最近在研究mysql的高可用架构，自己想总结下常用的高可用方案都有哪些、有哪些优缺点以及应用的场景？搞得是头昏脑涨，天昏地暗，看了诸多资料，每次都觉得公说公有理婆说婆有理。其实嘛，大家说的都有一定的道理，只不过适合自己的才是最正确的。今天就从比较常用的主从+MHA说起。
学习一种新的架构还是软件，最好还是先从了解它的原理开始，这样才能在应用时扬长避短。
一、【MHA原理】
相较于其它HA软件，MHA的目的在于维持MySQL Replication中Master库的高可用性，其最大特点是可以修复多个Slave之间的差异日志，最终使所有Slave保持数据一致，然后从中选择一个充当新的Master，并将其它Slave指向它。
MHA软件由两部分组成，Manager工具包和Node工具包，具体的说明如下。
Manager工具包主要包括以下几个工具：
masterha_check_ssh 检查MHA的SSH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
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）
基本工作流程大致如下：
（1） Manager定期监控Master，监控时间间隔由参数ping_interval决定，缺省为3秒钟一次；可利用其自身的监控功能，也可调用第三方软件来监控；MHA自身提供了两种监控方式：SELECT（执行SELECT 1）和CONNECT（创建连接/断开连接），
主要由ping_type参数决定，默认是select方式。
（2） 当监测到Master故障时，调用SSH脚本对所有Node执行一次检查，包括如下几个方面：
――MySQL实例是否可以连接；
――Master服务器是否可以SSH连通；
――检查SQL Thread的状态；
――检查哪些Server死掉了，哪些Server是活动的，以及活动的Slave实例；
――检查Slave实例的配置及复制过滤规则；
――最后退出监控脚本并返回代表特殊意义代码。
（3） 开始Master故障切换，包括如下几个子阶段：
――Phase 1: Configuration Check Phase
在这个阶段，若某个Slave实例的SQL Thread停止了，则会自动启动它；并再次确认活动的Servers及Slaves。
――Phase 2: Dead Master Shutdown Phase
在这个阶段，首先调用master_ip_failover_script，若HA是基于VIP实现的，则关闭VIP，若是基于目录数据库实现的，则修改映射记录。然后调用shutdown_script脚本强制关闭主机，以避免服务重启时，发生脑裂。
――Phase 3: Master Recovery Phase
又包括如下3个子阶段：
Phase 3.1: Getting Latest Slaves Phase
检查各个Slave，获取最近的和最旧的binary log file和position，并检查各个Slave成为Master的优先级，依赖于candidate_master、no_master、 [server_xxx]顺序、binary log差异量等因素。
Phase 3.2: Saving Dead Master's Binlog Phase
若dead master所在服务器依然可以通过SSH连通，则提取dead master的binary log，提取日志的起点就是上一步获取的最新的binary log file和position，直到最后一条事件日志，并在dead master本地的工作目录（由参数remote_workdir决定）中
创建文件保存这些提取到的日志，然后将该文件拷贝到Manager服务器的工作 目录下（由参数manager_workdir决定）。若dead master系统就无法连接，也就不存在差异的binary log了。MHA还要对各个Slave节点进行健康检查，主要是SSH连通性。
Phase 3.3: Determining New Master Phase
接下来调用apply_diff_relay_logs命令恢复Slave的差异日志，这个差异日志指的是各个Slave之间的relay log。恢复完成后，所有的Slave数据是一致的，此时就可以根据优先级选择New Master了。
Phase 3.4: New Master Diff Log Generation Phase
这里是生成dead master和new master之间的差异日志，即将Phase 3.2保存的binary log拷贝到New Master的工作目录中（remote_workdir）。
Phase 3.5: Master Log Apply Phase
将上一步拷贝的差异日志恢复到New Master上，若发生错误，也可手动恢复。然后获取New Master的binlog name和position，以便其它Slave从这个新的binlog name和position开始复制。最后会开启New Master的写权限，即将read_only参数设置为0。
――Phase 4: Slaves Recovery Phase
Phase 4.1: Starting Parallel Slave Diff Log Generation Phase
生成Slave与New Slave之间的差异日志，并将该日志拷贝到各Slave的工作目录下，这部分日志dead master和new master之间差异的那部分日志，因为各个Slave在Phase 3.3阶段已经同步了。
Phase 4.2: Starting Parallel Slave Log Apply Phase
在各个Slave上应用这部分差异日志，然后通过CHANGE MASTER TO命令将这些Slave指向新的New Master，最后开始复制(start slave)。
――Phase 5: New master cleanup phase
清理New Master其实就是重置slave info，即取消原来的Slave信息。至此整个Master故障切换过程完成。
二、【实验部分】
1、【环境说明】：默认三台机器上都已安装mysql5.6,且主从复制已经配置完成。
角色 主机名 ip地址 功能
主库 node1 192.168.245.129 (w/r) candidate_master node2 192.168.245.131 (r) 从库 node3 192.168.245.132 (r) vip： 192.168.245.100
129为主库，对外提供读写服务，而131和132机器对外提供读服务，需要设置为只读状态，不建议将它写入配置文件，因为从库随时会切换为主库。如下：
set global read_only=1
2、配置三台机器之间的信任机制（省）
目的：机器之间能够无需输入密码进行访问。
3、安装mha软件
- rpm安装：每台机器都要安装node，manager节点建议安装到单独的一台机器上或者一个不用切换为主的从库上
#安装可能需要的依赖包 [root@node1 software]# yum install perl-DBD-MySQL [root@node1 software]# yum install perl-Config-Tiny [root@node1 software]# yum install perl-Parallel-ForkManager*.rpm [root@node1 software]# yum install perl-Mail-Sender*.rpm [root@node1 software]# yum install perl-Mail-Sendmail*.rpm [root@node1 software]# yum install perl-Log-Dispatch*.rpm #安装mha，这里用rpm包安装，默认在/usr/bin [root@node1 software]# yum install mha4mysql-node-0.56-0.el6.noarch.rpm [root@node1 software]# yum install mha4mysql-manager-0.56-0.el6.noarch.rpm
- 二进制包安装
#node安装
wget http://mysql-master-ha.googlecode.com/files/mha4mysql-node-0.53.tar.gz
tar xf mha4mysql-node-0.53.tar.gz
cd mha4mysql-node-0.53
perl Makefile.PL
make && make install
#manager安装
wget http://mysql-master-ha.googlecode.com/files/mha4mysql-manager-0.53.tar.gz
tar xf mha4mysql-manager-0.53.tar.gz
cd mha4mysql-manager-0.53
perl Makefile.PL
make && make install
4、手工配置主库服务器的vip并测试
这里通过脚本手动创建vip，如下：
[root@node1 scripts]# cat init_vip.sh vip="192.168.245.100/32" /sbin/ip addr add $vip dev eth0
【测试】
绑定完成后，可以用以下命令查看绑定情况：
[root@node2 etc]# ip addr show 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:0c:29:d7:0f:4a brd ff:ff:ff:ff:ff:ff inet 192.168.245.131/24 brd 192.168.245.255 scope global eth0 inet 192.168.245.100/32 scope global eth0 inet6 fe80::20c:29ff:fed7:f4a/64 scope link valid_lft forever preferred_lft forever
到任意从库ssh 192.168.245.100 --看是否连上vip或者mysql -h 192.168.245.100 -udarren -pdarren --是否连上vip数据库. 如果都能够连接上，表示vip设置成功了。
5、配置mha及启动
（1）创建mha监控用户（在主库执行，这样每个服务器都有这个用户了）
mysql> grant all privileges on *.* to 'root'@'%' identified by '123456'; Query OK, 0 rows affected (0.00 sec) mysql> flush privileges; Query OK, 0 rows affected (0.01 sec)
