使用masterha_master_switch工具实现MySQL高可用MHA的自动切换

本文主要给大家介绍使用masterha_master_switch工具实现MySQL高可用MHA的自动切换，文章内容都是笔者用心摘选和编辑的，具有一定的针对性，对大家的参考意义还是比较大的，下面跟笔者一起了解下使用masterha_master_switch工具实现MySQL高可用MHA的自动切换吧。

简介：masterha_master_switch作为一个切换工具被集成在MHA程序包中，

安装：编译安装MHA manager后会在/usr/local/bin/中生成二进制可执行程序masterha_master_switch。

使用：

$masterha_master_switch --helpUsage:    # For master failover    masterha_master_switch --master_state=dead    --global_conf=/etc/masterha_default.cnf    --conf=/usr/local/masterha/conf/app1.cnf --dead_master_host=host1    # For online master switch    masterha_master_switch --master_state=alive    --global_conf=/etc/masterha_default.cnf    --conf=/usr/local/masterha/conf/app1.cnf    See online reference    (http://code.google.com/p/mysql-master-ha/wiki/masterha_master_switch)    for details.

在这里，我习惯将一套主从的配置都放在app1.cnf中，并且更改为业务相关的名称，如mainBusiness.cnf

分析：

目标：获取masterha_master_switch的在线切换逻辑环境：MHA manager 192.168.1.8       MHA node1+MySQL5.7+GTID 192.168.1.109+PORT3109     主       MHA node1+MySQL5.7+GTID 192.168.1.110+PORT3110     从

配置文件内容：

manager_workdir=/data/mha/mainBusiness                 #设置MHA的工作目录manager_log=/data/mha/mainBusiness/manager.log         #MHA manager的日志输出remote_workdir=/data/mha/                              #预设MHA node端的工作目录master_binlog_dir= /data/mysql/3109/log/,/data/mysql/3110/log/  #预设MHA node端的binlog目录                                                                                       #secondary_check_script= masterha_secondary_check -s 192.168.1.109 -s 192.168.1.110                                                                    secondary_check_script= masterha_secondary_check -s 192.168.1.109 -s 192.168.1.110 --user=root --master_host=192.168.1.109 --master_port=3109          ping_interval=1                                       #设置MHA manager的检测间隔（1秒）[server1]hostname=MySQL-Cent7-IP001109ip=192.168.1.109port=3109ssh_user=rootssh_port=22candidate_master=1                                    #设置该节点是否可以提升为主，1为是,0否check_repl_delay=0                                    #发生故障后是否检查本实例主从落后程度,0否,1是[server2]hostname=MySQL-Cent7-IP001110ip=192.168.1.110port=3110ssh_user=rootssh_port=22candidate_master=1                                    #设置该节点是否可以提升为主，1为是,0否check_repl_delay=0                                    #发生故障后是否检查本实例主从落后程度,0否,1是    在MHA manager端上执行：$masterha_master_switch --master_state=alive --conf=/etc/mha/mainBusiness.cnf  --orig_master_is_new_slave#--master_state             指明在线切换#--orig_master_is_new_slave 指定原先的主作为从库挂到新的主上

MHA manager端输出如下

#####################输出段1###########################[info] MHA::MasterRotate version 0.57.[info] Starting online master switch..        #开始在线切换[info] [info] * Phase 1: Configuration Check Phase.. #阶段1,检查配置[info] [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping..             #我这里没有使用全局参数文件，会有报错跳过，没关系[info] Reading application default configuration from /etc/mha/mainBusiness.cnf..               #程序从mainBusiness文件中读取配置                                         [info] Reading server configuration from /etc/mha/mainBusiness.cnf..[info] GTID failover mode = 1                #启用GTID故障转移模式[info] Current Alive Master: MySQL-Cent7-IP001109(192.168.1.109:3109)  #列出当前存活的主实例[info] Alive Slaves:                         #列出当前存活的从实例[info]   MySQL-Cent7-IP001110(192.168.1.110:3110)  Version=5.7.19-log (oldest major version between slaves) log-bin:enabled[info]   GTID ON                             #从采用了GTID模式[info]   Replicating from 192.168.1.109(192.168.1.109:3109)[info]   Primary candidate for the new Master (candidate_master is set)It is better to execute FLUSH NO_WRITE_TO_BINLOG TABLES on the master before switching. Is it ok to execute on MySQL-Cent7-IP001109(192.168.1.109:3109)? (YES/no): #处于事务一致性考虑，程序询问是否临时关闭非事务型的表

