该文章转自: https://www.cloudbility.com/club/7104.html
目录
- 一、当前高可用方案
- 1、Heartbeat+DRBD
- 2、MySQL Cluster
- 3、全局事务ID
- 4、PXC
- 5、MHA的优势
- 1)故障切换快
- 2)master故障不会导致数据不一致
- 3)无需修改当前的MySQL设置
- 4)无需增加大量的服务器
- 5)无性能下降
- 6)适用于任何存储引擎
- 二、MHA简介:
- 1、MHA结构
- 1)MHA Manager
- 1.Manager工具包主要工具
- 2)MHA Node
- 1.Node工具包
- 3)注意
- 1)MHA Manager
- 2、MAH工作原理
- 1、MHA结构
- 三、部署MHA
- 1、环境准备
- 2、安装epel源
- 3、环境初始化
- 1)修改每台主机名
- 2)主机名解析
- 3)ssh无密码登录
- 四、规划mysql
- 1)安装mysql
- 2)配置master、slave01和slave02之间的主从复制
- 3)在master、slave01上创建主从同步的账号。
- 4)在master上执行命令,查看master状态信息
- 5)在slave01和slave02上执行主从同步
- 五、规划mha
- 1)创建mha管理用的复制账号
- 2)在3台主机上(master、slave01和slave02)上分别安装mha4mysql-node包
- 3)在manager上安装mha4mysql-manager和mha4mysql-node包
- 4)修改manager端mha的配置文件
- 5)检查ssh是否畅通
- 6)masterha_check_repl工具检查mysql主从复制是否成功
- 六、mha实验模拟
- 1)在每次做mha实验的时候,我们都最好先执行如下命令做检测
- 2)在manager端启动mha服务并时刻监控日志文件的输出变化
- 3)测试master宕机后会自动切换
- 4)恢复master服务
- 5)再次启动MHA的manager服务,并停止slave01
- 6)恢复slave01服务
- 7)重启MHA的manager服务
- 七、通过vip实现mysql的高可用
- 1)修改/usr/local/mha/mha.cnf
- 2)修改脚本/usr/local/mha/scripts/master_ip_failover
- 3)模拟故障进行切换
- 八、MHA日常维护命令
- 1、查看ssh登陆是否成功
- 2、查看复制是否建立好
- 3、启动mha
- 4、检查启动的状态
- 5、停止mha
- 6、failover后下次重启
- 九、FAQ(常见问题解答)
- 1、可能报错1
- 2、可能报错2
- 3、可能报错3
- 4、可能报错4
- 5、可能报错5
- 6、小知识
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一、当前高可用方案
1、Heartbeat+DRBD
开销:需要额外添加处于被动状态的master server(并不处理应用流量) 性能:为了实现DRBD复制环境的高可用,innodb-flush-log-at-trx-commit和sync-binlog必须设置为1,这样会导致写性能下降。
一致性:在master上必要的binlog时间可能会丢失,这样slave就无法进行复制,导致产生数据一致性问题。
2、MySQL Cluster
MySQL Cluster真正实现了高可用,但是使用的是NDB存储引擎,并且SQL节点有单点故障问题。
半同步复制(5.5+) 半同步复制大大减少了“binlog events只存在故障master上”的问题。
在提交时,保证至少一个slave(并不是所有的)接收到binlog,因此一些slave可能没有接收到binlog。
3、全局事务ID
在二进制文件中添加全局事务ID(global transaction id)需要更改binlog格式,在5.1/5.5版本中不支持。
在应用方面有很多方法可以直线全局事务ID,但是仍避免不了复杂度、性能、数据丢失或者一致性的问题。
4、PXC
PXC实现了服务高可用,数据同步时是并发复制。但是仅支持InnoDB引擎,所有的表都要有主键。锁冲突、死锁问题相对较多等等问题。
5、MHA的优势
1)故障切换快
在主从复制集群中,只要从库在复制上没有延迟,MHA通常可以在数秒内实现故障切换。9-10秒内检查到master故障,可以选择在7-10秒关闭master以避免出现裂脑,几秒钟内,将差异中继日志(relay log)应用到新的master上,因此总的宕机时间通常为10-30秒。恢复新的master后,MHA并行的恢复其余的slave。即使在有数万台slave,也不会影响master的恢复时间。
2)master故障不会导致数据不一致
当目前的master出现故障是,MHA自动识别slave之间中继日志(relay log)的不同,并应用到所有的slave中。这样所有的salve能够保持同步,只要所有的slave处于存活状态。和Semi-Synchronous Replication一起使用,(几乎)可以保证没有数据丢失。
3)无需修改当前的MySQL设置
MHA的设计的重要原则之一就是尽可能地简单易用。MHA工作在传统的MySQL版本5.0和之后版本的主从复制环境中。和其它高可用解决方法比,MHA并不需要改变MySQL的部署环境。MHA适用于异步和半同步的主从复制。
启动/停止/升级/降级/安装/卸载MHA不需要改变(包扩启动/停止)MySQL复制。当需要升级MHA到新的版本,不需要停止MySQL,仅仅替换到新版本的MHA,然后重启MHA Manager就好了。
MHA运行在MySQL 5.0开始的原生版本上。一些其它的MySQL高可用解决方案需要特定的版本(比如MySQL集群、带全局事务ID的MySQL等等),但并不仅仅为了master的高可用才迁移应用的。在大多数情况下,已经部署了比较旧MySQL应用,并且不想仅仅为了实现Master的高可用,花太多的时间迁移到不同的存储引擎或更新的前沿发行版。MHA工作的包括5.0/5.1/5.5的原生版本的MySQL上,所以并不需要迁移。
4)无需增加大量的服务器
MHA由MHA Manager和MHA Node组成。
MHA Node运行在需要故障切换/恢复的MySQL服务器上,因此并不需要额外增加服务器。
MHA Manager运行在特定的服务器上,因此需要增加一台(实现高可用需要2台),但是MHA Manager可以监控大量(甚至上百台)单独的master,因此,并不需要增加大量的服务器。即使在一台slave上运行MHA Manager也是可以的。综上,实现MHA并没用额外增加大量的服务。
5)无性能下降
MHA适用与异步或半同步的MySQL复制。监控master时,MHA仅仅是每隔几秒(默认是3秒)发送一个ping包,并不发送重查询。可以得到像原生MySQL复制一样快的性能。
6)适用于任何存储引擎
MHA可以运行在只要MySQL复制运行的存储引擎上,并不仅限制于InnoDB,即使在不易迁移的传统的MyISAM引擎环境,一样可以使用MHA。
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二、MHA简介:
MHA(Master High Availability),是比较成熟的MySQL高可用方案。MHA能够在30秒内实现故障切换,并能在故障切换中,最大可能的保证数据一致性。目前淘宝也正在开发相似产品TMHA,目前已支持一主一从。
1、MHA结构
该软件由两部分组成:MHA Manager(管理节点)和MHA Node(数据节点)。
1)MHA Manager
可以单独部署在一台独立的机器上管理多个master-slave集群,也可以部署在一台slave节点上。MHA Manager主要运行一些工具,比如masterha_manager工具实现自动监控MySQL Master和实现master故障切换,其它工具实现手动实现master故障切换、在线master转移、连接检查等等。
1.Manager工具包主要工具
masterha_check_ssh 检查MHA的SSH配置状况 masterha_check_repl 检查MySQL复制状况 masterha_manger 启动MHA masterha_check_status 检测当前MHA运行状态 masterha_master_monitor 检测master是否宕机 masterha_master_switch 控制故障转移(自动或者手动) masterha_conf_host 添加或删除配置的server信息
2)MHA Node
MHA Node 运行在每台MySQL服务器上MHA Manager会定时探测集群中的master节点,当master出现故障时,它可以自动将最新数据的slave提升为新的master,然后将所有其他的slave重新指向新的master。整个故障转移过程对应用程序完全透明。
部署在所有运行MySQL的服务器上,无论是master还是slave。主要作用有三个。
Ⅰ、保存二进制日志 如果能够访问故障master,会拷贝master的二进制日志
II、应用差异中继日志 从拥有最新数据的slave上生成差异中继日志,然后应用差异日志。
III、清除中继日志 在不停止SQL线程的情况下删除中继日志
