LVS+keepalived負載均衡 ？？待續

背景:
        隨着你的網站業務量的增加你網站的服務器壓力愈來愈大？須要負載均衡方案！商業的硬件如F5又太貴，大家又是創業型互聯公司如何有效節約成本，節省沒必要要的浪費？同時實現商業硬件同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？答案是確定的！有！咱們利用 LVS+Keepalived基於完整開源軟件的架構能夠爲你提供一個負載均衡及高可用的服務器。

LVS+Keepalived 介紹
LVS
        LVS是Linux Virtual Server的簡寫，意即Linux虛擬服務器，是一個虛擬的服務器集羣系統。本項目在1998年5月由章文嵩博士成立，是中國國內最先出現的自由軟件項目之一.目前有三種IP負載均衡技術（VS/NAT、VS/TUN和VS/DR）；
八種調度算法（rr,wrr,lc,wlc,lblc,lblcr,dh,sh）。

Keepalvied
        Keepalived在這裏主要用做RealServer的健康狀態檢查以及LoadBalance主機和BackUP主機之間failover的實現
二. 網站負載均衡構架圖


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 
三. 安裝LVS和Keepalvied軟件包
1. 下載相關軟件包

#mkdir /usr/local/src/lvs
#cd /usr/local/src/lvs
#wget #wget http://www.keepalived.org/software/keepalived-1.1.15.tar.gz

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     #作成系統啓動服務方便管理.

四. 配置LVS實現負載均衡
  1． LVS-DR，配置LVS腳本實現負載均衡

      #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
           ifconfig eth0:1 down
           route del $SNS_VIP
           route del $SS_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

2． 配置Realserver腳本.

#vi /usr/local/sbin/realserver.sh
        #!/bin/bash
        # description: Config realserver lo and apply noarp 
        #Written by :NetSeek 
 
        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

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. 啓動lvs-dr腳本和realserver啓本，在DR上能夠查看LVS當前狀態:

#watch ipvsadm –ln

五．利用Keepalvied實現負載均衡和和高可用性
  1.配置在主負載均衡服務器上配置keepalived.conf

#vi /etc/keepalived/keepalived.conf

! Configuration File for keepalived
global_defs {
   notification_email {
         cnseek@gmail.com
   }
   notification_email_from sns-lvs@gmail.com
   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             #備份服務器上將MASTER改成BACKUP   
    interface eth0
    virtual_router_id 51
    priority 100    # 備份服務上將100改成99
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        61.164.122.8   
        #(若是有多個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 算法)
    lb_kind DR                  #(Direct Route)
    persistence_timeout 60        #(同一IP的鏈接60秒內被分配到同一臺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
        }
     }
}

2. BACKUP服務器同上配置，先安裝lvs再按裝keepalived,仍後配置/etc/keepalived/keepalived.conf，只需將紅色標示的部分改一下便可.
3.

vi /etc/rc.local
#/usr/local/sbin/lvs-dr.sh  將lvs-dr.sh這個腳本註釋掉。步
#/usr/local/sbin/lvs-dr.sh stop 中止lvs-dr腳本
#/etc/init.d/keepalived start  啓動keepalived 服務，keepalived就能利用

keepalived.conf 配置文件，實現負載均衡和高可用.

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

#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服務器的keepalived服務，查看BAKCUP服務器是否能正常接管服務。
四．相關參考
  1．LVS 基礎知識彙總
LVS的算法介紹               http://www.linuxtone.org/viewthread.php?tid=69
學習LVS的三種轉發模式       http://www.linuxtone.org/viewthread.php?tid=77
LVS中的IP負載均衡技術       http://www.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