原master，3109端显示如下

#####################输出段1###########################SET wait_timeout=86400;                                #设置连接超时时间，防止切换时翻车SELECT @@global.server_id As Value;                    SELECT VERSION() AS Value;                             #获取用于复制的server-idSELECT @@global.gtid_mode As Value;                    #获取自身是否使用了GTID复制SHOW GLOBAL VARIABLES LIKE 'log_bin';                  #检查自身是否启用了binlogSHOW MASTER STATUS;                                    #获取自身的事务执行情况SELECT @@global.datadir AS Value;                      #获取自身数据文件的存储位置SELECT @@global.slave_parallel_workers AS Value;       #检查是否采用了多线程复制SHOW SLAVE STATUS;                                     #获取自身作为从库时的事务执行情况SELECT @@global.read_only As Value;                    #获取自身是否开启了只读SELECT @@global.relay_log_purge As Value;              #检查自身是否开启了relay log自动清除

原slave,3110端显示如下

SELECT @@global.server_id As Value;SELECT VERSION() AS Value;SELECT @@global.gtid_mode As Value;SHOW GLOBAL VARIABLES LIKE 'log_bin';SHOW MASTER STATUS;SELECT @@global.datadir AS Value;SELECT @@global.slave_parallel_workers AS Value;SHOW SLAVE STATUS;SELECT @@global.read_only As Value;SELECT @@global.relay_log_purge As Value;SELECT @@global.relay_log_info_repository AS Value;     #差异处，获取自身relay信息保存形式（table）SELECT Relay_log_name FROM mysql.slave_relay_log_info;  #差异处，获取正在使用的relay文件名称SELECT @@global.datadir AS Value;                       SHOW SLAVE STATUS;SELECT Repl_slave_priv AS Value FROM mysql.user WHERE user = 'repl';  #差异处，检查复制用户是否具有复制权限

第一部分小结：

        读取配置文件，确认主从关系与复制方式；        根据主从关系复制方式，连接主库：设置必要参数，获取的复制详细信息/                            连接从库：获取复制的详细信息，获取relay信息，获取repl账号并确认权限

接MHA manager端输出确认输入yes后

MHA manager端输出如下：

#####################输出段2###########################[info] Executing FLUSH NO_WRITE_TO_BINLOG TABLES. This may take long time..[info]  ok.               #注意，这里虽然显示关闭了非事务表，但是上面的抓包语句里面并没有出现相关语句[info] Checking MHA is not monitoring or doing failover..  #检查MHA是否工作，切换时要求MHA manager停止运行[info] Checking replication health on MySQL-Cent7-IP001110.. #检查主从健康程度[info]  ok.[info] Searching new master from slaves..                    #开始在从库中选取一个新主[info]  Candidate masters from the configuration file:       #列出候选从库[info]   MySQL-Cent7-IP001109(192.168.1.109:3109)  Version=5.7.19-log log-bin:enabled[info]     GTID ON                                          #检查GTID开启情况[info]   MySQL-Cent7-IP001110(192.168.1.110:3110)  Version=5.7.19-log (oldest major version between slaves) log-bin:enabled[info]     GTID ON                                          #检查GTID开启情况[info]     Replicating from 192.168.1.109(192.168.1.109:3109)[info]     Primary candidate for the new Master (candidate_master is set)[info]  Non-candidate masters:[info]  Searching from candidate_master slaves which have received the latest relay log events..[info] #在所有从库中选取relay log最新的一个作为新的主库From:MySQL-Cent7-IP001109(192.168.1.109:3109) (current master) +--MySQL-Cent7-IP001110(192.168.1.110:3110)To:MySQL-Cent7-IP001110(192.168.1.110:3110) (new master) +--MySQL-Cent7-IP001109(192.168.1.109:3109)Starting master switch from MySQL-Cent7-IP001109(192.168.1.109:3109) to MySQL-Cent7-IP001110(192.168.1.110:3110)? (yes/NO): #程序询问是否可以进行切换了

