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。
LVS是Linux Virtual Server的简称，也就是Linux虚拟服务器, 是一个由章文嵩博士发起的自由软件项目，它的官方站点是www.linuxvirtualserver.org。现在LVS已经是 Linux标准内核的一部分，在Linux2.4内核以前，使用LVS时必须要重新编译内核以支持LVS功能模块，但是从Linux2.4内核以后，已经完全内置了LVS的各个功能模块，无需给内核打任何补丁，可以直接使用LVS提供的各种功能。
使用LVS技术要达到的目标是：通过LVS提供的负载均衡技术和Linux操作系统实现一个高性能、高可用的服务器群集，它具有良好可靠性、可扩展性和可操作性。从而以低廉的成本实现最优的服务性能。
使用LVS架设的服务器集群系统有三个部分组成：最前端的负载均衡层，用Load Balancer表示，中间的服务器群组层，用Server Array表示，最底端的数据共享存储层，用Shared Storage表示，在用户看来，所有的内部应用都是透明的，用户只是在使用一个虚拟服务器提供的高性能服务。
接下来开始部署配置LVS主从：
免责声明：小伙伴在上生产环境前先测试有没有问题哈！！！
本次试验共计使用4台虚拟机，都是centos6.3.
192.168.146.164
192.168.146.160
192.168.146.162
192.168.146.163
具体实验环境配置如下：
192.168.146.101 LVS_VIP
192.168.146.164 LVS_MASTER
192.168.146.160 LVS_SALVE
192.168.146.162 WEB1
192.168.146.163 WEB2
192.168.146.164 LVS_MASTER：
安装IPVSADM：
[root@localhost ~]# yum -y install ipvsadm
为了测试方便，暂时关闭防火墙：
[root@localhost ~]# service iptables stop
安装KeepAlived：
[root@localhost ~]# cd /usr/src
[root@localhost src]# yum -y install openssl-devel
root@localhost src]# wget http://www.keepalived.org/software/keepalived-1.2.7.tar.gz
[root@localhost src]# wget http://mirror.centos.org/centos/6/os/x86_64/Packages/popt-static-1.13-7.el6.x86_64.rpm
[root@localhost src]# yum -y install popt-static-1.13-7.el6.x86_64.rpm
[root@localhost src]# yum -y install kernel-devel make gcc openssl-devel libnl* popt*
[root@localhost src]# ln -s /usr/src/kernels/2.6.32-220.13.1.el6.x86_64/ /usr/src/linux
[root@localhost src]# tar zxvf keepalived-1.2.7.tar.gz
[root@localhost src]# cd keepalived-1.2.7
[root@localhost keepalived-1.2.7]# ./configure --with-kernel-dir=/usr/src/kernels/2.6.32-358.2.1.el6.x86_64/
[root@localhost keepalived-1.2.7]# make && make install
[root@localhost keepalived-1.2.7]# cp /usr/local/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
[root@localhost keepalived-1.2.7]# cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
[root@localhost keepalived-1.2.7]# mkdir /etc/keepalived
[root@localhost keepalived-1.2.7]# cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/
[root@localhost keepalived-1.2.7]# cp /usr/local/sbin/keepalived /usr/sbin/
KeepAlived安装完毕，然后进行配置。
打开IP Forward 功能（LVS现有三种负载均衡规则都需要打开此功能，如果不打开此功能，下面的配置配得再好都无济于事。）
打开后修改里面“net.ipv4.ip_forward = 1”
[root@localhost keepalived-1.2.7]# cat /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
执行如下命令使设置立即生效：
[root@localhost keepalived-1.2.7]# sysctl -p
net.ipv4.ip_forward = 1
net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.default.accept_source_route = 0
kernel.sysrq = 0
kernel.core_uses_pid = 1
net.ipv4.tcp_syncookies = 1
error: "net.bridge.bridge-nf-call-ip6tables" is an unknown key
error: "net.bridge.bridge-nf-call-iptables" is an unknown key
error: "net.bridge.bridge-nf-call-arptables" is an unknown key
kernel.msgmnb = 65536
kernel.msgmax = 65536
kernel.shmmax = 68719476736
kernel.shmall = 4294967296
配置keepalived:
配置文件在这个位置： /etc/keepalived/keepalived.conf
[root@localhost keepalived-1.2.7]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
test@sina.com
}
notification_email_from admin@test.com
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_instance VI_1 {
state MASTER
interface eth1
virtual_router_id 60
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.146.101