1.Node工具包
这些工具通常由MHA Manager的脚本触发,无需人为操作主要包括以下几个工具:
save_binary_logs 保存和复制master的二进制日志 apply_diff_relay_logs 识别差异的中继日志事件并将其差异的事件应用于其他的slave filter_mysqlbinlog 去除不必要的ROLLBACK事件(MHA已不再使用这个工具) purge_relay_logs 清除中继日志(不会阻塞SQL线程)
3)注意
为了尽可能的减少主库硬件损坏宕机造成的数据丢失,因此在配置MHA的同时建议配置成MySQL 5.5的半同步复制。关于半同步复制原理各位自己进行查阅。(不是必须)
2、MAH工作原理
1.从宕机崩溃的Master保存二进制日志事件(binlog event);
2.识别含有最新更新的Slave;
3.应用差异的中继日志(relay log)到其他Slave;
4.应用从Master保存的二进制日志事件;
5.提升一个Slave为新的Master;
6.使其他的Slave连接新的Master进行复制;
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三、部署MHA
1、环境准备
[root@server01 ~]# cat /etc/redhat-release CentOS release 6.8 (Final) [root@server01 ~]# uname -r 2.6.32-642.el6.x86_64
2、安装epel源
所有节点
#备份 mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup #下载epel源 wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo #生成缓存 yum makecache
3、环境初始化
1)修改每台主机名
172.16.1.241 master 172.16.1.242 slave01 172.16.1.243 slave02 172.16.1.244 manager
其中master对外提供写服务,备选master(实际的slave,主机名slave01)提供读服务,slave也提供相关的读服务,一旦master宕机,将会把备选master提升为新的master,slave指向新的master。
2)主机名解析
#每台服务器执行修改主机名解析
echo ''' 172.16.1.241 master 172.16.1.242 slave01 172.16.1.243 slave02 172.16.1.244 manager''' >>/etc/hosts
3)ssh无密码登录
使用key登录,工作中常用,服务器之间无需密码验证的。关于配置使用key登录,一点需要注意:不能禁止 password 登陆,否则会出现错误
注意:所以全部机器都要相互做密钥登录。服务器间,无密码ssh登录 #主机:master执行命令
[root@master ~]# ssh-keygen -t rsa [root@master ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub root@manager [root@master ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub root@slave01 [root@master ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub root@slave02
#主机:slave01执行命令
[root@slave01 ~]# ssh-keygen -t rsa [root@slave01 ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub root@manager [root@slave01 ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub root@master [root@slave01 ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub root@slave02
#主机: slave02执行命令
[root@slave02 ~]# ssh-keygen -t rsa [root@slave02 ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub root@manager [root@slave02 ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub root@master [root@slave02 ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub root@slave01
#主机:manager执行命令
[root@manager ~]# ssh-keygen -t rsa [root@manager ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub root@master [root@manager ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub root@slave01 [root@manager ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub root@slave02
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四、规划mysql
1)安装mysql
#master配置文件/etc/my.cnf 核心配置如下:
basedir = /application/mysql datadir = /application/mysql/data port = 3306 server_id = 241 socket = /tmp/mysql.sock log-bin=mysql-bin log-slave-updates expire_logs_days = 10
#slave01配置文件/etc/my.cnf 核心配置如下:
basedir = /application/mysql datadir = /application/mysql/data port = 3306 server_id = 242 socket = /tmp/mysql.sock log-bin=mysql-bin log-slave-updates expire_logs_days = 10
#slave02配置文件/etc/my.cnf 核心配置如下:
basedir = /application/mysql datadir = /application/mysql/data port = 3306 server_id = 243 socket = /tmp/mysql.sock log-bin=mysql-bin log-slave-updates expire_logs_days = 10 read_only = 1
2)配置master、slave01和slave02之间的主从复制
注意:binlog-do-db 和 replicate-ignore-db 设置必须相同。 MHA 在启动时候会检测过滤规则,如果过滤规则不同,MHA 不启动监控和故障转移。
在MySQL5.6 的Replication配置中,master端同样要开启两个重要的选项,server-id和log-bin,并且选项server-id在全局架构中并且唯一,不能被其它主机使用,这里采用主机ip地址的最后一位充当server-id的值;slave端要开启relay-log;
#主机: master执行命令
[root@master ~]# egrep "log-bin|server_id" /etc/my.cnf server_id = 241 log-bin=mysql-bin
#主机: slave01执行命令
[root@slave01 ~]# egrep "log-bin|server_id" /etc/my.cnf server_id = 242 log-bin=mysql-bin
#主机: slave02执行命令
[root@slave02 ~]# egrep "log-bin|server_id" /etc/my.cnf server_id = 243 log-bin=mysql-bin
3)在master、slave01上创建主从同步的账号。
slave01是备用master,这个也需要建立授权用户。
#master [root@master ~]# mysql -e "grant replication slave on *.* to 'backup'@'172.16.1.%' identified by 'backup';flush privileges; #slave01 [root@slave01 ~]# mysql -e "grant replication slave on *.* to 'backup'@'172.16.1.%' identified by 'backup';flush privileges;"