master，3109端显示如下

#####################输出段2###########################USE `unknown_database`;FLUSH NO_WRITE_TO_BINLOG TABLES;                              -- 刷新表缓存到硬盘，同时不记录这条到binlogSELECT GET_LOCK('MHA_Master_High_Availability_Monitor', '0') AS Value;   -- 加一个模拟锁，防止出现切换程序多开的问题，这样多开的程序以为获取不到同名锁就会失败退出，#GET_LOCK(str,time) -- str为锁的名称，0表示持续锁,5.7.5之后可以存在多个名称不同的GET_LOCKSHOW PROCESSLIST;

原slave，3110端显示如下

#####################输出段2###########################USE `unknown_database`;SELECT GET_LOCK('MHA_Master_High_Availability_Failover', '0') AS Value;SHOW SLAVE STATUS;SHOW SLAVE STATUS;

第二部分小结：

        1.确认可以保存关闭表后，刷新表缓存到磁盘， 避免丢数据，加模拟锁防止切换程序多开造成切换异常        2.从候选从库中选出拥有最新数据的从库，并将其设为要切换到的主库

接MHA manager端输出确认可以切换后

MHA manager端输出如下：

#####################输出段3###########################[info] Checking whether MySQL-Cent7-IP001110(192.168.1.110:3110) is ok for the new master..[info]  ok.   #检查上一步中被选定的新主库的是否真正可以成为主[info] MySQL-Cent7-IP001109(192.168.1.109:3109): SHOW SLAVE STATUS returned empty result. To check replication filtering rules, temporarily executing CHANGE MASTER to a dummy host.          #没有检查到原来主（现在被作为从）作为从库的残留信息，不管3721先将其挂到一个空主上[info] MySQL-Cent7-IP001109(192.168.1.109:3109): Resetting slave pointing to the dummy host.[info] ** Phase 1: Configuration Check Phase completed.[info] # 配置检查阶段结束[info] * Phase 2: Rejecting updates Phase..[info] #master_ip_online_change_script is not defined. If you do not disable writes on the current master manually, applications keep writing on the current master. Is it ok to proceed? (yes/NO):#切换程序检测到主机虚拟IP地址切换的地址没有定义，如果只切换主从身份的话，应用还会写到原来的主上，需要设置只读。询问是否真的要切换，这里我们只是做切换实验，先观察下两个实例的输出，然后直接切换即可。

原master，3109端显示如下

USE `unknown_database`;FLUSH NO_WRITE_TO_BINLOG TABLES;                                -- 刷新表缓存到磁盘， 避免同步丢数据的问题SELECT GET_LOCK('MHA_Master_High_Availability_Monitor', '0') AS Value;   SHOW PROCESSLIST;SHOW SLAVE STATUS;CHANGE MASTER TO MASTER_HOST='dummy_host';                               #将原主作为从切换到一个莫须有的主机上SHOW SLAVE STATUS;RESET SLAVE /*!50516 ALL */;                                             #尝试清除自己之前残存的slave属性的信息，若本机不为主时，需要！SELECT RELEASE_LOCK('MHA_Master_High_Availability_Monitor') As Value;    

原slave，3110端显示如下

USE `unknown_database`;SELECT GET_LOCK('MHA_Master_High_Availability_Failover', '0') AS Value;SHOW SLAVE STATUS;SHOW SLAVE STATUS;SHOW PROCESSLIST;

第三部分总结：

    1.检查选定的从库的详细信息，确认真的是否可以作为新的主库    2.处理从库之间的数据比对，若只有一个主和从，则将原主库先挂到一个莫须有的空主上                            若有两个以上的从库，则需清理从库原来的slave记录

