聊城手机网站建设价格,北京商标代理,手机建设银行网站进不去,北京万户网络技术有限公司2019独角兽企业重金招聘Python工程师标准 通常说的双机热备是指两台机器都在运行#xff0c;但并不是两台机器都同时在提供服务。当提供服务的一台出现故障的时候#xff0c;另外一台会马上自动接管并且提供服务#xff0c;而且切换的时间非常短。下面来以kee… 2019独角兽企业重金招聘Python工程师标准 通常说的双机热备是指两台机器都在运行但并不是两台机器都同时在提供服务。当提供服务的一台出现故障的时候另外一台会马上自动接管并且提供服务而且切换的时间非常短。下面来以keepalived结合tomcat来实现一个web服务器的双机热备。keepalived的工作原理是VRRPVirtual Router Redundancy Protocol虚拟路由冗余协议。在VRRP中有两组重要的概念VRRP路由器和虚拟路由器主控路由器和备份路由器。VRRP路由器是指运行VRRP的路由器是物理实体虚拟路由器是指VRRP协议创建的是逻辑概念。一组VRRP路由器协同工作共同构成一台虚拟路由器。 Vrrp中存在着一种选举机制用以选出提供服务的路由即主控路由其他的则成了备份路由。当主控路由失效后备份路由中会重新选举出一个主控路由来继续工作来保障不间断服务。我们在本文中的测试环境如下两台物理服务器和一个虚拟服务器(vip):masterredhat 2.6.18-53.el5 192.168.8.4backup: redhat 2.6.18-53.el5 192.168.8.6vip 192.168.8.100测试环境的网络topology图如下:节点A 192.168.8.4 (主节点), 节点B 192.168.8.6(备用节点)虚拟IP(对外提供服务的IP 192.168.8.100)在这种模式下虚拟IP在某时刻只能属于某一个节点另一个节点作为备用节点存在。当主节点不可用时备用节点接管虚拟IP即虚拟IP漂移至节点B提供正常服务。keepalived的原理可以这样简单理解:keepalived安装在两台物理服务器上并相互监控对方是否在正常运行。当节点A正常的时候:节点A上的keepalived会将下面的信息广播出去:192.168.8.100 这个IP对应的MAC地址为节点A网卡的MAC地址图中的其它电脑如客户端和NodeB会更新自己的ARP表对应192.168.8.100的MAC地址节点A网卡的MAC地址。当节点A发生故障的时候节点B上的keepalived会检测到并且将下面的信息广播出去:192.168.8.100 这个IP对应的MAC地址为节点B网卡的MAC地址图中的其它电脑如客户端会更新自己的ARP表对应192.168.8.100的MAC地址节点B网卡的MAC地址。1,在主备机器上安装keepalived步骤如下:下载keepalived-1.1.15.tar.gz然后解压安装#tar zxvf keepalived-1.1.15.tar.gz#cd keepalived-1.1.15#./configure#make#make install2,配置keepalived配置中的state MASTER决定了节点为主节点priority决定了优先级比如在有多个备用节点的时候主节点故障后优先级值大的接管。主节点的配置如下: global_defs {router_id NodeA
}
vrrp_instance VI_1 {state MASTER #设置为主服务器interface eth0 #监测网络接口virtual_router_id 51 #主、备必须一样priority 100 #(主、备机取不同的优先级主机值较大备份机值较小,值越大优先级越高)advert_int 1 #VRRP Multicast广播周期秒数authentication {auth_type PASS #VRRP认证方式主备必须一致auth_pass 1111 #(密码)
}
virtual_ipaddress {192.168.8.100/24 #VRRP HA虚拟地址
} 备用节点的配置如下: global_defs {router_id NodeB
}
vrrp_instance VI_1 {state BACKUP #设置为主服务器interface eth0 #监测网络接口virtual_router_id 51 #主、备必须一样priority 90 #(主、备机取不同的优先级主机值较大备份机值较小,值越大优先级越高)advert_int 1 #VRRP Multicast广播周期秒数authentication {auth_type PASS #VRRP认证方式主备必须一致auth_pass 1111 #(密码)
}
virtual_ipaddress {192.168.8.100/24 #VRRP HA虚拟地址
} 3,启动keepalived:keepalived -D -f /usr/local/etc/keepalived/keepalived.conf查看log消息:tail -f /var/log/messages启动主节点A后的日志为:会广播ARP消息 [rootsrv4 ~]# tail -f /var/log/messages
Sep 20 01:45:29 srv4 Keepalived_vrrp: Configuration is using : 34546 Bytes
Sep 20 01:45:29 srv4 Keepalived_vrrp: VRRP sockpool: [ifindex(2), proto(112), fd(8,9)]
Sep 20 01:45:30 srv4 Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE
Sep 20 01:45:31 srv4 Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE
Sep 20 01:45:31 srv4 Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.