（2）关闭purge_relay_logs：
- 在修改配置文件前，注意一个知识点，须将从库上的relay log自动清除设置为OFF，因为MySQL数据库主从复制在缺省情况下从库的relay logs会在SQL线程执行完毕后被自动删除，但是对于MHA场景下，对于某些滞后从库的恢复依赖于其他从库的relay log，因此采取禁用自动删除功能以及定期清理的办法。对于清理过多过大的relay log需要注意引起的复制延迟资源开销等。MHA可通过purge_relay_logs脚本及配合cronjob来完成此项任务。
purge_relay_logs的主要功能：
a、为relay日志创建硬链接(最小化批量删除大文件导致的性能问题)
b、SET GLOBAL relay_log_purge=1; FLUSH LOGS; SET GLOBAL relay_log_purge=0;
c、删除relay log（rm –f /path/to/archive_dir/*）
purge_relay_logs的用法及相关参数 1 purge_relay_logs --help Usage: purge_relay_logs --user=root --password=rootpass --host=127.0.0.1 2 参数描述 --user 用户名，缺省为root --password 密码 --port 端口号 --host 主机名，缺省为127.0.0.1 --workdir 指定创建relay log的硬链接的位置，默认是/var/tmp，成功执行脚本后，硬链接的中继日志文件被删除,由于系统不同分区创建硬链接文件会失败，故需要执行硬链接具体位置，建议指定为relay log相同的分区 --disable_relay_log_purge 默认情况下，如果参数relay_log_purge=1，脚本不做任何处理，自动退出.设定该参数，脚本会将relay_log_purge设置为0，当清理relay log之后，最后将参数设置为OFF(0)
3 定制清理relay log cronjob pureg_relay_logs脚本在不阻塞SQL线程的情况下自动清理relay log。对于不断产生的relay log直接将该脚本部署到crontab以实现按天或按小时定期清理。 $ crontab -l # purge relay logs at 5am 0 5 * * * app /usr/bin/purge_relay_logs --user=root --password=PASSWORD --disable_relay_log_purge >> /var/log/masterha/purge_relay_logs.log 2>&1
- 在我们的两个从库上设置relaylog为OFF:
(product)root@127.0.0.1 [(none)]> set global relay_log_purge=0; Query OK, 0 rows affected (0.00 sec)
- 然后通过定时任务，每隔一天定时清除relaylog：
#清除脚本 #!/bin/bash user=root passwd=root port=3306 log_dir='/data/masterha/log' work_dir='/data' purge='/usr/bin/purge_relay_logs' if [ ! -d $log_dir ] then mkdir $log_dir -p fi $purge --user=$user --password=$passwd --disable_relay_log_purge --port=$port --workdir=$work_dir >> $log_dir/purge_relay_logs.log 2>&1 #定时任务 crontab -e #每天早上5点10分执行 10 5 * * * sh /data/scripts/purge_relay_log.sh
（3）修改配置文件：
到manager节点的/etc下面新建masterha目录，并将mha需要的配置初始化文件拷贝到该目录下：
[root@node3 ~]# cd /etc
[root@node3 etc]# mkdir masterha
#创建以下mha日志目录，没有则报错
[root@node3 etc]#mkdir -p /var/log/masterha/app1
[root@node3 mastermha]# ll
total 32
-rw-r--r--. 1 root root 503 Nov 9 01:26 app1.conf
-rwxr-xr-x. 1 root root 55 Nov 9 01:26 drop_vip.sh
-rwxr-xr-x. 1 root root 55 Nov 9 01:26 init_vip.sh
-rw-r--r--. 1 root root 357 Nov 9 01:26 masterha_default.conf
-rwxr-xr-x. 1 root root 3888 Nov 9 01:26 master_ip_failover
-rwxr-xr-x. 1 root root 10298 Nov 9 01:26 master_ip_online_change
然后修改vip的值：在masterha目录下执行grep "vip" *,将会列出所有文件中vip变量，然后一一修改为192.168.245.100。
修改app1.conf文件：
[server default]
manager_log=/var/log/masterha/app1/app1.log
manager_workdir=/var/log/masterha/app1
master_ip_failover_script="/etc/masterha/master_ip_failover"
master_ip_online_change_script="/etc/masterha/master_ip_online_change"
password=root
ping_interval=1
remote_workdir=/var/log/masterha/app1
repl_password=repl4slave
repl_user=repl
report_script="/etc/masterha/send_mail"
shutdown_script=""
ssh_user=root
user=root
[server1]
candidate_master=1
check_repl_delay=0
hostname=192.168.245.129
master_binlog_dir=/data/mysql/mysql_3306/logs
[server3]
hostname=192.168.245.132
port=3306
（4）检查mha环境并启动
#检查MHA Manger到所有MHA Node的SSH连接状态： [root@node3 masterha]# /usr/bin/masterha_check_ssh --conf=/etc/masterha/app1.conf Mon Nov 16 01:24:21 2015 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping. Mon Nov 16 01:24:21 2015 - [info] Reading application default configuration from /etc/masterha/app1.conf.. Mon Nov 16 01:24:21 2015 - [info] Reading server configuration from /etc/masterha/app1.conf.. Mon Nov 16 01:24:21 2015 - [info] Starting SSH connection tests.. Mon Nov 16 01:24:24 2015 - [debug] Mon Nov 16 01:24:21 2015 - [debug] Connecting via SSH from root@192.168.245.129(192.168.245.129:22) to root@192.168.245.131(192.168.245.131:22).. Mon Nov 16 01:24:23 2015 - [debug] ok. Mon Nov 16 01:24:23 2015 - [debug] Connecting via SSH from root@192.168.245.129(192.168.245.129:22) to root@192.168.245.132(192.168.245.132:22).. Mon Nov 16 01:24:24 2015 - [debug] ok. Mon Nov 16 01:24:25 2015 - [debug] Mon Nov 16 01:24:22 2015 - [debug] Connecting via SSH from root@192.168.245.131(192.168.245.131:22) to root@192.168.245.129(192.168.245.129:22).. Mon Nov 16 01:24:23 2015 - [debug] ok. Mon Nov 16 01:24:23 2015 - [debug] Connecting via SSH from root@192.168.245.131(192.168.245.131:22) to root@192.168.245.132(192.168.245.132:22).. Mon Nov 16 01:24:25 2015 - [debug] ok. Mon Nov 16 01:24:25 2015 - [debug] Mon Nov 16 01:24:22 2015 - [debug] Connecting via SSH from root@192.168.245.132(192.168.245.132:22) to root@192.168.245.129(192.168.245.129:22).. Mon Nov 16 01:24:24 2015 - [debug] ok. Mon Nov 16 01:24:24 2015 - [debug] Connecting via SSH from root@192.168.245.132(192.168.245.132:22) to root@192.168.245.131(192.168.245.131:22).. Mon Nov 16 01:24:25 2015 - [debug] ok. Mon Nov 16 01:24:25 2015 - [info] All SSH connection tests passed successfully.
