centos6.4下LVS+keepalived的高可用（LVS/DR模式）-白红宇

centos6.4下LVS+keepalived的高可用（LVS/DR模式）

阅读量：6068 次

发布时间：2019-06-20

本文共 6455 字，大约阅读时间需要 21 分钟。

LVS负载均衡机制：

LVS工作在网络层。相对于其它负载均衡的解决办法，比如DNS域名轮流解析、应用层负载的调度、客户端的调度等，它的效率是非常高的。LVS的通过控制IP来实现负载均衡。IPVS是其具体的实现模块。IPVS的主要作用：安装在Director Server上面，在Director Server虚拟一个对外访问的IP（VIP）。用户访问VIP，到达Director Server，Director Server根据一定的规则选择一个Real Server，处理完成后然后返回给客户端数据。这些步骤产生了一些具体的问题，比如如何选择具体的Real Server，Real Server如果返回给客户端数据等等。IPVS为此有三种机制：

1.VS/NAT(Virtual Server via Network Address Translation)，即网络地址翻转技术实现虚拟服务器。当请求来到时，Diretor server上处理的程序将数据报文中的目标地址（即虚拟IP地址）改成具体的某台Real Server,端口也改成Real Server的端口，然后把报文发给Real Server。Real Server处理完数据后，需要返回给Diretor Server，然后Diretor server将数据包中的源地址和源端口改成VIP的地址和端口，最后把数据发送出去。由此可以看出，用户的请求和返回都要经过Diretor Server，如果数据过多，Diretor Server肯定会不堪重负。

2.VS/TUN（Virtual Server via IP Tunneling）,即IP隧道技术实现虚拟服务器。它跟VS/NAT基本一样，但是Real server是直接返回数据给客户端，不需要经过Diretor server,这大大降低了Diretor server的压力。

3.VS/DR（Virtual Server via Direct Routing），即用直接路由技术实现虚拟服务器。跟前面两种方式，它的报文转发方法有所不同，VS/DR通过改写请求报文的MAC地址，将请求发送到Real Server，而Real Server将响应直接返回给客户，免去了VS/TUN中的IP隧道开销。这种方式是三种负载调度机制中性能最高最好的，但是必须要求Director Server与Real Server都有一块网卡连在同一物理网段上

//环境介绍

#VS/DR模式下，Direct server在VIP:80端口监听用户请求，改写请求报文的MAC地址，将请求负载到real server上，real server将响应直接返回给用户，因此所有的主机必须在同一个网段，且real server可以直接与用户通信

1.主机配置

DIRECT SERVER:10.10.54.155

vip:10.10.54.151

DIRECT BACKUP:10.10.54.156

vip:10.10.54.151

real server:10.10.54.222(80) --nginx

real server:10.10.54.226(80) --nginx

//软件安装

1.所需软件ipvsadm-1.26.tar.gzkeepalived-1.2.9.tar.gz2.安装ipvsadmshell> yum -y install wget libnl* popt* gcc.x86_64 gcc-c++.x86_64 gcc-objc++.x86_64 kernel-devel.x86_64 make popt-static.x86_64shell> tar xvf ipvsadm-1.26.tar.gzshell> cd ipvsadm-1.26shell> ./configure && make && make install3.安装keepalivedshell> yum install -y net-snmp.x86_64 net-snmp-devel.x86_64shell> tar xvf keepalived-1.2.9.tar.gzshell> cd keepalived-1.2.9shell> ./configure && make && make installshell> ./configure --prefix=/usr/local/keepalived --enable-snmp --sysconfdir=/etcshell> cp /usr/local/keepalived/sbin/keepalived /sbin/shell> cp /usr/local/keepalived/bin/genhash /bin/

//【real server上操作】

1.编辑realserver脚本shell> vim /etc/init.d/realserver-----------------------------------------------------#!/bin/bash#description:start realserver#script_name:realserver_configVIP=10.10.54.151#虚拟IPsource/etc/init.d/functionscase"$1"instart)echo"start LVS of realserver."/sbin/ifconfiglo:0 $VIP broadcast $VIP netmask 255.255.255.255 upecho"1"> /proc/sys/net/ipv4/conf/lo/arp_ignoreecho"2"> /proc/sys/net/ipv4/conf/lo/arp_announceecho"1"> /proc/sys/net/ipv4/conf/all/arp_ignoreecho"2"> /proc/sys/net/ipv4/conf/all/arp_announce;;stop)/sbin/ifconfiglo:0 downecho"0"> /proc/sys/net/ipv4/conf/lo/arp_ignoreecho"0"> /proc/sys/net/ipv4/conf/lo/arp_announceecho"0"> /proc/sys/net/ipv4/conf/all/arp_ignoreecho"0"> /proc/sys/net/ipv4/conf/all/arp_announce;;*)echo"Usage: $0 {start|stop}"exit1esac-----------------------------------------------------------------2.shell> /etc/init.d/realserverstart

//【Direct server上操作】

1.[master]修改配置文件shell> vim /etc/keepalived/keepalived.conf---------------------------------------------global_defs {notification_email {lij@***.com}notification_email_from lij@***.comsmtp_server lij@***.comsmtp_connect_timeout 30router_id LVS_MASTER2}vrrp_instance VI_1 {state MASTERinterface eth0virtual_router_id 51priority 100advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {10.10.54.151/24dev eth0 label eth0:1#虚拟IP，用户可见IP}}virtual_server 10.10.54.151 80 {delay_loop 6lb_algo rrlb_kind DR# nat_mask 255.255.255.0# persistence_timeout 50protocol TCPreal_server 10.10.54.157 80 {#real server上80端口weight 1TCP_CHECK {connect_timeout 3nb_get_retry 3delay_before_retry 3connect_port 80}}real_server 10.10.54.159 80 {weight 1TCP_CHECK {connect_timeout 3nb_get_retry 3delay_before_retry 3connect_port 80}}}#查看IPVS表shell> ipvsadm -lnIP Virtual Server version 1.2.1 (size=4096)Prot LocalAddress:Port Scheduler Flags-> RemoteAddress:Port Forward Weight ActiveConn InActConnTCP 10.10.54.151:80 rr-> 10.10.54.157:80 Route 1 0 0-> 10.10.54.159:80 Route 1 0 0--------------------------------------------------

2.【backup server】修改配置文件

---------------------------------------------------global_defs {notification_email {lij@***.com}notification_email_from lij@***.comsmtp_server lij@***.comsmtp_connect_timeout 30router_id LVS_BACKUP #改1}vrrp_instance VI_1 {state MASTER #改2interface eth0virtual_router_id 51priority 80 #改3advert_int 1authentication {auth_type PASSauth_pass 1111}...}#backup上查看IPVS表shell> ipvsadm -lnIP Virtual Server version 1.2.1 (size=4096)Prot LocalAddress:Port Scheduler Flags-> RemoteAddress:Port Forward Weight ActiveConn InActConnTCP 10.10.54.151:80 rr-> 10.10.54.157:80 Route 1 0 0-> 10.10.54.159:80 Route 1 0 0-----------------------------------------------

//telnet 测试负载均衡和故障转移

测试负载均衡

1.master 和 backup上启动keepalived

/etc/init.d/keepalived start

2.150主机上telnet VIP

shell> telnet 10.10.54.151 80

Trying 10.10.54.151...

Connected to 10.10.54.151.

Escape character is '^]'.

3.master主机上查看IPVS信息

shell> ipvsadm -ln

IP Virtual Server version 1.2.1 (size=4096)