操作系统平台：CentOS5.2
软件：LVS+keepalived

LVS+Keepalived 介绍

LVS

LVS是Linux Virtual Server的简写，意即Linux虚拟服务器，是一个虚拟的服务器集群系统。本项目在1998年5月由章文嵩博士成立，是中国国内最早出现的自由软件项目之一。目前有三种IP负载均衡技术（VS/NAT、VS/TUN和VS/DR）；
十种调度算法（rrr|wrr|lc|wlc|lblc|lblcr|dh|sh|sed|nq）。
Keepalvied
Keepalived在这里主要用作RealServer的健康状态检查以及LoadBalance主机和BackUP主机之间failover的实现



IP配置信息:

• LVS-DR-Master          192.168.2.166

• LVS-DR-BACKUP          192.168.2.167

• LVS-DR-VIP             192.168.2.170        

• WEB1-Realserver        192.168.2.171

• WEB2-Realserver        192.168.2.172

• GateWay                192.168.2.253
  安装LVS和Keepalvied软件包
  
  1. 下载相关软件包
  #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
  
  2. 安装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     #做成系统启动服务方便管理.
  四. 配置LVS实现负载均衡
  
   1． LVS-DR，配置LVS脚本实现负载均衡
  
  vi /usr/local/sbin/lvs-dr.sh
  
  #!/bin/bash
  # description: start LVS of DirectorServer
  #Written by :NetSeek
  http://www.linuxtone.org
  GW=192.168.2.253
  
  # website director vip.
  WEB_VIP=192.168.2.170
  WEB_RIP1=192.168.2.171
  WEB_RIP2=192.168.2.172
  . /etc/rc.d/init.d/functions
  
  logger $0 called with $1
  
  case "$1" in
  
  start)
         # Clear all iptables rules.
         /sbin/iptables -F
         # Reset iptables counters.
         /sbin/iptables -Z
         # Clear all ipvsadm rules/services.
         /sbin/ipvsadm -C
  
  #set lvs vip for dr
         /sbin/ipvsadm --set 30 5 60
         /sbin/ifconfig eth0:0 $WEB_VIP broadcast $WEB_VIP netmask 255.255.255.255 up
         /sbin/route add -host $WEB_VIP dev eth0:0
         /sbin/ipvsadm -A -t $WEB_VIP:80 -s wrr -p 3
         /sbin/ipvsadm -a -t $WEB_VIP:80 -r $WEB_RIP1:80 -g -w 1
         /sbin/ipvsadm -a -t $WEB_VIP:80 -r $WEB_RIP2:80 -g -w 1
         touch /var/lock/subsys/ipvsadm >/dev/null 2>&1
  
         # set Arp
         /sbin/arping -I eth0 -c 5 -s $WEB_VIP $GW >/dev/null 2>&1
        ;;
  stop)
         /sbin/ipvsadm -C
         /sbin/ipvsadm -Z
         ifconfig eth0:0 down
         route del $WEB_VIP  >/dev/null 2>&1
         rm -rf /var/lock/subsys/ipvsadm >/dev/null 2>&1
         /sbin/arping -I eth0 -c 5 -s $WEB_VIP $GW
         echo "ipvsadm stoped"
        ;;
  
  status)
  
         if [ ! -e /var/lock/subsys/ipvsadm ];then
                 echo "ipvsadm is stoped"
                 exit 1
         else
                 ipvsadm -ln
                 echo "..........ipvsadm is OK."
         fi
       ;;
  
  *)
         echo "Usage: $0 {start|stop|status}"
         exit 1
  esac
  
  exit 0
  2． 配置Realserver脚本.
  
  #!/bin/bash
  # Written by NetSeek
  # description: Config realserver lo and apply noarp
  WEB_VIP=192.168.2.170
  
  . /etc/rc.d/init.d/functions
  
  case "$1" in
  start)
        ifconfig lo:0 $WEB_VIP netmask 255.255.255.255 broadcast $WEB_VIP
        /sbin/route add -host $WEB_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 $WEB_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"
        ;;
  status)
         # Status of LVS-DR real server.
         islothere=`/sbin/ifconfig lo:0 | grep $WEB_VIP`
         isrothere=`netstat -rn | grep "lo:0" | grep $web_VIP`
         if [ ! "$islothere" -o ! "isrothere" ];then
             # Either the route or the lo:0 device
             # not found.
             echo "LVS-DR real server Stopped."
         else
             echo "LVS-DR Running."
         fi
  ;;
  *)
         # Invalid entry.
         echo "$0: Usage: $0 {start|status|stop}"
         exit 1
  ;;
  esac
  exit 0
  