#检查主从复制环境 [root@node3 masterha]# /usr/bin/masterha_check_repl --conf=/etc/masterha/app1.conf Mon Nov 16 01:37:08 2015 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping. Mon Nov 16 01:37:08 2015 - [info] Reading application default configuration from /etc/masterha/app1.conf.. Mon Nov 16 01:37:08 2015 - [info] Reading server configuration from /etc/masterha/app1.conf.. Mon Nov 16 01:37:08 2015 - [info] MHA::MasterMonitor version 0.56. Mon Nov 16 01:37:09 2015 - [info] GTID failover mode = 0 Mon Nov 16 01:37:09 2015 - [info] Dead Servers: Mon Nov 16 01:37:09 2015 - [info] Alive Servers: Mon Nov 16 01:37:09 2015 - [info] 192.168.245.129(192.168.245.129:3306) Mon Nov 16 01:37:09 2015 - [info] 192.168.245.131(192.168.245.131:3306) Mon Nov 16 01:37:09 2015 - [info] 192.168.245.132(192.168.245.132:3306) Mon Nov 16 01:37:09 2015 - [info] Alive Slaves: Mon Nov 16 01:37:09 2015 - [info] 192.168.245.131(192.168.245.131:3306) Version=5.6.23-log (oldest major version between slaves) log-bin:enabled Mon Nov 16 01:37:09 2015 - [info] Replicating from 192.168.245.129(192.168.245.129:3306) Mon Nov 16 01:37:09 2015 - [info] Primary candidate for the new Master (candidate_master is set) Mon Nov 16 01:37:09 2015 - [info] 192.168.245.132(192.168.245.132:3306) Version=5.6.21-log (oldest major version between slaves) log-bin:enabled Mon Nov 16 01:37:09 2015 - [info] Replicating from 192.168.245.129(192.168.245.129:3306) Mon Nov 16 01:37:09 2015 - [info] Current Alive Master: 192.168.245.129(192.168.245.129:3306) Mon Nov 16 01:37:09 2015 - [info] Checking slave configurations.. Mon Nov 16 01:37:09 2015 - [info] read_only=1 is not set on slave 192.168.245.131(192.168.245.131:3306). Mon Nov 16 01:37:09 2015 - [info] read_only=1 is not set on slave 192.168.245.132(192.168.245.132:3306). Mon Nov 16 01:37:09 2015 - [info] Checking replication filtering settings.. Mon Nov 16 01:37:09 2015 - [info] binlog_do_db= , binlog_ignore_db= Mon Nov 16 01:37:09 2015 - [info] Replication filtering check ok. Mon Nov 16 01:37:09 2015 - [info] GTID (with auto-pos) is not supported Mon Nov 16 01:37:09 2015 - [info] Starting SSH connection tests.. Mon Nov 16 01:37:12 2015 - [info] All SSH connection tests passed successfully. Mon Nov 16 01:37:12 2015 - [info] Checking MHA Node version.. Mon Nov 16 01:37:13 2015 - [info] Version check ok. Mon Nov 16 01:37:13 2015 - [info] Checking SSH publickey authentication settings on the current master.. Mon Nov 16 01:37:13 2015 - [info] HealthCheck: SSH to 192.168.245.129 is reachable. Mon Nov 16 01:37:14 2015 - [info] Master MHA Node version is 0.56. Mon Nov 16 01:37:14 2015 - [info] Checking recovery script configurations on 192.168.245.129(192.168.245.129:3306).. Mon Nov 16 01:37:14 2015 - [info] Executing command: save_binary_logs --command=test --start_pos=4 --binlog_dir=/data/mysql/mysql_3306/logs --output_file=/var/log/masterha/app1/save_binary_logs_test --manager_version=0.56 --start_file=mysql-bin.000023 Mon Nov 16 01:37:14 2015 - [info] Connecting to root@192.168.245.129(192.168.245.129:22).. Creating /var/log/masterha/app1 if not exists.. ok. Checking output directory is accessible or not.. ok. Binlog found at /data/mysql/mysql_3306/logs, up to mysql-bin.000023 Mon Nov 16 01:37:15 2015 - [info] Binlog setting check done. Mon Nov 16 01:37:15 2015 - [info] Checking SSH publickey authentication and checking recovery script configurations on all alive slave servers.. Mon Nov 16 01:37:15 2015 - [info] Executing command : apply_diff_relay_logs --command=test --slave_user='root' --slave_host=192.168.245.131 --slave_ip=192.168.245.131 --slave_port=3306 --workdir=/var/log/masterha/app1 --target_version=5.6.23-log --manager_version=0.56 --relay_log_info=/data/mysql/mysql_3306/data/relay-log.info --relay_dir=/data/mysql/mysql_3306/data/ --slave_pass=xxx Mon Nov 16 01:37:15 2015 - [info] Connecting to root@192.168.245.131(192.168.245.131:22).. Checking slave recovery environment settings.. Opening /data/mysql/mysql_3306/data/relay-log.info ... ok. Relay log found at /data/mysql/mysql_3306/data, up to relay-bin.000009 Temporary relay log file is /data/mysql/mysql_3306/data/relay-bin.000009 Testing mysql connection and privileges..Warning: Using a password on the command line interface can be insecure. done. Testing mysqlbinlog output.. done. Cleaning up test file(s).. done. Mon Nov 16 01:37:15 2015 - [info] Executing command : apply_diff_relay_logs --command=test --slave_user='root' --slave_host=192.168.245.132 --slave_ip=192.168.245.132 --slave_port=3306 --workdir=/var/log/masterha/app1 --target_version=5.6.21-log --manager_version=0.56 --relay_log_info=/data/mysql/data/relay-log.info --relay_dir=/data/mysql/data/ --slave_pass=xxx Mon Nov 16 01:37:15 2015 - [info] Connecting to root@192.168.245.132(192.168.245.132:22).. Checking slave recovery environment settings.. Opening /data/mysql/data/relay-log.info ... ok. Relay log found at /data/mysql/data, up to node3-relay-bin.000007 Temporary relay log file is /data/mysql/data/node3-relay-bin.000007 Testing mysql connection and privileges..Warning: Using a password on the command line interface can be insecure. done. Testing mysqlbinlog output.. done. Cleaning up test file(s).. done. Mon Nov 16 01:37:16 2015 - [info] Slaves settings check done. Mon Nov 16 01:37:16 2015 - [info] 192.168.245.129(192.168.245.129:3306) (current master) +--192.168.245.131(192.168.245.131:3306) +--192.168.245.132(192.168.245.132:3306) Mon Nov 16 01:37:16 2015 - [info] Checking replication health on 192.168.245.131.. Mon Nov 16 01:37:16 2015 - [info] ok. Mon Nov 16 01:37:16 2015 - [info] Checking replication health on 192.168.245.132.. Mon Nov 16 01:37:16 2015 - [info] ok. Mon Nov 16 01:37:16 2015 - [warning] master_ip_failover_script is not defined. Mon Nov 16 01:37:16 2015 - [warning] shutdown_script is not defined. Mon Nov 16 01:37:16 2015 - [info] Got exit code 0 (Not master dead). MySQL Replication Health is OK.
如果遇到这个报错：
Can't exec "mysqlbinlog": No such file or directory at /usr/share/perl5/vendor_perl/MHA/BinlogManager.pm line 106. mysqlbinlog version command failed with rc 1:0, please verify PATH, LD_LIBRARY_PATH, and client options at /usr/bin/apply_diff_relay_logs line 493 Mon Nov 16 01:32:36 2015 - [error][/usr/share/perl5/vendor_perl/MHA/MasterMonitor.pm, ln205] Slaves settings check failed! Mon Nov 16 01:32:36 2015 - [error][/usr/share/perl5/vendor_perl/MHA/MasterMonitor.pm, ln413] Slave configuration failed. Mon Nov 16 01:32:36 2015 - [error][/usr/share/perl5/vendor_perl/MHA/MasterMonitor.pm, ln424] Error happened on checking configurations. at /usr/bin/masterha_check_repl line 48 Mon Nov 16 01:32:36 2015 - [error][/usr/share/perl5/vendor_perl/MHA/MasterMonitor.pm, ln523] Error happened on monitoring servers. Mon Nov 16 01:32:36 2015 - [info] Got exit code 1 (Not master dead). MySQL Replication Health is NOT OK!