Sep 20 01:45:31 srv4 Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.8.100
Sep 20 01:45:31 srv4 Keepalived_vrrp: Netlink reflector reports IP 192.168.8.100 added
Sep 20 01:45:31 srv4 Keepalived_healthcheckers: Netlink reflector reports IP 192.168.8.100 added
Sep 20 01:45:31 srv4 avahi-daemon[4029]: Registering new address record for 192.168.8.100 on eth0.
Sep 20 01:45:36 srv4 Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.8.100 通过ip a 命令可以看到192.168.8.100/24绑定到了eth0上 [rootsrv4 bin]# ip a
1: lo: LOOPBACK,UP,LOWER_UP mtu 16436 qdisc noqueue link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00inet 127.0.0.1/8 scope host loinet6 ::1/128 scope host valid_lft forever preferred_lft forever
2: eth0: BROADCAST,MULTICAST,UP,LOWER_UP mtu 1500 qdisc pfifo_fast qlen 1000link/ether 00:0c:29:50:2d:9d brd ff:ff:ff:ff:ff:ffinet 192.168.8.4/24 brd 192.168.8.255 scope global eth0inet 192.168.8.100/24 scope global secondary eth0inet6 fe80::20c:29ff:fe50:2d9d/64 scope link valid_lft forever preferred_lft forever 启动备用节点B后的日志为: Sep 20 01:47:31 hadoopsrv Keepalived_vrrp: Configuration is using : 34262 Bytes
Sep 20 01:47:31 hadoopsrv Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE
Sep 20 01:47:31 hadoopsrv Keepalived_vrrp: VRRP sockpool: [ifindex(2), proto(112), fd(7,8)]
Sep 20 01:47:31 hadoopsrv Keepalived: Starting VRRP child process, pid20567 4在两台机器上安装tomcat安装步骤省略安装完成后在节点A的机器上创建一个html文件内容如下 this is the test page
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from server 192.168.8.4 通过下面的url验证能够正常访问http://192.168.8.4:8080/test/test.html安装完成后在节点B的机器上创建一个html文件内容如下 this is the test page
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from server 192.168.8.6 通过下面的url验证能够正常访问http://192.168.8.6:8080/test/test.html在主节点节点A正常的时候通过下面的url访问192.168.8.100:8080/test/test.html返回的内容应该为主节点上的html this is the test page
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from server 192.168.8.4 将节点A的keepalived停止: killall keepalived通过下面的url访问192.168.8.100:8080/test/test.html返回的内容应该为备用节点上的内容 this is the test page
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from server 192.168.8.6 同时查看节点B的日志:发现节点B转为主节点并且会广播ARP消息 Sep 20 01:55:44 hadoopsrv Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE
Sep 20 01:55:45 hadoopsrv Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE
Sep 20 01:55:45 hadoopsrv Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.
Sep 20 01:55:45 hadoopsrv Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.8.100
Sep 20 01:55:45 hadoopsrv avahi-daemon[3769]: Registering new address record for 192.168.8.100 on eth0.
Sep 20 01:55:50 hadoopsrv Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.8.100 本文的目的主要是演示keepalived实现双机热备的功能和过程。对于应用本身(tomcat)发生错误以及脑裂等问题是不能解决的。 转载于:https://my.oschina.net/ydsakyclguozi/blog/515049
