MHAmasterha_check_repl检测过程 - 数据库编程

MHA部署及配置是否OK，我们可以借助于MHA自带的masterha_check_ssh以及masterha_check_repl脚本来检测。masterha_check_repl检测是保证MHA成功切换的重要一步。本文主要描述了masterha_check_repl这个检测脚本到底做了些什么事情。有助于更好的理解MHA的相关原理及过程等。

1、当前的主从环境
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[root@vdbsrv1 ~]# more /etc/hosts
127.0.0.1 localhost.localdomain localhost
192.168.1.6 vdbsrv1 #master
192.168.1.7 vdbsrv2 #slave1
192.168.1.8 vdbsrv3 #slave2
192.168.1.12 vdbsrv4 #manager

###os环境
[root@vdbsrv4 ~]# more /etc/issue
CentOS release 5.9 (Final)
Kernel \r on an \m

###mysql环境
[root@vdbsrv4 ~]# mysql -e "show variables like 'version'"
+---------------+------------+
| Variable_name | Value |
+---------------+------------+
| version | 5.6.22-log |
+---------------+------------+

[root@vdbsrv4 ~]# masterha_manager --version
masterha_manager version 0.56.

2、当前的MHA配置信息
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[root@vdbsrv4 ~]$ more /etc/masterha/app1.cnf
[server default]
manager_workdir=/var/log/masterha/app1
manager_log=/var/log/masterha/app1/manager.log

user=mha
password=xxx
ssh_user=root
repl_user=repl
repl_password=repl
ping_interval=1
shutdown_script=""
master_ip_online_change_script=""
report_script=""
master_ip_failover_script=/tmp/master_ip_failover

[server1]
hostname=vdbsrv1
master_binlog_dir=/data/mysqldata

[server2]
hostname=vdbsrv2
master_binlog_dir=/data/mysqldata

[server3]
hostname=vdbsrv3
master_binlog_dir=/data/mysqldata/
#candidate_master=1

3、masterha_check_repl检测步骤
a、读取配置文件
b、检测配置文件中列出的mysql服务器(识别主从)
c、检测从库配置信息
read_only参数
relay_log_purge参数
复制过滤规则
d、ssh等效性验证
e、检测主库保存binlog脚本(save_binary_logs) ，主要是用于在master死掉后从binlog读取日志
f、检测各从库能否apply差量binlog(apply_diff_relay_logs)
g、检测IP切换，如果有部署脚本

4、实际检测过程
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[root@vdbsrv4 ~]# masterha_check_repl --conf=/etc/masterha/app1.cnf
Fri Apr 17 18:48:41 2015 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Fri Apr 17 18:48:41 2015 - [info] Reading application default configuration from /etc/masterha/app1.cnf..
Fri Apr 17 18:48:41 2015 - [info] Reading server configuration from /etc/masterha/app1.cnf.. ###读取配置文件
Fri Apr 17 18:48:41 2015 - [info] MHA::MasterMonitor version 0.56.
Fri Apr 17 18:48:42 2015 - [info] GTID failover mode = 0
Fri Apr 17 18:48:42 2015 - [info] Dead Servers: ###开始检测配置文件中列出的mysql服务器(识别主从)
Fri Apr 17 18:48:42 2015 - [info] Alive Servers:
Fri Apr 17 18:48:42 2015 - [info] vdbsrv1(192.168.1.6:3306)
Fri Apr 17 18:48:42 2015 - [info] vdbsrv2(192.168.1.7:3306)
Fri Apr 17 18:48:42 2015 - [info] vdbsrv3(192.168.1.8:3306)
Fri Apr 17 18:48:42 2015 - [info] Alive Slaves:
Fri Apr 17 18:48:42 2015 - [info] vdbsrv2(192.168.1.7:3306) Version=5.6.22-log (oldest major version between slaves) log-bin:enabled
Fri Apr 17 18:48:42 2015 - [info] Replicating from 192.168.1.6(192.168.1.6:3306)
Fri Apr 17 18:48:42 2015 - [info] vdbsrv3(192.168.1.8:3306) Version=5.6.22-log (oldest major version between slaves) log-bin:enabled
Fri Apr 17 18:48:42 2015 - [info] Replicating from 192.168.1.6(192.168.1.6:3306)
Fri Apr 17 18:48:42 2015 - [info] Current Alive Master: vdbsrv1(192.168.1.6:3306)
Fri Apr 17 18:48:42 2015 - [info] Checking slave configurations.. ###检测从库配置信息
Fri Apr 17 18:48:42 2015 - [info] read_only=1 is not set on slave vdbsrv2(192.168.1.7:3306).
Fri Apr 17 18:48:42 2015 - [warn

MHAmasterha_check_repl检测过程(一)