解决方法如下，添加软连接（所有节点）
ln -s /usr/local/mysql/bin/mysqlbinlog /usr/local/bin/mysqlbinlog
ln -s /usr/local/mysql/bin/mysql /usr/local/bin/mysql
到此为止，都没问题了，开始启动manager节点进行监控，一般启动我们都使用nohup方式，但是当出现故障成功切换后，manager监控也会关闭，所以建议使用daemontools方式在后台运行。
- nohup方式启动
nohup /usr/bin/masterha_manager --conf=/etc/masterha/app1.conf --remove_dead_master_conf --ignore_last_failover &
#关闭mha监控
/usr/bin/masterha_stop --conf=/etc/masterha/app1.conf
- daemontools方式启动：
#下载daemontools工具 wget http://cr.yp.to/daemontools/daemontools-0.76.tar.gz #安装 cd /home/software/daemontools/admin/daemontools-0.76 vim src/conf-cc #在第一行最后空一格后添加 -include /usr/include/errno.h 避免编译时报错 package/install #安装 #在/etc/init/创建svscan.conf文件并添加如下内容： vim /etc/init/svscan.conf start on runlevel [345] respawn exec /command/svscanboot #在/etc/init目录下重新加载并启动 [root@node3 init]# initctl reload-configuration [root@node3 init]# initctl start svscan svscan start/running, process 17002
使用daemon启动mha监控：
[root@node3 init]# mkdir -p /service/masterha_app [root@node3 ~]# cd /service/masterha_app/ [root@node3 masterha_app]# pwd /service/masterha_app #在/service/masterha_app/创建run脚本并增加执行权限，内容如下 [root@node3 masterha_app]# cat /service/masterha_app/run #!/bin/bash exec /usr/bin/masterha_manager --conf=/etc/masterha/app1.conf --remove_dead_master_conf --ignore_last_failover
[root@node3 masterha_app]# chmod +x /service/masterha_app/run
#停止监控
svc -d /service/masterha_app
#开启监控
svc -u /service/masterha_app
另起一个session，查看启动日志：
[root@node3 app1]# tail -f app1.log 192.168.245.129(192.168.245.129:3306) (current master) +--192.168.245.131(192.168.245.131:3306) +--192.168.245.132(192.168.245.132:3306) Mon Nov 16 01:55:10 2015 - [warning] master_ip_failover_script is not defined. Mon Nov 16 01:55:10 2015 - [warning] shutdown_script is not defined. Mon Nov 16 01:55:10 2015 - [info] Set master ping interval 1 seconds. Mon Nov 16 01:55:10 2015 - [warning] secondary_check_script is not defined. It is highly recommended setting it to check master reachability from two or more routes. Mon Nov 16 01:55:10 2015 - [info] Starting ping health check on 192.168.245.129(192.168.245.129:3306).. Mon Nov 16 01:55:10 2015 - [info] Ping(SELECT) succeeded, waiting until MySQL doesn't respond..
当看到最后一句“Ping(SELECT) succeeded, waiting until MySQL doesn't respond..”表示mha已经启动起来了。当然，你或许在一台机子上希望监控多套master-salve复制，这非常容易，只要为第二套集群创建一个新的配置文件并启动manager
# masterha_manager --conf=/etc/conf/masterha/app1.cnf
# masterha_manager --conf=/etc/conf/masterha/app2.cnf
如果你在app1和app2上有一些共有的参数，可在全局配置文件中配置。
启动参数介绍：
--remove_dead_master_conf 该参数表示当发生主从切换后，老的主库的ip将会从配置文件中移除。如果故障机器修复好了，需要手工添加ip信息到配置文件中
--manger_log 日志存放位置
--ignore_last_failover 在缺省情况下，如果MHA检测到连续发生宕机，且两次宕机间隔不足8小时的话，则不会进行Failover，之所以这样限制是为了避免ping-pong效应。该参数代表忽略上次MHA触发切换产生的文件， 默认情况下，MHA发生切换后会在日志目录，也就是上面我设置的/data产生app1.failover.complete文件，下次再次切换的时候如 果发现该目录下存在该文件将不允许触发切换，除非在第一次切换后收到删除该文件，为了方便，这里设置为--ignore_last_failover。
查看MHA Manager监控是否正常：
[root@node3 app1]# /usr/bin/masterha_check_status --conf=/etc/masterha/app1.conf app1 (pid:6795) is running(0:PING_OK), master:192.168.245.129
6、模拟测试
（1）自动Failover测试
- 首先用sysbench工具模拟主库业务的写入。
#下载sysbench http://dev.mysql.com/downloads/benchmarks.html #安装sysbench yum install libtool -y #依赖包 tar zxvf sysbench-0.4.12.7.tar.gz cd sysbench-0.4.12.7 ./configure && make && make install
在主库执行，创建sysbench测试表：
(product)root@127.0.0.1 [(none)]> create database sbtest; Query OK, 1 row affected (0.00 sec) [root@node1 sysbench-0.4.12.7]# /usr/local/bin/sysbench --test=oltp --oltp-table-size=100000 --oltp-read-only=off --init-rng=on --num-threads=4 --max-requests=0 --oltp-dist-type=uniform --max-time=1800 --mysql-user=root --mysql-socket=/tmp/mysql_3306.sock --mysql-password=root --mysql-host=192.168.245.129 --db-driver=mysql --mysql-table-engine=innodb --oltp-test-mode=complex prepare sysbench 0.4.12.6: multi-threaded system evaluation benchmark Creating table 'sbtest'... Creating 100000 records in table 'sbtest'...
- 停止接管主库那个从库的io_thread线程：
(product)root@127.0.0.1 [(none)]> stop slave io_thread; Query OK, 0 rows affected (0.01 sec)
- 向主库插入数据：
[root@node1 sysbench-0.4.12.7]# /usr/local/bin/sysbench --test=oltp --oltp-table-size=100000 --oltp-read-only=off --init-rng=on --num-threads=4 --max-requests=0 --oltp-dist-type=uniform --max-time=180 --mysql-user=root --mysql-socket=/tmp/mysql_3306.sock --mysql-password=root --mysql-host=192.168.245.129 --db-driver=mysql --mysql-table-engine=innodb --oltp-test-mode=complex run sysbench 0.4.12.6: multi-threaded system evaluation benchmark Running the test with following options: Number of threads: 4 Initializing random number generator from timer. Random number generator seed is 0 and will be ignored Doing OLTP test. Running mixed OLTP test Using Uniform distribution Using "BEGIN" for starting transactions Using auto_inc on the id column Using 1 test tables Threads started! Time limit exceeded, exiting... (last message repeated 3 times) Done. OLTP test statistics: queries performed: read: 489090 write: 174675 other: 69870 total: 733635 transactions: 34935 (194.05 per sec.) deadlocks: 0 (0.00 per sec.) read/write requests: 663765 (3686.93 per sec.) other operations: 69870 (388.10 per sec.) Test execution summary: total time: 180.0317s total number of events: 34935 total time taken by event execution: 719.7722 per-request statistics: min: 3.47ms avg: 20.60ms max: 444.43ms approx. 95 percentile: 28.17ms Threads fairness: events (avg/stddev): 8733.7500/260.92 execution time (avg/stddev): 179.9430/0.01
然后启动从库上io_thread:
(product)root@127.0.0.1 [(none)]> start slave io_thread; Query OK, 0 rows affected, 1 warning (0.00 sec)
- kill主库的mysqld：
pkill -9 mysqld
最后，查看mha日志，这时已经接管过来了！