4)在master上执行命令,查看master状态信息
[root@master ~]# mysql -e 'show master status;' +------------------+----------+--------------+------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | +------------------+----------+--------------+------------------+ | mysql-bin.000007 | 107 | | | +------------------+----------+--------------+------------------+
5)在slave01和slave02上执行主从同步
#slave01配置主从
[root@slave01 ~]# mysql mysql> change master to master_host='172.16.1.241',master_user='backup',master_password='backup',master_port=3306,master_log_file='mysql-bin.000007',master_log_pos=107; Query OK, 0 rows affected (0.12 sec) mysql> start slave; Query OK, 0 rows affected (0.00 sec) mysql> show slave status\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 172.16.1.241 Master_User: backup Master_Port: 3306 Connect_Retry: 60 Master_Log_File: mysql-bin.000007 Read_Master_Log_Pos: 107 Relay_Log_File: slave01-relay-bin.000002 Relay_Log_Pos: 253 Relay_Master_Log_File: mysql-bin.000007 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 107 Relay_Log_Space: 411 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: 0 Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 0 Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 241 1 row in set (0.00 sec)
#slave02配置主从
[root@slave02 ~]# mysql mysql> change master to master_host='172.16.1.241',master_user='backup',master_password='backup',master_port=3306,master_log_file='mysql-bin.000007',master_log_pos=107; Query OK, 0 rows affected (0.12 sec) mysql> start slave; Query OK, 0 rows affected (0.00 sec) mysql> show slave status\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 172.16.1.241 Master_User: backup Master_Port: 3306 Connect_Retry: 60 Master_Log_File: mysql-bin.000007 Read_Master_Log_Pos: 107 Relay_Log_File: slave01-relay-bin.000002 Relay_Log_Pos: 253 Relay_Master_Log_File: mysql-bin.000007 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 107 Relay_Log_Space: 411 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: 0 Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 0 Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 241 1 row in set (0.00 sec)
#至此主从已经配置完成!
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五、规划mha
1)创建mha管理用的复制账号
每台数据库(master、slave01、slave02)上都要创建账号,在这里以其中master为例.。
[root@master ~]# mysql -e "grant all privileges on *.* to 'mha_rep'@'172.16.1.%' identified by '123456';flush privileges;" [root@master ~]# mysql mysql> select host,user from mysql.user;
2)在3台主机上(master、slave01和slave02)上分别安装mha4mysql-node包
安装完成后会在/usr/local/bin目录下生成以下脚本文件:
-r-xr-xr-x 1 root root 15498 4月 2 16:04 apply_diff_relay_logs # 识别差异的中继日志事件并将其差异的事件应用于其他的slave -r-xr-xr-x 1 root root 4807 4月 2 16:04 filter_mysqlbinlog # 去除不必要的ROLLBACK事件(MHA已不再使用这个工具) -r-xr-xr-x 1 root root 7401 4月 2 16:04 purge_relay_logs # 清除中继日志(不会阻塞SQL线程) -r-xr-xr-x 1 root root 7263 4月 2 16:04 save_binary_logs # 保存和复制master的二进制日志
这里以master为例,其它主机同理。
[root@master ~]# yum install perl-DBD-MySQL -y [root@master ~]# rpm -ivh https://downloads.mariadb.com/files/MHA/mha4mysql-node-0.54-0.el6.noarch.rpm
3)在manager上安装mha4mysql-manager和mha4mysql-node包
MHA Manager中主要包括了几个管理员的命令行工具,例如master_manger,master_master_switch等。MHA Manger也依赖于perl模块,具体如下:
安装完成后会在/usr/local/bin目录下面生成以下脚本文件
-r-xr-xr-x 1 root root 15498 4月 2 15:59 apply_diff_relay_logs # 识别差异的中继日志事件并将其差异的事件应用于其他的slave -r-xr-xr-x 1 root root 4807 4月 2 15:59 filter_mysqlbinlog # 去除不必要的ROLLBACK事件(MHA已不再使用这个工具) -r-xr-xr-x 1 root root 1995 4月 2 16:21 masterha_check_repl # 检查MySQL复制状况 -r-xr-xr-x 1 root root 1779 4月 2 16:21 masterha_check_ssh # 检查MHA的SSH配置状况 -r-xr-xr-x 1 root root 1865 4月 2 16:21 masterha_check_status # 检测当前MHA运行状态 -r-xr-xr-x 1 root root 3201 4月 2 16:21 masterha_conf_host # 添加或删除配置的server信息 -r-xr-xr-x 1 root root 2517 4月 2 16:21 masterha_manager # 启动MHA -r-xr-xr-x 1 root root 2165 4月 2 16:21 masterha_master_monitor # 检测master是否宕机 -r-xr-xr-x 1 root root 2373 4月 2 16:21 masterha_master_switch # 控制故障转移(自动或者手动) -r-xr-xr-x 1 root root 3749 4月 2 16:21 masterha_secondary_check # -r-xr-xr-x 1 root root 1739 4月 2 16:21 masterha_stop # -r-xr-xr-x 1 root root 7401 4月 2 15:59 purge_relay_logs # 清除中继日志(不会阻塞SQL线程) -r-xr-xr-x 1 root root 7263 4月 2 15:59 save_binary_logs # 保存和复制master的二进制日志
