相關概念

一、準備工作
1. 伺服器、作業系統（當前CentOS6.6 x86_64）、網路環境（服務期間網路互通） ；

# 作業系統：CentOS6.6 x86_64# 伺服器 （LVS主備各1臺，WEB伺服器3臺，圖片伺服器2臺）WEBServer負載虛擬IP：192.168.0.20IMGServer負載虛擬IP：192.168.0.30
LVS主：192.168.0.11
LVS備：192.168.0.12WebServer1：192.168.0.21WebServer2：192.168.0.22WebServer3：192.168.0.23IMGServer1：192.168.0.31IMGServer2
 
：192.168.0.32

2. 關閉SELinux(改完需重啟伺服器)；

# 關閉SELinux
sed -i 's#^SELINUX=.*#SELINUX=disabled#'/etc/sysconfig/selinux   
# 重啟伺服器
reboot  

3. Iptables開啟需要埠，如80；

# Iptables 開啟相應埠
iptables -A INPUT -p tcp -s 0/0--dport 80-j ACCEPT   
iptables -A OUTPUT  -p tcp --sport 80-m state --state ESTABLISHED -j ACCEPT  

二、LVS主機安裝Keepalived，ipvsadm

yum -y install wget popt popt-devel popt-static libnl libnl-devel kernel-devel;  
ln -s /usr/src/kernels/$(uname -r)/ /usr/src/linux;

2. 安裝 Keepalived，ipvsadm（YUM安裝或TarBall安裝）

# YUM安裝 Keepalived，ipvsadm
yum -y install  keepalived ipvsadm;# TarBall安裝Keepalived
wget http://www.keepalived.org/software/keepalived-1.2.15.tar.gz;
 

tar xvf keepalived-1.2.15.tar.gz -C /usr/local/src/;
cd /usr/local/src/keepalived-1.2.15/;./configure \
--bindir=/usr/bin \
--sbindir=/usr/sbin \
--sysconf=/etc \
--with-kernel-dir=/usr/src/kernels/$(uname -r)/;
make;
make install;# TarBall安裝ipvsadm
wget http://www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.26.tar.gz;  
tar xvf ipvsadm-1.26.tar.gz -C /usr/local/src/;
cd /usr/local/src/ipvsadm-1.26/;
make;
make install;

3. 建立ipvsadm配置檔案，啟動並加入開機啟動

/etc/init.d/ipvsadm save;/etc/init.d/ipvsadm start;
chkconfig ipvsadm on;

4. 配置並啟動keepalived

# 備份keepalived配置檔案
cd /etc/keepalived/;[-f "keepalived.conf"-a !-f "keepalived.conf.default"]&& mv /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.default;[-f "keepalived.conf"]&& mv keepalived.conf keepalived.conf.$(date +%F_%T);# 建立 Keepalived 配置檔案（需先修改 virtual_ipaddress，virtual_server，real_server 配置的IP）
cat >>/etc/keepalived/keepalived.conf <<KEEPALIVED
!ConfigurationFilefor keepalived

global_defs {
    notification_email {
        [email protected].cn
    }
    notification_email_from [email protected].com
    smtp_server [email protected].com
    smtp_connect_timeout 30
    router_id LVS_1
}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 60
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass MrUse}
    virtual_ipaddress {192.168.0.20192.168.0.30}}

virtual_server 192.168.0.2180{
    delay_loop 3
    lb_algo rr
    lb_kind DR
    persistence_timeout 3
    protocol TCP

    real_server 192.168.0.2280{
        weight 3
        TCP_CHECK {
            connect_timeout 10
            nb_get_retry 3
            delay_before_retry 3
            connect_port 80}}

    real_server 192.168.0.2380{
        weight 3
        TCP_CHECK {
            connect_timeout 10
            nb_get_retry 3
            delay_before_retry 3
            connect_port 80}}}

virtual_server 172.16.100.13080{
    delay_loop 3
    lb_algo rr
    lb_kind DR
    persistence_timeout 3
    protocol TCP

    real_server 192.168.0.3180{
        weight 3
        TCP_CHECK {
            connect_timeout 10
            nb_get_retry 3
            delay_before_retry 3
            connect_port 80}}

    real_server 192.168.0.3280{
        weight 3
        TCP_CHECK {
            connect_timeout 10
            nb_get_retry 3
            delay_before_retry 3
            connect_port 80}}}
KEEPALIVED

# 啟動Keepalived並加入開機啟動/etc/init.d/keepalived restart;
chkconfig keepalived on;

5. 記錄Keepalived日誌

# 註釋Keepalived預設配置
grep ^KEEPALIVED_OPTIONS /etc/sysconfig/keepalived && sed -i 's#^KEEPALIVED_OPTIONS#\#KEEPALIVED_OPTIONS#g'/etc/sysconfig/keepalived;# 更新keepalived配置
echo 'KEEPALIVED_OPTIONS="-D -d -S 0"'>>/etc/sysconfig/keepalived;/etc/init.d/keepalived restart
grep "# CmsTop Keepalived"/etc/rsyslog.conf||cat >>/etc/rsyslog.conf <<SYSLOG
# CmsTop Keepalived $(date +%F)# keepalived -D -d -S 0
local0.*/var/log/keepalived.log
SYSLOG
/etc/init.d/rsyslog restart

6. 為真實伺服器 WebServer, IMGServe建立配置啟動指令碼（需修改IP地址）

[-f "/etc/init.d/lvsr"]&& mv /etc/init.d/lvsr /etc/init.d/lvsr.$(date +%F_%T)
cat >>/etc/init.d/lvsr <<LVSR
#!/bin/bash

SNS_VIP=172.16.100.120/etc/rc.d/init.d/functions

start(){/sbin/ifconfig lo:0 \$SNS_VIP netmask 255.255.255.255 broadcast \$SNS_VIP up
    /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/null2>&1
    echo "LVS RealServer Start OK"}
stop(){/sbin/ifconfig lo:0 down
    /sbin/route del \$SNS_VIP >/dev/null2>&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 "LVS RealServer Stoped"}case"\$1"in
    start)
        start;;;
    stop)
        stop;;;
    restart)
        stop;
        start;;;
    status)/sbin/ifconfig|tail -5;;*)
        echo "Usage: \$0 {start|stop|restart|status}"exit1esacexit0
LVSR

# 修改依賴檔案及啟動指令碼許可權並啟動
chmod +x /etc/init.d/lvsr;
chmod +x /etc/rc.d/init.d/functions;/etc/init.d/lvsr start

# 加入開機啟動
grep ^/etc/init.d/lvsr /etc/rc.local|| echo '/etc/init.d/lvsr start'>>/etc/rc.local

三、檢視狀態、測試排錯
1. 重啟Keepalived，在LVS伺服器上檢視狀態

/etc/init.d/keepalived restart;/etc/init.d/ipvsadm status;

2. 測試排查思路

# 檢視配置檔案，檢視ip# 檢視Iptables是否開啟相應埠# 檢視網路，伺服器間及與虛擬IP是否可以通訊# 檢視Keepalived，ipvsadm是否正常啟動# 檢視錯誤日誌