Mon Nov 16 02:07:11 2015 - [warning] master_ip_failover_script is not defined. Mon Nov 16 02:07:11 2015 - [warning] shutdown_script is not defined. Mon Nov 16 02:07:11 2015 - [info] Set master ping interval 1 seconds. Mon Nov 16 02:07:11 2015 - [warning] secondary_check_script is not defined. It is highly recommended setting it to check master reachability from two or more routes. Mon Nov 16 02:07:11 2015 - [info] Starting ping health check on 192.168.245.129(192.168.245.129:3306).. Mon Nov 16 02:07:11 2015 - [info] Ping(SELECT) succeeded, waiting until MySQL doesn't respond.. Mon Nov 16 03:02:12 2015 - [warning] Got error on MySQL select ping: 2006 (MySQL server has gone away) Mon Nov 16 03:02:12 2015 - [info] Executing SSH check script: save_binary_logs --command=test --start_pos=4 --binlog_dir=/data/mysql/mysql_3306/logs --output_file=/var/log/masterha/app1/save_binary_logs_test --manager_version=0.56 --binlog_prefix=mysql-bin Mon Nov 16 03:02:13 2015 - [info] HealthCheck: SSH to 192.168.245.129 is reachable. Mon Nov 16 03:02:13 2015 - [warning] Got error on MySQL connect: 2013 (Lost connection to MySQL server at 'reading initial communication packet', system error: 111) Mon Nov 16 03:02:13 2015 - [warning] Connection failed 2 time(s).. Mon Nov 16 03:02:14 2015 - [warning] Got error on MySQL connect: 2013 (Lost connection to MySQL server at 'reading initial communication packet', system error: 111) Mon Nov 16 03:02:14 2015 - [warning] Connection failed 3 time(s).. Mon Nov 16 03:02:15 2015 - [warning] Got error on MySQL connect: 2013 (Lost connection to MySQL server at 'reading initial communication packet', system error: 111) Mon Nov 16 03:02:15 2015 - [warning] Connection failed 4 time(s).. Mon Nov 16 03:02:15 2015 - [warning] Master is not reachable from health checker! Mon Nov 16 03:02:15 2015 - [warning] Master 192.168.245.129(192.168.245.129:3306) is not reachable! Mon Nov 16 03:02:15 2015 - [warning] SSH is reachable. Mon Nov 16 03:02:15 2015 - [info] Connecting to a master server failed. Reading configuration file /etc/masterha_default.cnf and /etc/masterha/app1.conf again, and trying to connect to all servers to check server status.. Mon Nov 16 03:02:15 2015 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping. Mon Nov 16 03:02:15 2015 - [info] Reading application default configuration from /etc/masterha/app1.conf.. Mon Nov 16 03:02:15 2015 - [info] Reading server configuration from /etc/masterha/app1.conf.. Mon Nov 16 03:02:15 2015 - [info] GTID failover mode = 0 Mon Nov 16 03:02:15 2015 - [info] Dead Servers: Mon Nov 16 03:02:15 2015 - [info] 192.168.245.129(192.168.245.129:3306) Mon Nov 16 03:02:15 2015 - [info] Alive Servers: Mon Nov 16 03:02:15 2015 - [info] 192.168.245.131(192.168.245.131:3306) Mon Nov 16 03:02:15 2015 - [info] 192.168.245.132(192.168.245.132:3306) Mon Nov 16 03:02:15 2015 - [info] Alive Slaves: Mon Nov 16 03:02:15 2015 - [info] 192.168.245.131(192.168.245.131:3306) Version=5.6.23-log (oldest major version between slaves) log-bin:enabled Mon Nov 16 03:02:15 2015 - [info] Replicating from 192.168.245.129(192.168.245.129:3306) Mon Nov 16 03:02:15 2015 - [info] Primary candidate for the new Master (candidate_master is set) Mon Nov 16 03:02:15 2015 - [info] 192.168.245.132(192.168.245.132:3306) Version=5.6.21-log (oldest major version between slaves) log-bin:enabled Mon Nov 16 03:02:15 2015 - [info] Replicating from 192.168.245.129(192.168.245.129:3306) Mon Nov 16 03:02:15 2015 - [info] Checking slave configurations.. Mon Nov 16 03:02:15 2015 - [info] read_only=1 is not set on slave 192.168.245.131(192.168.245.131:3306). Mon Nov 16 03:02:15 2015 - [info] read_only=1 is not set on slave 192.168.245.132(192.168.245.132:3306). Mon Nov 16 03:02:15 2015 - [info] Checking replication filtering settings.. Mon Nov 16 03:02:15 2015 - [info] Replication filtering check ok. Mon Nov 16 03:02:15 2015 - [info] Master is down! Mon Nov 16 03:02:15 2015 - [info] Terminating monitoring script. Mon Nov 16 03:02:15 2015 - [info] Got exit code 20 (Master dead). Mon Nov 16 03:02:15 2015 - [info] MHA::MasterFailover version 0.56. Mon Nov 16 03:02:15 2015 - [info] Starting master failover. Mon Nov 16 03:02:15 2015 - [info] Mon Nov 16 03:02:15 2015 - [info] * Phase 1: Configuration Check Phase.. Mon Nov 16 03:02:15 2015 - [info] Mon Nov 16 03:02:16 2015 - [info] GTID failover mode = 0 Mon Nov 16 03:02:16 2015 - [info] Dead Servers: Mon Nov 16 03:02:16 2015 - [info] 192.168.245.129(192.168.245.129:3306) Mon Nov 16 03:02:16 2015 - [info] Checking master reachability via MySQL(double check)... Mon Nov 16 03:02:16 2015 - [info] ok. Mon Nov 16 03:02:16 2015 - [info] Alive Servers: Mon Nov 16 03:02:16 2015 - [info] 192.168.245.131(192.168.245.131:3306) Mon Nov 16 03:02:16 2015 - [info] 192.168.245.132(192.168.245.132:3306) Mon Nov 16 03:02:16 2015 - [info] Alive Slaves: Mon Nov 16 03:02:16 2015 - [info] 192.168.245.131(192.168.245.131:3306) Version=5.6.23-log (oldest major version between slaves) log-bin:enabled Mon Nov 16 03:02:16 2015 - [info] Replicating from 192.168.245.129(192.168.245.129:3306) Mon Nov 16 03:02:16 2015 - [info] Primary candidate for the new Master (candidate_master is set) Mon Nov 16 03:02:16 2015 - [info] 192.168.245.132(192.168.245.132:3306) Version=5.6.21-log (oldest major version between slaves) log-bin:enabled Mon Nov 16 03:02:16 2015 - [info] Replicating from 192.168.245.129(192.168.245.129:3306) Mon Nov 16 03:02:16 2015 - [info] Starting Non-GTID based failover. Mon Nov 16 03:02:16 2015 - [info] Mon Nov 16 03:02:16 2015 - [info] ** Phase 1: Configuration Check Phase completed. Mon Nov 16 03:02:16 2015 - [info] Mon Nov 16 03:02:16 2015 - [info] * Phase 2: Dead Master Shutdown Phase.. Mon Nov 16 03:02:16 2015 - [info] Mon Nov 16 03:02:16 2015 - [info] Forcing shutdown so that applications never connect to the current master.. Mon Nov 16 03:02:16 2015 - [warning] master_ip_failover_script is not set. Skipping invalidating dead master IP