复制相关脚本到/usr/local/bin目录(软件包解压缩后就有了,不是必须,因为这些脚本不完整,需要自己修改,这是软件开发着留给我们自己发挥的,如果开启下面的任何一个脚本对应的参数,而对应这里的脚本又没有修改,则会报错,自己被坑的很惨)
[root@manager ~]# cd mha4mysql-manager-0.56/samples/scripts/ # 这是我们下载解压软件的目录 [root@manager scripts]# ll 总用量 32 -rwxr-xr-x 1 root root 3443 1月 8 2012 master_ip_failover #自动切换时vip管理的脚本,不是必须,如果我们使用keepalived的,我们可以自己编写脚本完成对vip的管理,比如监控mysql,如果mysql异常,我们停止keepalived就行,这样vip就会自动漂移 -rwxr-xr-x 1 root root 9186 1月 8 2012 master_ip_online_change #在线切换时vip的管理,不是必须,同样可以可以自行编写简单的shell完成 -rwxr-xr-x 1 root root 11867 1月 8 2012 power_manager #故障发生后关闭主机的脚本,不是必须 -rwxr-xr-x 1 root root 1360 1月 8 2012 send_report #因故障切换后发送报警的脚本,不是必须,可自行编写简单的shell完成。 [root@manager ~]# cp * /usr/local/bin/
#在manager上安装mha4mysql-manager和mha4mysql-node包
[root@manager ~]# yum install perl cpan perl-DBD-MySQL perl-DBD-MySQL perl-Config-Tiny perl-Log-Dispatch perl-Parallel-ForkManager perl-Net-Telnet -y [root@manager ~]# rpm -ivh https://downloads.mariadb.com/files/MHA/mha4mysql-node-0.54-0.el6.noarch.rpm [root@manager ~]# wget https://downloads.mariadb.com/files/MHA/mha4mysql-manager-0.56.tar.gz [root@manager ~]# tar zvxf mha4mysql-manager-0.56.tar.gz [root@manager ~]# cd mha4mysql-manager-0.56 [root@manager ~]# perl Makefile.PL [root@manager mha4mysql-manager-0.56]# make && make install [root@manager mha4mysql-manager-0.56]# mkdir -p /usr/local/mha/scripts [root@manager mha4mysql-manager-0.56]# cp samples/conf/app1.cnf /usr/local/mha/mha.cnf [root@manager mha4mysql-manager-0.56]# cp samples/scripts/* /usr/local/mha/scripts/
4)修改manager端mha的配置文件
记得去注释
[root@manager mha4mysql-manager-0.56]# vim /usr/local/mha/mha.cnf [server default] user=mha_rep #MHA管理mysql的用户名 password=123456 #MHA管理mysql的密码 manager_workdir=/usr/local/mha #MHA的工作目录 manager_log=/usr/local/mha/manager.log #MHA的日志路径 ssh_user=root #免秘钥登陆的用户名 repl_user=backup #主从复制账号,用来在主从之间同步数据 repl_password=backup ping_interval=1 #ping间隔时间,用来检查master是否正常 [server1] hostname=172.16.1.241 master_binlog_dir=/application/mysql/data/ candidate_master=1 #master宕机后,优先启用这台作为master [server2] hostname=172.16.1.242 master_binlog_dir=/application/mysql/data/ candidate_master=1 [server3] hostname=172.16.1.243 master_binlog_dir=/application/mysql/data/ no_master=1
5)检查ssh是否畅通
注意:所有主机之间必须做SSH免密钥登录。否则报错。研究了两天。(通过查看MHA的功能实现过程发现)
[root@manager ~]# masterha_check_ssh --conf=/usr/local/mha/mha.cnf Mon Apr 3 21:42:33 2017 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping. Mon Apr 3 21:42:33 2017 - [info] Reading application default configurations from /usr/local/mha/mha.cnf.. Mon Apr 3 21:42:33 2017 - [info] Reading server configurations from /usr/local/mha/mha.cnf.. Mon Apr 3 21:42:33 2017 - [info] Starting SSH connection tests.. Mon Apr 3 21:42:33 2017 - [debug] Mon Apr 3 21:42:33 2017 - [debug] Connecting via SSH from [email protected](172.16.1.241:22) to [email protected](172.16.1.242:22).. Mon Apr 3 21:42:33 2017 - [debug] ok. Mon Apr 3 21:42:33 2017 - [debug] Connecting via SSH from [email protected](172.16.1.241:22) to [email protected](172.16.1.243:22).. Mon Apr 3 21:42:33 2017 - [debug] ok. Mon Apr 3 21:42:34 2017 - [debug] Mon Apr 3 21:42:34 2017 - [debug] Connecting via SSH from [email protected](172.16.1.243:22) to [email protected](172.16.1.241:22).. Mon Apr 3 21:42:34 2017 - [debug] ok. Mon Apr 3 21:42:34 2017 - [debug] Connecting via SSH from [email protected](172.16.1.243:22) to [email protected](172.16.1.242:22).. Mon Apr 3 21:42:34 2017 - [debug] ok. Mon Apr 3 21:42:34 2017 - [debug] Mon Apr 3 21:42:33 2017 - [debug] Connecting via SSH from [email protected](172.16.1.242:22) to [email protected](172.16.1.241:22).. Mon Apr 3 21:42:33 2017 - [debug] ok. Mon Apr 3 21:42:33 2017 - [debug] Connecting via SSH from [email protected](172.16.1.242:22) to [email protected](172.16.1.243:22).. Mon Apr 3 21:42:34 2017 - [debug] ok. Mon Apr 3 21:42:34 2017 - [info] All SSH connection tests passed successfully.
