說明

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。本專案在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專案之一。

目前有三種IP負載均衡技術（VS/NAT、VS/TUN和VS/DR）；十種排程演算法（rr|wrr|lc|wlc|lblc|lblcr|dh|sh|sed|nq）。

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。

LVS+Keepalived能實現的功能：利用LVS控制器主備模式避免單點故障以及自動刪除故障WEB伺服器結點並當它恢復後再自動新增到群集中。

系統環境

作業系統：CentOS 6.5 Kernel 2.6.32-431 el6.x86_64

Keepalived版本：Keepalived for Linux - 

Ipvsadm版本：IP Virtual Server version 1.2.1 

整體架構

4臺伺服器，Lvs Master和Lvs Backup作為負載均衡伺服器實現雙機互備，RealServer兩臺實現服務負載均衡。

軟體安裝

keepalived安裝參照：http://blog.csdn.net/torycatkin/article/details/37917615 Ipvsadm安裝：

yum install ipvsadm
 

檢視安裝結果：

[[email protected] soft_installer]# ipvsadm
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn

說明：keepalived和ipvsadm需要在lvs master和lvs backup上安裝，realserver不需要安裝任何軟體。

配置檔案

LVS Master配置：/etc/keepalived/keepalived.conf

global_defs {
   router_id LVS_DEVEL
}


vrrp_instance VI_1 {
    state MASTER
    interface eth0
    garp_master_delay 10
    smtp_alert
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.254
    }
}

virtual_server 192.168.1.254 80 {
    delay_loop 6
    lb_algo wlc
    lb_kind DR
    #persistence_timeout 20
    protocol TCP

    real_server 192.168.1.203 80 {
        weight 100
        TCP_CHECK {
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
            connect_port 80
        }
    }
    real_server 192.168.1.204 80 {
        weight 100
        TCP_CHECK {
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
            connect_port 80
        }
    }
}
 

LVS Backup配置：/etc/keepalived/keepalived.conf

global_defs {
   router_id LVS_DEVEL
}


vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    garp_master_delay 10
    smtp_alert
    virtual_router_id 51
    priority 80
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.254
    }
}

virtual_server 192.168.1.254 80 {
    delay_loop 6
    lb_algo wlc
    lb_kind DR
    #persistence_timeout 20
    protocol TCP

    real_server 192.168.1.203 80 {
        weight 100
        TCP_CHECK {
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
            connect_port 80
        }
    }
    real_server 192.168.1.204 80 {
        weight 100
        TCP_CHECK {
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
            connect_port 80
        }
    }
}

Realserver建立指令碼並執行：/usr/local/bin/lvs_real

#!/bin/bash
#description : start realserver
VIP=192.168.1.254
/etc/rc.d/init.d/functions

case "$1" in
start)
echo " start LVS of REALServer"
/sbin/ifconfig lo:0 $VIP broadcast $VIP netmask 255.255.255.255 up
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
;;
stop)
/sbin/ifconfig lo:0 down
echo "close LVS Directorserver"
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 "Usage: $0 {start|stop}"
exit 1
esac

#賦予執行許可權並啟動
chmod +x /usr/local/bin/lvs_real
/usr/local/bin/lvs_real start