address. Mon Nov 16 03:02:16 2015 - [warning] shutdown_script is not set. Skipping explicit shutting down of the dead master. Mon Nov 16 03:02:16 2015 - [info] * Phase 2: Dead Master Shutdown Phase completed. Mon Nov 16 03:02:16 2015 - [info] Mon Nov 16 03:02:16 2015 - [info] * Phase 3: Master Recovery Phase.. Mon Nov 16 03:02:16 2015 - [info] Mon Nov 16 03:02:16 2015 - [info] * Phase 3.1: Getting Latest Slaves Phase.. Mon Nov 16 03:02:16 2015 - [info] Mon Nov 16 03:02:16 2015 - [info] The latest binary log file/position on all slaves is mysql-bin.000023:35416929 Mon Nov 16 03:02:16 2015 - [info] Latest slaves (Slaves that received relay log files to the latest): Mon Nov 16 03:02:16 2015 - [info] 192.168.245.131(192.168.245.131:3306) Version=5.6.23-log (oldest major version between slaves) log-bin:enabled Mon Nov 16 03:02:16 2015 - [info] Replicating from 192.168.245.129(192.168.245.129:3306) Mon Nov 16 03:02:16 2015 - [info] Primary candidate for the new Master (candidate_master is set) Mon Nov 16 03:02:16 2015 - [info] 192.168.245.132(192.168.245.132:3306) Version=5.6.21-log (oldest major version between slaves) log-bin:enabled Mon Nov 16 03:02:16 2015 - [info] Replicating from 192.168.245.129(192.168.245.129:3306) Mon Nov 16 03:02:16 2015 - [info] The oldest binary log file/position on all slaves is mysql-bin.000023:35416929 Mon Nov 16 03:02:16 2015 - [info] Oldest slaves: Mon Nov 16 03:02:16 2015 - [info] 192.168.245.131(192.168.245.131:3306) Version=5.6.23-log (oldest major version between slaves) log-bin:enabled Mon Nov 16 03:02:16 2015 - [info] Replicating from 192.168.245.129(192.168.245.129:3306) Mon Nov 16 03:02:16 2015 - [info] Primary candidate for the new Master (candidate_master is set) Mon Nov 16 03:02:16 2015 - [info] 192.168.245.132(192.168.245.132:3306) Version=5.6.21-log (oldest major version between slaves) log-bin:enabled Mon Nov 16 03:02:16 2015 - [info] Replicating from 192.168.245.129(192.168.245.129:3306) Mon Nov 16 03:02:16 2015 - [info] Mon Nov 16 03:02:16 2015 - [info] * Phase 3.2: Saving Dead Master's Binlog Phase.. Mon Nov 16 03:02:16 2015 - [info] Mon Nov 16 03:02:17 2015 - [info] Fetching dead master's binary logs.. Mon Nov 16 03:02:17 2015 - [info] Executing command on the dead master 192.168.245.129(192.168.245.129:3306): save_binary_logs --command=save --start_file=mysql-bin.000023 --start_pos=35416929 --binlog_dir=/data/mysql/mysql_3306/logs --output_file=/var/log/masterha/app 1/saved_master_binlog_from_192.168.245.129_3306_20151116030215.binlog --handle_raw_binlog=1 --disable_log_bin=0 --manager_version=0.56 Creating /var/log/masterha/app1 if not exists.. ok. Concat binary/relay logs from mysql-bin.000023 pos 35416929 to mysql-bin.000023 EOF into /var/log/masterha/app1/saved_master_binlog_from_192.168.245.129_3306_20151116030215.binlog .. Binlog Checksum enabled Dumping binlog format description event, from position 0 to 120.. ok. No need to dump effective binlog data from /data/mysql/mysql_3306/logs/mysql-bin.000023 (pos starts 35416929, filesize 35416929). Skipping. Binlog Checksum enabled /var/log/masterha/app1/saved_master_binlog_from_192.168.245.129_3306_20151116030215.binlog has no effective data events. Event not exists. Mon Nov 16 03:02:18 2015 - [info] Additional events were not found from the orig master. No need to save. Mon Nov 16 03:02:18 2015 - [info] Mon Nov 16 03:02:18 2015 - [info] * Phase 3.3: Determining New Master Phase.. Mon Nov 16 03:02:18 2015 - [info] Mon Nov 16 03:02:18 2015 - [info] Finding the latest slave that has all relay logs for recovering other slaves.. Mon Nov 16 03:02:18 2015 - [info] All slaves received relay logs to the same position. No need to resync each other. Mon Nov 16 03:02:18 2015 - [info] Searching new master from slaves.. Mon Nov 16 03:02:18 2015 - [info] Candidate masters from the configuration file: Mon Nov 16 03:02:18 2015 - [info] 192.168.245.131(192.168.245.131:3306) Version=5.6.23-log (oldest major version between slaves) log-bin:enabled Mon Nov 16 03:02:18 2015 - [info] Replicating from 192.168.245.129(192.168.245.129:3306) Mon Nov 16 03:02:18 2015 - [info] Primary candidate for the new Master (candidate_master is set) Mon Nov 16 03:02:18 2015 - [info] Non-candidate masters: Mon Nov 16 03:02:18 2015 - [info] Searching from candidate_master slaves which have received the latest relay log events.. Mon Nov 16 03:02:18 2015 - [info] New master is 192.168.245.131(192.168.245.131:3306) Mon Nov 16 03:02:18 2015 - [info] Starting master failover.. Mon Nov 16 03:02:18 2015 - [info] From: 192.168.245.129(192.168.245.129:3306) (current master) +--192.168.245.131(192.168.245.131:3306) +--192.168.245.132(192.168.245.132:3306) To: 192.168.245.131(192.168.245.131:3306) (new master) +--192.168.245.132(192.168.245.132:3306) Mon Nov 16 03:02:18 2015 - [info] Mon Nov 16 03:02:18 2015 - [info] * Phase 3.3: New Master Diff Log Generation Phase.. Mon Nov 16 03:02:18 2015 - [info] Mon Nov 16 03:02:18 2015 - [info] This server has all relay logs. No need to generate diff files from the latest slave. Mon Nov 16 03:02:18 2015 - [info] Mon Nov 16 03:02:18 2015 - [info] * Phase 3.4: Master Log Apply Phase.. Mon Nov 16 03:02:18 2015 - [info] Mon Nov 16 03:02:18 2015 - [info] *NOTICE: If any error happens from this phase, manual recovery is needed. Mon Nov 16 03:02:18 2015 - [info] Starting recovery on 192.168.245.131(192.168.245.131:3306).. Mon Nov 16 03:02:18 2015 - [info] This server has all relay logs. Waiting all logs to be applied.. Mon Nov 16 03:02:20 2015 - [info] done. Mon Nov 16 03:02:20 2015 - [info] All relay logs were successfully applied. Mon Nov 16 03:02:20 2015 - [info] Getting new master's binlog name and position.. Mon Nov 16 03:02:20 2015 - [info] mysql-bin.000013:35416929 Mon Nov 16 03:02:20 2015 - [info] All other slaves should start