#如果得到以上结果,表明主机之间ssh互信是畅通的
6)masterha_check_repl工具检查mysql主从复制是否成功
注意:slave01 slave02和master确保已经做好主从复制。否则出错。(研究22个小时)不懂perl 挺麻烦的。
[root@manager ~]# masterha_check_repl --conf=/usr/local/mha/mha.cnf Mon Apr 3 21:44:13 2017 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping. Mon Apr 3 21:44:13 2017 - [info] Reading application default configurations from /usr/local/mha/mha.cnf.. Mon Apr 3 21:44:13 2017 - [info] Reading server configurations from /usr/local/mha/mha.cnf.. Mon Apr 3 21:44:13 2017 - [info] MHA::MasterMonitor version 0.56. Mon Apr 3 21:44:14 2017 - [info] Dead Servers: Mon Apr 3 21:44:14 2017 - [info] Alive Servers: Mon Apr 3 21:44:14 2017 - [info] 172.16.1.241(172.16.1.241:3306) Mon Apr 3 21:44:14 2017 - [info] 172.16.1.242(172.16.1.242:3306) Mon Apr 3 21:44:14 2017 - [info] 172.16.1.243(172.16.1.243:3306) Mon Apr 3 21:44:14 2017 - [info] Alive Slaves: Mon Apr 3 21:44:14 2017 - [info] 172.16.1.242(172.16.1.242:3306) Version=5.5.32-log (oldest major version between slaves) log-bin:enabled Mon Apr 3 21:44:14 2017 - [info] Replicating from 172.16.1.241(172.16.1.241:3306) Mon Apr 3 21:44:14 2017 - [info] Primary candidate for the new Master (candidate_master is set) Mon Apr 3 21:44:14 2017 - [info] 172.16.1.243(172.16.1.243:3306) Version=5.5.32-log (oldest major version between slaves) log-bin:enabled Mon Apr 3 21:44:14 2017 - [info] Replicating from 172.16.1.241(172.16.1.241:3306) Mon Apr 3 21:44:14 2017 - [info] Not candidate for the new Master (no_master is set) Mon Apr 3 21:44:14 2017 - [info] Current Alive Master: 172.16.1.241(172.16.1.241:3306) Mon Apr 3 21:44:14 2017 - [info] Checking slave configurations.. Mon Apr 3 21:44:14 2017 - [info] read_only=1 is not set on slave 172.16.1.242(172.16.1.242:3306). Mon Apr 3 21:44:14 2017 - [warning] relay_log_purge=0 is not set on slave 172.16.1.242(172.16.1.242:3306). Mon Apr 3 21:44:14 2017 - [warning] relay_log_purge=0 is not set on slave 172.16.1.243(172.16.1.243:3306). Mon Apr 3 21:44:14 2017 - [info] Checking replication filtering settings.. Mon Apr 3 21:44:14 2017 - [info] binlog_do_db= , binlog_ignore_db= Mon Apr 3 21:44:14 2017 - [info] Replication filtering check ok. Mon Apr 3 21:44:14 2017 - [info] Starting SSH connection tests.. Mon Apr 3 21:44:16 2017 - [info] All SSH connection tests passed successfully. Mon Apr 3 21:44:16 2017 - [info] Checking MHA Node version.. Mon Apr 3 21:44:16 2017 - [info] Version check ok. Mon Apr 3 21:44:16 2017 - [info] Checking SSH publickey authentication settings on the current master.. Mon Apr 3 21:44:16 2017 - [info] HealthCheck: SSH to 172.16.1.241 is reachable. Mon Apr 3 21:44:17 2017 - [info] Master MHA Node version is 0.54. Mon Apr 3 21:44:17 2017 - [info] Checking recovery script configurations on the current master.. Mon Apr 3 21:44:17 2017 - [info] Executing command: save_binary_logs --command=test --start_pos=4 --binlog_dir=/application/mysql/data/ --output_file=/var/tmp/save_binary_logs_test --manager_version=0.56 --start_file=mysql-bin.000007 Mon Apr 3 21:44:17 2017 - [info] Connecting to [email protected](172.16.1.241).. Creating /var/tmp if not exists.. ok. Checking output directory is accessible or not.. ok. Binlog found at /application/mysql/data/, up to mysql-bin.000007 Mon Apr 3 21:44:17 2017 - [info] Master setting check done. Mon Apr 3 21:44:17 2017 - [info] Checking SSH publickey authentication and checking recovery script configurations on all alive slave servers.. Mon Apr 3 21:44:17 2017 - [info] Executing command : apply_diff_relay_logs --command=test --slave_user='mha_rep' --slave_host=172.16.1.242 --slave_ip=172.16.1.242 --slave_port=3306 --workdir=/var/tmp --target_version=5.5.32-log --manager_version=0.56 --relay_log_info=/application/mysql/data/relay-log.info --relay_dir=/application/mysql/data/ --slave_pass=xxx Mon Apr 3 21:44:17 2017 - [info] Connecting to [email protected](172.16.1.242:22).. Checking slave recovery environment settings.. Opening /application/mysql/data/relay-log.info ... ok. Relay log found at /application/mysql/data, up to slave01-relay-bin.000002 Temporary relay log file is /application/mysql/data/slave01-relay-bin.000002 Testing mysql connection and privileges.. done. Testing mysqlbinlog output.. done. Cleaning up test file(s).. done. Mon Apr 3 21:44:17 2017 - [info] Executing command : apply_diff_relay_logs --command=test --slave_user='mha_rep' --slave_host=172.16.1.243 --slave_ip=172.16.1.243 --slave_port=3306 --workdir=/var/tmp --target_version=5.5.32-log --manager_version=0.56 --relay_log_info=/application/mysql/data/relay-log.info --relay_dir=/application/mysql/data/ --slave_pass=xxx Mon Apr 3 21:44:17 2017 - [info] Connecting to [email protected](172.16.1.243:22).. Checking slave recovery environment settings.. Opening /application/mysql/data/relay-log.info ... ok. Relay log found at /application/mysql/data, up to slave02-relay-bin.000002 Temporary relay log file is /application/mysql/data/slave02-relay-bin.000002 Testing mysql connection and privileges.. done. Testing mysqlbinlog output.. done. Cleaning up test file(s).. done. Mon Apr 3 21:44:18 2017 - [info] Slaves settings check done. Mon Apr 3 21:44:18 2017 - [info] 172.16.1.241 (current master) +--172.16.1.242 +--172.16.1.243 Mon Apr 3 21:44:18 2017 - [info] Checking replication health on 172.16.1.242.. Mon Apr 3 21:44:18 2017 - [info] ok. Mon Apr 3 21:44:18 2017 - [info] Checking replication health on 172.16.1.243.. Mon Apr 3 21:44:18 2017 - [info] ok. Mon Apr 3 21:44:18 2017 - [warning] master_ip_failover_script is not defined. Mon Apr 3 21:44:18 2017 - [warning] shutdown_script is not defined. Mon Apr 3 21:44:18 2017 - [info] Got exit code 0 (Not master dead). MySQL Replication Health is OK.