接MHA manager端输出确认，强制切换后：

MHA manager端输出如下：

#####################输出段4###########################[info] Locking all tables on the orig master to reject updates from everybody (including root):[info] Executing FLUSH TABLES WITH READ LOCK..[info]  ok.   #所有的表都禁止写操作[info] Orig master binlog:pos is 3109binlog.000070:536.[info]  Waiting to execute all relay logs on MySQL-Cent7-IP001110(192.168.1.110:3110)..[info]  master_pos_wait(3109binlog.000070:536) completed on MySQL-Cent7-IP001110(192.168.1.110:3110). Executed 0 events.[info]   done.#将从库已经获得，但还未来得及执行的事务应用到自身，和其他没有跟上的从库[info] Getting new master`s binlog name and position..[info]  3110binlog.000049:536[info]  All other slaves should start replication from here. Statement should be: CHANGE MASTER TO MASTER_HOST='MySQL-Cent7-IP001110 or 192.168.1.110', MASTER_PORT=3110, MASTER_AUTO_POSITION=1, MASTER_USER='repl', MASTER_PASSWORD='xxx';[info] Setting read_only=0 on MySQL-Cent7-IP001110(192.168.1.110:3110)..[info]  ok.   #即将所有其他从库都用change master的语句切换到新的主，即原来的从110上[info] [info] * Switching slaves in parallel..[info]        #即将并行切换所有从库[info] Unlocking all tables on the orig master: [info] Executing UNLOCK TABLES..[info]  ok.   #释放原主库的表锁[info] Starting orig master as a new slave..[info]  Resetting slave MySQL-Cent7-IP001109(192.168.1.109:3109) and starting replication from the new master MySQL-Cent7-IP001110(192.168.1.110:3110)..[info]  Executed CHANGE MASTER.[info]  Slave started.[info] All new slave servers switched successfully.[info]        [info] * Phase 5: New master cleanup phase..[info]        #即将清理新从库的主从信息，切换到主库[info]  MySQL-Cent7-IP001110: Resetting slave info succeeded.[info] Switching master to MySQL-Cent7-IP001110(192.168.1.110:3110) completed successfully.              #切换完成

新slave，3109端显示如下：

#####################输出段4###########################USE ``;SELECT CONNECTION_ID() AS Value;SET wait_timeout=86400;SET GLOBAL read_only=1;                           #将自己设为只读SHOW MASTER STATUS;UNLOCK TABLES;                                    #释放表锁CHANGE MASTER TO MASTER_HOST='192.168.1.110', MASTER_PORT=3110, MASTER_USER='repl', MASTER_PASSWORD='123456', MASTER_AUTO_POSITION=1; #把自己指向MHA选定的新主START SLAVE;SHOW SLAVE STATUS;                                #差异处，启动slave身份SELECT RELEASE_LOCK('MHA_Master_High_Availability_Failover') As Value;   #释放锁止同应用的并发锁

新master，3110端显示如下：

#####################输出段4###########################SHOW SLAVE STATUS;SELECT MASTER_POS_WAIT('3109binlog.000070','536',0) AS Result;      #检查自己是否执行完差异事务STOP SLAVE SQL_THREAD;                                              #停止从库SQL线程SHOW SLAVE STATUS;                                                  SHOW MASTER STATUS;                                                 SELECT @@global.read_only As Value;                                 SELECT @@global.read_only As Value;                                 SET GLOBAL read_only=0;                                             #取消只读状态USE ``;SELECT UNIX_TIMESTAMP();                                            SELECT @@GLOBAL.SERVER_ID;                                          SET @master_heartbeat_period= 30000001024;                          SET @master_binlog_checksum= @@global.binlog_checksum;              SELECT @master_binlog_checksum;                                     SELECT @@GLOBAL.GTID_MODE;                                          SELECT @@GLOBAL.SERVER_UUID;                                        SET @slave_uuid= '28ea40ab-9bbd-11e7-8cd1-000c29c31069';            #写入从库的UUIDSTOP SLAVE;                                                         #停止自身作为从库的身份SHOW SLAVE STATUS;                                              RESET SLAVE /*!50516 ALL */;                                        #清除自身作为从库的所有记录SHOW SLAVE STATUS;SELECT RELEASE_LOCK('MHA_Master_High_Availability_Failover') As Value; #释放锁止同应用的并发锁

看完以上关于使用masterha_master_switch工具实现MySQL高可用MHA的自动切换，很多读者朋友肯定多少有一定的了解，如需获取更多的行业知识信息 ，可以持续关注我们的行业资讯栏目的。