}
}
virtual_server 192.168.146.101 8080 {
delay_loop 6
lb_algo rr
lb_kind DR
nat_mask 255.255.255.0
persistence_timeout 50
protocol TCP
real_server 192.168.146.162 8080 {
weight 1
TCP_CHECK {
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
real_server 192.168.146.163 8080 {
weight 1
TCP_CHECK {
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
}
至此，keepalived配置完成。
把keepalived加入开机自启动，并开启keepalived服务：
[root@localhost keepalived-1.2.7]# chkconfig keepalived on
[root@localhost keepalived-1.2.7]# service keepalived start
Starting keepalived: [ OK ]
查看keepalived进程：
[root@localhost keepalived-1.2.7]# ps aux | grep keepalived
root 1117 0.0 0.0 42172 1000 ? Ss 14:37 0:00 keepalived -D
root 1119 0.0 0.2 44400 2296 ? S 14:37 0:00 keepalived -D
root 1120 0.0 0.1 44276 1664 ? S 14:37 0:00 keepalived -D
root 1165 0.0 0.0 103268 884 pts/5 S+ 14:48 0:00 grep keepalived
查看虚拟IP是否加上：
[root@localhost keepalived-1.2.7]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:b2:88:f7 brd ff:ff:ff:ff:ff:ff
inet 192.168.146.164/24 brd 192.168.146.255 scope global eth1
inet 192.168.146.101/32 scope global eth1
inet6 fe80::20c:29ff:feb2:88f7/64 scope link
valid_lft forever preferred_lft forever
红色部分显示已经自动加上虚拟IP了。
至此，LVS_MASTER服务器已经配置好并启动了。
接下来开始配置部署LVS从服务器：
192.168.146.160 LVS_SALVE：
具体过程同192.168.146.164 LVS_MASTER！！
接下里配置部署两台web服务器：
配置部署192.168.146.162 web1:
配置虚拟IP启动脚本:
[root@localhost ~]# cat /etc/init.d/realserver.sh
SNS_VIP=192.168.146.101
. /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
配置部署tomcat：
[root@localhost ~]# yum -y install tomcat6 tomcat6-webapps tomcat6-admin-webapps
[root@localhost ~]# chkconfig tomcat6 on
[root@localhost ~]# service tomcat6 start
Starting tomcat6: [ OK ]
为了测试方便暂时关闭防火墙：
[root@localhost ~]# service iptables stop
打开浏览器测试：http://192.168.146.142:8080
会看到TOMCAT的熟悉页面了。
为了测试负载均衡，我们将这个页面改下，以更好的标识这个网页是本服务器的
Tomcat6安装目录位于/usr/share/tomcat6，所以我们要编辑tomcat下的webapps/ROOT/index.html这个文件。
[root@localhost ~]# cd /usr/share/tomcat6/webapps/ROOT/
[root@localhost ROOT]# cat /dev/null > index.html
[root@localhost ROOT]# cat index.html
web1 192.168.146.162
启动虚拟IP的脚本：
[root@localhost ROOT]# sh /etc/init.d/realserver.sh start
RealServer Start OK
eth1 Link encap:Ethernet HWaddr 00:0C:29:1F:0F:F3
inet addr:192.168.146.162 Bcast:192.168.146.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fe1f:ff3/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:89543 errors:0 dropped:0 overruns:0 frame:0
TX packets:47914 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:112074876 (106.8 MiB) TX bytes:2870905 (2.7 MiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:22 errors:0 dropped:0 overruns:0 frame:0
TX packets:22 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1408 (1.3 KiB) TX bytes:1408 (1.3 KiB)
lo:0 Link encap:Local Loopback
inet addr:192.168.146.101 Mask:255.255.255.255
UP LOOPBACK RUNNING MTU:16436 Metric:1
运行后会看到网络有了一个虚拟IP，即红色标注部分。
去LVS_MASTER服务器的终端查看下ipvsadm，查看已经连接上了WEB1服务器（即红色标注部分）：
[root@localhost keepalived-1.2.7]# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 192.168.146.101:8080 rr persistent 50
-> 192.168.146.162:8080 Route 1 0 0
已经可以看到有服务器加入进来了。
此时我们访问网页http://192.168.146.101:8080，出现界面显示web1 192.168.146.162；或者使用命令行测试转发情况都可以查看。
配置部署192.168.146.163 web2:
具体配置部署过程同web1！！