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六、mha实验模拟
1)在每次做mha实验的时候,我们都最好先执行如下命令做检测
[root@manager ~]# masterha_check_ssh --conf=/usr/local/mha/mha.cnf [root@manager ~]# masterha_check_repl --conf=/usr/local/mha/mha.cnf
#确定两条命令的返回结果都是无异常的,然后启动mha服务
2)在manager端启动mha服务并时刻监控日志文件的输出变化
[root@manager ~]# nohup masterha_manager --conf=/usr/local/mha/mha.cnf > /tmp/mha_manager.log 2>&1 & [root@manager ~]# ps -ef |grep masterha |grep -v 'grep' root 2840 2470 2 10:53 pts/0 00:00:00 perl /usr/local/bin/masterha_manager --conf=/usr/local/mha/mha.cnf
3)测试master宕机后会自动切换
#测试前查看slave01,slave02的主从同步情况
#slave01
[root@slave01 ~]# mysql -e 'show slave status\G' |egrep 'Slave_IO_Running:|Slave_SQL_Running:' Slave_IO_Running: Yes Slave_SQL_Running: Yes
#slave02
[root@slave02 ~]# mysql -e 'show slave status\G' |egrep 'Slave_IO_Running:|Slave_SQL_Running:' Slave_IO_Running: Yes Slave_SQL_Running: Yes
#停止master的mysql服务
[root@master ~]# service mysqld stop Shutting down MySQL (Percona Server)..... SUCCESS!
#manager上查看manager节点日志
[root@manager ~]# cat /usr/local/mha/manager.log ----- Failover Report ----- mha: MySQL Master failover 172.16.1.241 to 172.16.1.242 succeeded Master 172.16.1.241 is down! Check MHA Manager logs at manager:/usr/local/mha/manager.log for details. Started automated(non-interactive) failover. The latest slave 172.16.1.242(172.16.1.242:3306) has all relay logs for recovery. Selected 172.16.1.242 as a new master. 172.16.1.242: OK: Applying all logs succeeded. 172.16.1.243: This host has the latest relay log events. Generating relay diff files from the latest slave succeeded. 172.16.1.243: OK: Applying all logs succeeded. Slave started, replicating from 172.16.1.242. 172.16.1.242: Resetting slave info succeeded. Master failover to 172.16.1.242(172.16.1.242:3306) completed successfully.
从上面的输出可以看出整个MHA的切换过程,共包括以下的步骤:
- 配置文件检查阶段,这个阶段会检查整个集群配置文件配置。
- 宕机的master处理,这个阶段包括虚拟ip摘除操作,主机关机操作(待研究)。
- 复制dead maste和最新slave相差的relay log,并保存到MHA Manger具体的目录下。
- 识别含有最新更新的slave。
- 应用从binlog服务器保存的二进制日志事件(binlog events)。
- 提升一个slave为新的master进行复制。
- 使其他的slave连接新的master进行复制。
6)验证new master(172.16.1.242)
#我们查看slave02的主从同步信息
[root@slave02 ~]# mysql -e 'show slave status\G' |egrep 'Master_Host|Slave_IO_Running:|Slave_SQL_Running:' Master_Host: 172.16.1.242 # 表示已经转移新的ip Slave_IO_Running: Yes # 表示主从OK Slave_SQL_Running: Yes
4)恢复master服务
#manage删除故障转移文件
[root@manager ~]# cat /usr/local/mha/mha.failover.complete [root@manager ~]# rm -rf /usr/local/mha/mha.failover.complete
#master重启mysql服务
[root@master ~]# service mysqld start Starting MySQL... SUCCESS!