replication from here. Statement should be: CHANGE MASTER TO MASTER_HOST='192.168.245.131', MASTER_PORT=3306, MASTER_LOG_FILE='mysql-bin.000013', MASTER_LOG_POS=35416929, MASTER_USER='repl', MASTER_PASSWOR D='xxx'; Mon Nov 16 03:02:20 2015 - [warning] master_ip_failover_script is not set. Skipping taking over new master IP address. Mon Nov 16 03:02:20 2015 - [info] ** Finished master recovery successfully. Mon Nov 16 03:02:20 2015 - [info] * Phase 3: Master Recovery Phase completed. Mon Nov 16 03:02:20 2015 - [info] Mon Nov 16 03:02:20 2015 - [info] * Phase 4: Slaves Recovery Phase.. Mon Nov 16 03:02:20 2015 - [info] Mon Nov 16 03:02:20 2015 - [info] * Phase 4.1: Starting Parallel Slave Diff Log Generation Phase.. Mon Nov 16 03:02:20 2015 - [info] Mon Nov 16 03:02:20 2015 - [info] -- Slave diff file generation on host 192.168.245.132(192.168.245.132:3306) started, pid: 10508. Check tmp log /var/log/masterha/app1/192.168.245.132_3306_20151116030215.log if it takes time.. Mon Nov 16 03:02:20 2015 - [info] Mon Nov 16 03:02:20 2015 - [info] Log messages from 192.168.245.132 ... Mon Nov 16 03:02:20 2015 - [info] Mon Nov 16 03:02:20 2015 - [info] This server has all relay logs. No need to generate diff files from the latest slave. Mon Nov 16 03:02:20 2015 - [info] End of log messages from 192.168.245.132. Mon Nov 16 03:02:20 2015 - [info] -- 192.168.245.132(192.168.245.132:3306) has the latest relay log events. Mon Nov 16 03:02:20 2015 - [info] Generating relay diff files from the latest slave succeeded. Mon Nov 16 03:02:20 2015 - [info] Mon Nov 16 03:02:20 2015 - [info] * Phase 4.2: Starting Parallel Slave Log Apply Phase.. Mon Nov 16 03:02:20 2015 - [info] Mon Nov 16 03:02:20 2015 - [info] -- Slave recovery on host 192.168.245.132(192.168.245.132:3306) started, pid: 10510. Check tmp log /var/log/masterha/app1/192.168.245.132_3306_20151116030215.log if it takes time.. Mon Nov 16 03:02:20 2015 - [info] Mon Nov 16 03:02:20 2015 - [info] Log messages from 192.168.245.132 ... Mon Nov 16 03:02:20 2015 - [info] Mon Nov 16 03:02:20 2015 - [info] Starting recovery on 192.168.245.132(192.168.245.132:3306).. Mon Nov 16 03:02:20 2015 - [info] This server has all relay logs. Waiting all logs to be applied.. Mon Nov 16 03:02:20 2015 - [info] done. Mon Nov 16 03:02:20 2015 - [info] All relay logs were successfully applied. Mon Nov 16 03:02:20 2015 - [info] Resetting slave 192.168.245.132(192.168.245.132:3306) and starting replication from the new master 192.168.245.131(192.168.245.131:3306).. Mon Nov 16 03:02:20 2015 - [info] Executed CHANGE MASTER. Mon Nov 16 03:02:20 2015 - [info] Slave started. Mon Nov 16 03:02:20 2015 - [info] End of log messages from 192.168.245.132. Mon Nov 16 03:02:20 2015 - [info] -- Slave recovery on host 192.168.245.132(192.168.245.132:3306) succeeded. Mon Nov 16 03:02:20 2015 - [info] All new slave servers recovered successfully. Mon Nov 16 03:02:20 2015 - [info] Mon Nov 16 03:02:20 2015 - [info] * Phase 5: New master cleanup phase.. Mon Nov 16 03:02:20 2015 - [info] Mon Nov 16 03:02:20 2015 - [info] Resetting slave info on the new master.. Mon Nov 16 03:02:20 2015 - [info] 192.168.245.131: Resetting slave info succeeded. Mon Nov 16 03:02:20 2015 - [info] Master failover to 192.168.245.131(192.168.245.131:3306) completed successfully. Mon Nov 16 03:02:20 2015 - [info] Deleted server1 entry from /etc/masterha/app1.conf . Mon Nov 16 03:02:20 2015 - [info] ----- Failover Report ----- app1: MySQL Master failover 192.168.245.129(192.168.245.129:3306) to 192.168.245.131(192.168.245.131:3306) succeeded Master 192.168.245.129(192.168.245.129:3306) is down! Check MHA Manager logs at node3:/var/log/masterha/app1/app1.log for details. Started automated(non-interactive) failover. The latest slave 192.168.245.131(192.168.245.131:3306) has all relay logs for recovery. Selected 192.168.245.131(192.168.245.131:3306) as a new master. 192.168.245.131(192.168.245.131:3306): OK: Applying all logs succeeded. 192.168.245.132(192.168.245.132:3306): This host has the latest relay log events. Generating relay diff files from the latest slave succeeded. 192.168.245.132(192.168.245.132:3306): OK: Applying all logs succeeded. Slave started, replicating from 192.168.245.131(192.168.245.131:3306) 192.168.245.131(192.168.245.131:3306): Resetting slave info succeeded. Master failover to 192.168.245.131(192.168.245.131:3306) completed successfully.
（2）修复故障master
通常情况下自动切换以后，待原master主机修复后，如果数据完整的情况下，可能想把原来master重新作为新主库的slave，这时我们可以借助当时自动切换时刻的MHA日志来完成对原master的修复。下面是提取相关日志的命令：
[root@node3 masterha]# grep -i "All other slaves should start" /var/log/masterha/app1/app1.log Mon Nov 16 03:02:20 2015 - [info] All other slaves should start replication from here. Statement should be: CHANGE MASTER TO MASTER_HOST='192.168.245.131', MASTER_PORT=3306, MASTER_LOG_FILE='mysql-bin.000013', MASTER_LOG_POS=35416929, MASTER_USER='repl', MASTER_PASSWORD='xxx';
将change master to拿到原master上执行，那么就作为新master的slave了。
（3）在线切换测试
在许多情况下， 需要将现有的主服务器迁移到另外一台服务器上。 比如主服务器硬件故障，RAID 控制卡需要重建，将主服务器移到性能更好的服务器上等等。 MHA 提供快速切换和优雅的阻塞写入，这个切换过程只需要 0.5-2s 的时间，这段时间内数据是无法写入的。在很多情况下，0.5-2s 的阻塞写入是可以接受的。因此切换主服务器不需要计划分配维护时间窗口。
MHA在线切换的大概过程：
1.检测复制设置和确定当前主服务器
2.确定新的主服务器
3.阻塞写入到当前主服务器
4.等待所有从服务器赶上复制
5.授予写入到新的主服务器
6.重新设置从服务器
注意，在线切换的时候应用架构需要考虑以下两个问题：
1.自动识别master和slave的问题（master的机器可能会切换），如果采用了vip的方式，基本可以解决这个问题。
2.负载均衡的问题（可以定义大概的读写比例，每台机器可承担的负载比例，当有机器离开集群时，需要考虑这个问题）
为了保证数据完全一致性，在最快的时间内完成切换，MHA的在线切换必须满足以下条件才会切换成功，否则会切换失败。
1.所有slave的IO线程都在运行
2.所有slave的SQL线程都在运行
3.所有的show slave status的输出中Seconds_Behind_Master参数小于或者等于running_updates_limit秒，如果在切换过程中不指 定running_updates_limit,那么默认情况下running_updates_limit为1秒。
4.在master端，通过show processlist输出，没有一个更新花费的时间大于running_updates_limit秒。
在线切换步骤如下：
首先，停掉MHA监控：
[root@node3 app1]# svc -d /service/masterha_app [root@node3 app1]# checkstatus app1 is stopped(2:NOT_RUNNING).