  附上realserver机上的/etc/sysctl.conf：
  
  # Kernel sysctl configuration file for Red Hat Linux
  #
  # For binary values, 0 is disabled, 1 is enabled.  See sysctl(8) and
  # sysctl.conf(5) for more details.
  # Controls IP packet forwarding
  net.ipv4.ip_forward = 1
  # Controls source route verification
  net.ipv4.conf.default.rp_filter = 1
  # Do not accept source routing
  net.ipv4.conf.default.accept_source_route = 0
  # Controls the System Request debugging functionality of the kernel
  kernel.sysrq = 0
  # Controls whether core dumps will append the PID to the core filename.
  # Useful for debugging multi-threaded applications.
  kernel.core_uses_pid = 1
  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
  或者采用secondary ip address方式配置
  # vi /etc/sysctl.conf
  
  添加以下内容如上所示：
  
  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 查看是否绑定
  3. 启动lvs-dr脚本和realserver启本，在DR上可以查看LVS当前状态:
  #watch ipvsadm –ln
  
  五．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 (主调度器)
  ! Configuration File for keepalived
  global_defs {
    notification_email {
  
  acassen@firewall.loc
  
  failover@firewall.loc
  
  sysadmin@firewall.loc
    }
    notification_email_from
  Alexandre.Cassen@firewall.loc
    smtp_server 127.0.0.1
    smtp_connect_timeout 30
    router_id LVS_DEVEL
  }
  vrrp_instance VI_1 {
     state MASTER
     interface eth0
     virtual_router_id 51
     priority 100
     advert_int 1
     authentication {
         auth_type PASS
         auth_pass 1111
     }
     virtual_ipaddress {
         192.168.2.170
     }
  }
  virtual_server 192.168.2.170 80 {
     delay_loop 6
     lb_algo wrr
     lb_kind DR
     persistence_timeout 60
     protocol TCP
  
     real_server 192.168.2.171 80 {
         weight 3            
         TCP_CHECK {
         connect_timeout 10  
         nb_get_retry 3
         delay_before_retry 3
         connect_port 80
  }
     }
     real_server 192.168.2.172 80 {
         weight 3
         TCP_CHECK {
         connect_timeout 10
         nb_get_retry 3
         delay_before_retry 3
         connect_port 80
         }
      }
  }
  
  在备用调度器上：
  #vi /etc/keepalived/keepalived.conf (备用调度器)
  ! Configuration File for keepalived
  global_defs {
    notification_email {
  
  acassen@firewall.loc
  
  failover@firewall.loc
  
  sysadmin@firewall.loc
    }
    notification_email_from
  Alexandre.Cassen@firewall.loc
    smtp_server 127.0.0.1
    smtp_connect_timeout 30
    router_id LVS_DEVEL
  }
  vrrp_instance VI_1 {
     state BACKUP
     interface eth0
     virtual_router_id 51
     priority 99
     advert_int 1
     authentication {
         auth_type PASS
         auth_pass 1111
     }
     virtual_ipaddress {
         192.168.2.170
     }
  }
  virtual_server 192.168.2.170 80 {
     delay_loop 6
     lb_algo wrr
     lb_kind DR
     persistence_timeout 60
     protocol TCP
  
     real_server 192.168.2.171 80 {
         weight 3            
         TCP_CHECK {
         connect_timeout 10  
         nb_get_retry 3
         delay_before_retry 3
         connect_port 80
  }
     }
     real_server 192.168.2.172 80 {
         weight 3
         TCP_CHECK {
         connect_timeout 10
         nb_get_retry 3
         delay_before_retry 3
         connect_port 80
         }
      }
  }
  
  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. 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.
  4. 查看lvs服务是否正常
  
  #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
  复制代码
  #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。
  四．相关参考
  1．LVS 基础知识汇总
  LVS的算法介绍            
  http://www.linuxtone.org/viewthread.php?tid=69
  学习LVS的三种转发模式    
  http://www.linuxtone.org/viewthread.php?tid=77
  LVS中的IP负载均衡技术    
  http://www.linuxtone.org/viewthread.php?tid=68
  更多的请到
  http://www.linuxtone.org
  负载均衡版查看
  Keepalived 相关参考资料。
  
  http://www.keepalived.org/documentation.html