#在manager的日志文件中找到主从同步的sql语句
[root@manager ~]# grep MASTER_HOST /usr/local/mha/manager.log Mon Apr 3 21:50:59 2017 - [info] All other slaves should start replication from here. Statement should be: CHANGE MASTER TO MASTER_HOST='172.16.1.242', MASTER_PORT=3306, MASTER_LOG_FILE='mysql-bin.000016', MASTER_LOG_POS=107, MASTER_USER='backup', MASTER_PASSWORD='xxx';
#在master上启动主从同步,密码为backup
master_log_file和master_log_pos参数需要和上面manager的日志文件中同步的语句参数里的值相同。
mysql> change master to master_host='172.16.1.242',master_user='backup',master_password='backup',master_port=3306,master_log_file='mysql-bin.000016',master_log_pos=107; Query OK, 0 rows affected (1.02 sec) mysql> start slave; Query OK, 0 rows affected (0.00 sec)
#在master和slave02上执行,检查主从同步是否都正常,这里以master为例,slave02同理
[root@master ~]# mysql -e 'show slave status\G' |egrep 'Master_Host|Slave_IO_Running:|Slave_SQL_Running:' Master_Host: 172.16.1.242 Slave_IO_Running: Yes Slave_SQL_Running: Yes
5)再次启动MHA的manager服务,并停止slave01
[root@manager ~]# nohup masterha_manager --conf=/usr/local/mha/mha.cnf > /tmp/mha_manager.log 2>&1 &
#关闭slave01的mysql服务
[root@slave01 ~]# service mysqld stop Shutting down MySQL... SUCCESS [root@slave01 ~]#tail -f /usr/local/mha/manager.log ----- Failover Report ----- mha: MySQL Master failover 172.16.1.242 to 172.16.1.241 succeeded Master 172.16.1.242 is down! Check MHA Manager logs at manager:/usr/local/mha/manager.log for details. Started automated(non-interactive) failover. The latest slave 172.16.1.241(172.16.1.241:3306) has all relay logs for recovery. Selected 172.16.1.241 as a new master. 172.16.1.241: OK: Applying all logs succeeded. 172.16.1.243: This host has the latest relay log events. Generating relay diff files from the latest slave succeeded. 172.16.1.243: OK: Applying all logs succeeded. Slave started, replicating from 172.16.1.241. 172.16.1.241: Resetting slave info succeeded. Master failover to 172.16.1.241(172.16.1.241:3306) completed successfully.
出现故障的快速恢复步骤
[root@slave01 ~]# service mysqld stop Shutting down MySQL... SUCCESS [root@manager mha]# tail -f /usr/local/mha/manager.log ----- Failover Report ----- mha: MySQL Master failover 172.16.1.242 Master 172.16.1.242 is down! Check MHA Manager logs at manager:/usr/local/mha/manager.log for details. Started automated(non-interactive) failover. The latest slave 172.16.1.241(172.16.1.241:3306) has all relay logs for recovery. Got Error so couldn't continue failover from here. #出现无法切换回去,后来经过排查是manager /usr/local/mha/mha.cnf [server1] (比较低级的错误,排查很久。不过主要是想跟大家分享出现问题如何恢复到之前的状态。) hostname=172.16.1.241 master_binlog_dir=/application/mysql/data/ candidate_master=1r #这里多加了一个r。 #修改完毕 hostname=172.16.1.241 master_binlog_dir=/application/mysql/data/ candidate_master=1 实现文件手动恢复到之前的状态。 #manager [root@manager ~]# rm -rf /usr/local/mha/mha.failover.complete [root@manager ~]# rm -rf /usr/local/mha/mha.failover.error [root@manager ~]# nohup masterha_manager --conf=/usr/local/mha/mha.cnf > /tmp/mha_manager.log 2>&1 & #master [root@master ~]# mysql mysql> stop slave; mysql> reset slave; mysql> show master status\G *************************** 1. row *************************** File: mysql-bin.000013 Position: 107 Binlog_Do_DB: Binlog_Ignore_DB: 1 row in set (0.00 sec) #slave01 [root@slave01 ~]# mysql mysql> stop slave; mysql> change master to master_host='172.16.1.241',master_user='backup',master_password='backup',master_port=3306,master_log_file='mysql-bin.000013',master_log_pos=107; mysql> start slave; # slave01和slave02恢复之前的状态。 [root@slave01 ~]# mysql -e 'show slave status\G' |egrep 'Master_Host|Slave_IO_Running:|Slave_SQL_Running:' Master_Host: 172.16.1.241 Slave_IO_Running: Yes Slave_SQL_Running: Yes [root@slave02 ~]# mysql -e 'show slave status\G' |egrep 'Master_Host|Slave_IO_Running:|Slave_SQL_Running:' Master_Host: 172.16.1.241 Slave_IO_Running: Yes Slave_SQL_Running: Yes
#manager上查看manager节点日志
[root@manager ~]# cat /usr/local/mha/manager.log ----- Failover Report ----- mha: MySQL Master failover 172.16.1.242 Master 172.16.1.242 is down! Check MHA Manager logs at manager:/usr/local/mha/manager.log for details. Started automated(non-interactive) failover. The latest slave 172.16.1.241(172.16.1.241:3306) has all relay logs for recovery. Got Error so couldn't continue failover from here.
6)恢复slave01服务
#删除故障转移文件
[root@manager ~]# rm -rf /usr/local/mha/mha.failover.complete
#重启mysql服务
[root@slave01 ~]# service mysqld start Starting MySQL.. SUCCESS!
