(用TCP協議檢查realserver狀態)
•
• real_server 61.164.122.9 80 {
• weight 3 #(權重)
• TCP_CHECK {
• connect_timeout 10 #(10秒無響應超時)
• nb_get_retry 3
• delay_before_retry 3
• connect_port 80
• }
• }
• real_server 61.164.122.10 80 {
• weight 3
• TCP_CHECK {
• connect_timeout 10
• nb_get_retry 3
• delay_before_retry 3
• connect_port 80
• }
• }
•}
• 複製代碼2. BACKUP伺服器同上配置，先安裝lvs再按裝keepalived,仍后配置/etc/keepalived/keepalived.conf，只需將紅色標示的部分改一下即可.
3. 停掉lvs_dr.sh演示腳本
vi /etc/rc.local
#/usr/local/sbin/lvs-dr.sh 將lvs-dr.sh這個腳本註釋掉。
#/usr/local/sbin/lvs-dr.sh stop 停止lvs-dr腳本
#/etc/init.d/keepalived start 啟動keepalived 服務，keepalived就能利用keepalived.conf 配置文件，實現負載均衡和高可用.
整個LVS負均衡HA方案，由keepalived.conf一個文件即可搞定！
4. 查看lvs服務是否正常 #watch ipvsadm ?ln
IP Virtual Server version 1.2.1 (size=4096)
•Prot LocalAddressort Scheduler Flags
• -> RemoteAddressort Forward Weight ActiveConn InActConn
•TCP 61.164.122.8:80 wrr persistent 60
• -> 61.164.122.10:80 Route 3 0 0
• -> 61.164.122.9:80 Route 3 0 0複製代碼#tail ?f /var/log/message 監聽日誌，查看狀態，測試LVS負載均衡及高可用性是否有效。
5．停Master伺服器的keepalived服務，查看BAKCUP伺服器是否能正常接管服務。
四．相關參考
1．LVS 基礎知識匯總
LVS的演演算法介紹 http://bbs.linuxtone.org/viewthread.php?tid=69
學習LVS的三種轉發模式 http://bbs.linuxtone.org/viewthread.php?tid=77
LVS中的IP負載均衡技術 http://bbs.linuxtone.org/viewthread.php?tid=68
更多的請到http://www.linuxtone.org 負載均衡版查看
Keepalived 相關參考資料。
http://www.keepalived.org/documentation.html
提供DOC文檔下載:
PDF下載： http://docs.linuxtone.org/ebooks/load%20balance/lvs/