#在manager的日子文件中找到主从同步的sql语句
[root@manager ~]# grep MASTER_HOST /usr/local/mha/manager.log Tue Apr 4 02:47:33 2017 - [info] All other slaves should start replication from here. Statement should be: CHANGE MASTER TO MASTER_HOST='172.16.1.241', MASTER_PORT=3306, MASTER_LOG_FILE='mysql-bin.000015', MASTER_LOG_POS=107, MASTER_USER='backup', MASTER_PASSWORD='xxx';
#在slave01上启动主从同步,密码为backup 记得修改MASTER_PASSWORD='xxx' 为 MASTER_PASSWORD='bakcup'
[root@slave01 ~]# mysql mysql> stop slave mysql> CHANGE MASTER TO MASTER_HOST='172.16.1.241', MASTER_PORT=3306, MASTER_LOG_FILE='mysql-bin.000015', MASTER_LOG_POS=107, MASTER_USER='backup', MASTER_PASSWORD='backup'; Query OK, 0 rows affected (0.39 sec) mysql> start slave; Query OK, 0 rows affected (0.00 sec)
#在slave01和slave02上执行,检查主从同步是否都正常,
#slave01 [root@slave01 ~]# mysql -e 'show slave status\G' |egrep 'Master_Host|Slave_IO_Running:|Slave_SQL_Running:' Master_Host: 172.16.1.241 Slave_IO_Running: Yes Slave_SQL_Running: Yes #slave02 [root@slave02 ~]# mysql -e 'show slave status\G' |egrep 'Master_Host|Slave_IO_Running:|Slave_SQL_Running:' Master_Host: 172.16.1.241 Slave_IO_Running: Yes Slave_SQL_Running: Yes
7)重启MHA的manager服务
[root@manager ~]# nohup masterha_manager --conf=/usr/local/mha/mha.cnf > /tmp/mha_manager.log 2>&1 & [1] 30389
七、通过vip实现mysql的高可用
1)修改/usr/local/mha/mha.cnf
[server default] user=mha_rep password=123456 manager_workdir=/usr/local/mha manager_log=/usr/local/mha/manager.log ssh_user=root master_ip_failover_script=/usr/local/mha/scripts/master_ip_failover #添加管理vip的脚本 repl_user=backup repl_password=backup ping_interval=1 [server1] hostname=172.16.1.241 master_binlog_dir=/application/mysql/data/ candidate_master=1 port=3306 [server2] hostname=172.16.1.242 master_binlog_dir=/application/mysql/data/ candidate_master=1 port=3306 [server3] hostname=172.16.1.243 master_binlog_dir=/application/mysql/data/ port=3306 no_master=1
2)修改脚本/usr/local/mha/scripts/master_ip_failover
#!/usr/bin/env perl use strict; use warnings FATAL => 'all'; use Getopt::Long; my ( $command, $ssh_user, $orig_master_host, $orig_master_ip, $orig_master_port, $new_master_host, $new_master_ip, $new_master_port ); my $vip = '172.16.1.240'; #vip地址 my $key = '1'; my $ssh_start_vip = "/sbin/ifconfig eth1:$key $vip"; #绑定在指定的网卡上面 my $ssh_stop_vip = "/sbin/ifconfig eth1:$key down"; #我的机器有两块网卡eth1是172网段的所有我把vip绑定在eth1上,我的eth0网段是10.0.0.%。 GetOptions( 'command=s' => \$command, 'ssh_user=s' => \$ssh_user, 'orig_master_host=s' => \$orig_master_host, 'orig_master_ip=s' => \$orig_master_ip, 'orig_master_port=i' => \$orig_master_port, 'new_master_host=s' => \$new_master_host, 'new_master_ip=s' => \$new_master_ip, 'new_master_port=i' => \$new_master_port, ); exit &main(); sub main { print "\n\nIN SCRIPT TEST====$ssh_stop_vip==$ssh_start_vip===\n\n"; if ( $command eq "stop" || $command eq "stopssh" ) { my $exit_code = 1; eval { print "Disabling the VIP on old master: $orig_master_host \n"; &stop_vip(); $exit_code = 0; }; if ($@) { warn "Got Error: $@\n"; exit $exit_code; } exit $exit_code; } elsif ( $command eq "start" ) { my $exit_code = 10; eval { print "Enabling the VIP - $vip on the new master - $new_master_host \n"; &start_vip(); $exit_code = 0; }; if ($@) { warn $@; exit $exit_code; } exit $exit_code; } elsif ( $command eq "status" ) { print "Checking the Status of the script.. OK \n"; exit 0; } else { &usage(); exit 1; } } sub start_vip() { `ssh $ssh_user\@$new_master_host \" $ssh_start_vip \"`; } # A simple system call that disable the VIP on the old_master sub stop_vip() { `ssh $ssh_user\@$orig_master_host \" $ssh_stop_vip \"`; } sub usage { print "Usage: master_ip_failover --command=start|stop|stopssh|status --orig_master_host=host --orig_master_ip=ip --orig_master_port=port --new_master_host=host --new_master_ip=ip --new_master_port=port\n"; }
3)模拟故障进行切换
#停止master的mysql服务
[root@master ~]# service mysqld stop Shutting down MySQL... SUCCESS!
#查看slave02的同步信息
[root@slave02 ~]# mysql -e 'show slave status\G' |egrep 'Master_Host|Slave_IO_Running:|Slave_SQL_Running:' Master_Host: 172.16.1.242 Slave_IO_Running: Yes Slave_SQL_Running: Yes
#查看slave01的IP信息
[root@slave01 ~]# ifconfig eth0 Link encap:Ethernet HWaddr 00:1C:42:58:08:EF inet addr:10.0.0.242 Bcast:10.0.0.255 Mask:255.255.255.0 inet6 addr: fe80::21c:42ff:fe58:8ef/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:6925 errors:0 dropped:0 overruns:0 frame:0 TX packets:2869 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:679548 (663.6 KiB) TX bytes:420365 (410.5 KiB) eth0:1 Link encap:Ethernet HWaddr 00:1C:42:58:08:EF inet addr:172.16.1.240 Bcast:172.16.255.255 Mask:255.255.0.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 eth1 Link encap:Ethernet HWaddr 00:1C:42:F4:DF:3E inet addr:172.16.1.242 Bcast:172.16.1.255 Mask:255.255.255.0 inet6 addr: fe80::21c:42ff:fef4:df3e/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:10272 errors:0 dropped:0 overruns:0 frame:0 TX packets:7875 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:1575148 (1.5 MiB) TX bytes:1644494 (1.5 MiB) eth1:1 Link encap:Ethernet HWaddr 00:1C:42:F4:DF:3E inet addr:172.16.1.240 Bcast:172.16.255.255 Mask:255.255.0.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 # 这可以看到我们添加的VIP已经自动添加了 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:65536 Metric:1 RX packets:640 errors:0 dropped:0 overruns:0 frame:0 TX packets:640 errors:0 dropped:0 overruns:0 carrier