其次，进行在线切换操作（模拟在线切换主库操作，原主库192.168.245.129变为slave，192.168.245.131提升为新的主库）
[root@node3 masterha]# /usr/bin/masterha_master_switch --conf=/etc/masterha/app1.conf --master_state=alive --new_master_host=192.168.245.131 --new_master_port=3306 --orig_master_is_new_slave --running_updates_limit=10000 Mon Nov 16 21:47:24 2015 - [info] MHA::MasterRotate version 0.56. Mon Nov 16 21:47:24 2015 - [info] Starting online master switch.. Mon Nov 16 21:47:24 2015 - [info] Mon Nov 16 21:47:24 2015 - [info] * Phase 1: Configuration Check Phase.. Mon Nov 16 21:47:24 2015 - [info] Mon Nov 16 21:47:24 2015 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping. Mon Nov 16 21:47:24 2015 - [info] Reading application default configuration from /etc/masterha/app1.conf.. Mon Nov 16 21:47:24 2015 - [info] Reading server configuration from /etc/masterha/app1.conf.. Mon Nov 16 21:47:24 2015 - [info] GTID failover mode = 0 Mon Nov 16 21:47:24 2015 - [info] Current Alive Master: 192.168.245.129(192.168.245.129:3306) Mon Nov 16 21:47:24 2015 - [info] Alive Slaves: Mon Nov 16 21:47:24 2015 - [info] 192.168.245.132(192.168.245.132:3306) Version=5.6.21-log (oldest major version between slaves) log-bin:enabled Mon Nov 16 21:47:24 2015 - [info] Replicating from 192.168.245.129(192.168.245.129:3306) It is better to execute FLUSH NO_WRITE_TO_BINLOG TABLES on the master before switching. Is it ok to execute on 192.168.245.129(192.168.245.129:3306)? (YES/no): yes Mon Nov 16 21:47:35 2015 - [info] Executing FLUSH NO_WRITE_TO_BINLOG TABLES. This may take long time.. Mon Nov 16 21:47:35 2015 - [info] ok. Mon Nov 16 21:47:35 2015 - [info] Checking MHA is not monitoring or doing failover.. Mon Nov 16 21:47:35 2015 - [info] Checking replication health on 192.168.245.132.. Mon Nov 16 21:47:35 2015 - [info] ok. Mon Nov 16 21:47:35 2015 - [error][/usr/share/perl5/vendor_perl/MHA/ServerManager.pm, ln1218] 192.168.245.131 is not alive! Mon Nov 16 21:47:35 2015 - [error][/usr/share/perl5/vendor_perl/MHA/MasterRotate.pm, ln232] Failed to get new master! Mon Nov 16 21:47:35 2015 - [error][/usr/share/perl5/vendor_perl/MHA/ManagerUtil.pm, ln177] Got ERROR: at /usr/bin/masterha_master_switch line 53
这里怎么会报错呢？意思是131这个机器not alive，可是我去检查下没有问题啊，主从也ok的，后来发现了问题所在，原因是：之前启动的manager脚本中加上了--remove_dead_master_conf参数，导致appl.conf中没有131机器的配置。
然后到app1.conf中加上131机器的配置信息，再次执行：
[root@node3 masterha]# /usr/bin/masterha_master_switch --conf=/etc/masterha/app1.conf --master_state=alive --new_master_host=192.168.245.129 --new_master_port=3306 --orig_master_is_new_slave --running_updates_limit=10000 Mon Nov 16 22:34:36 2015 - [info] MHA::MasterRotate version 0.56. Mon Nov 16 22:34:36 2015 - [info] Starting online master switch.. Mon Nov 16 22:34:36 2015 - [info] Mon Nov 16 22:34:36 2015 - [info] * Phase 1: Configuration Check Phase.. Mon Nov 16 22:34:36 2015 - [info] Mon Nov 16 22:34:36 2015 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping. Mon Nov 16 22:34:36 2015 - [info] Reading application default configuration from /etc/masterha/app1.conf.. Mon Nov 16 22:34:36 2015 - [info] Reading server configuration from /etc/masterha/app1.conf.. Mon Nov 16 22:34:37 2015 - [info] GTID failover mode = 0 Mon Nov 16 22:34:37 2015 - [info] Current Alive Master: 192.168.245.131(192.168.245.131:3306) Mon Nov 16 22:34:37 2015 - [info] Alive Slaves: Mon Nov 16 22:34:37 2015 - [info] 192.168.245.129(192.168.245.129:3306) Version=5.6.23-log (oldest major version between slaves) log-bin:enabled Mon Nov 16 22:34:37 2015 - [info] Replicating from 192.168.245.131(192.168.245.131:3306) Mon Nov 16 22:34:37 2015 - [info] Primary candidate for the new Master (candidate_master is set) Mon Nov 16 22:34:37 2015 - [info] 192.168.245.132(192.168.245.132:3306) Version=5.6.21-log (oldest major version between slaves) log-bin:enabled Mon Nov 16 22:34:37 2015 - [info] Replicating from 192.168.245.131(192.168.245.131:3306) It is better to execute FLUSH NO_WRITE_TO_BINLOG TABLES on the master before switching. Is it ok to execute on 192.168.245.131(192.168.245.131:3306)? (YES/no): yes Mon Nov 16 22:34:38 2015 - [info] Executing FLUSH NO_WRITE_TO_BINLOG TABLES. This may take long time.. Mon Nov 16 22:34:38 2015 - [info] ok. Mon Nov 16 22:34:38 2015 - [info] Checking MHA is not monitoring or doing failover.. Mon Nov 16 22:34:38 2015 - [info] Checking replication health on 192.168.245.129.. Mon Nov 16 22:34:38 2015 - [info] ok. Mon Nov 16 22:34:38 2015 - [info] Checking replication health on 192.168.245.132.. Mon Nov 16 22:34:38 2015 - [info] ok. Mon Nov 16 22:34:38 2015 - [info] 192.168.245.129 can be new master. Mon Nov 16 22:34:38 2015 - [info] From: 192.168.245.131(192.168.245.131:3306) (current master) +--192.168.245.129(192.168.245.129:3306) +--192.168.245.132(192.168.245.132:3306) To: 192.168.245.129(192.168.245.129:3306) (new master) +--192.168.245.132(192.168.245.132:3306) +--192.168.245.131(192.168.245.131:3306) Starting master switch from 192.168.245.131(192.168.245.131:3306) to 192.168.245.129(192.168.245.129:3306)? (yes/NO): yes Mon Nov 16 22:34:39 2015 - [info] Checking whether 192.168.245.129(192.168.245.129:3306) is ok for the new master.. Mon Nov 16 22:34:39 2015 - [info] ok. Mon Nov 16 22:34:39 2015 - [info] 192.168.245.131(192.168.245.131:3306): SHOW SLAVE STATUS returned empty result. To check replication filtering rules, temporarily executing CHANGE MASTER to a dummy host. Mon Nov 16 22:34:39 2015 - [info] 192.168.245.131(192.168.245.131:3306): Resetting slave pointing to the dummy host. Mon Nov 16 22:34:39 2015 - [info] ** Phase 1: Configuration Check Phase completed. Mon Nov 16 22:34:39 2015 - [info] Mon Nov 16 22:34:39 2015 - [info] * Phase 2: Rejecting updates Phase.. Mon Nov 16 22:34:39 2015 - [info] Mon Nov 16 22:34:39 2015 - [info] Executing master ip online change script to disable write on the current master: Mon Nov 16 22:34:39 2015 - [info] /etc/masterha/master_ip_online_change --command=stop --orig_master_host=192.168.245.131 --orig_master_ip=192.168.245.131 --orig_master_port=3306 --orig_master_user='root' --orig_master_password='root' --new_master_host=192.168.245.129 --new_master_ip=192.168.245.129 --new_master_port=3306 --new_master_user='root' --new_master_password='root' --orig_master_ssh_user=root --new_master_ssh_user=root --orig_master_is_new_slave Unknown option: orig_master_password Unknown option: new_master_password Unknown option: orig_master_ssh_user Unknown option: new_master_ssh_user Unknown option: orig_master_is_new_slave Mon Nov 16 22:34:39 2015 501641 Set read_only on the new master.. ok. Mon Nov 16 22:34:39 2015 508208 Set read_only=1 on the orig master.. ok. Disabling the VIP on old master: 192.168.245.131 Mon Nov 16 22:34:39 2015 876127 Killing all application threads.. Mon Nov 16 22:34:39 2015 876272 done. Mon Nov 16 22:34:39 2015 - [info] ok. Mon Nov 16 22:34:39 2015 - [info] Locking all tables on the orig master to reject updates from everybody (including root): Mon Nov 16 22:34:39 2015 - [info] Executing FLUSH TABLES WITH READ LOCK.. Mon Nov 16 22:34:39 2015 - [info] ok. Mon Nov 16 22:34:39 2015 - [info] Orig master binlog:pos is mysql-bin.000014:120. Mon Nov 16 22:34:39 2015 - [info] Waiting to execute all relay logs on 192.168.245.129(192.168.245.129:3306).. Mon Nov 16 22:34:39 2015 - [info] master_pos_wait(mysql-bin.000014:120) completed on 192.168.245.129(192.168.245.129:3306). Executed 0 events. Mon Nov 16 22:34:39 2015 - [info] done. Mon Nov 16 22:34:39 2015 - [info] Getting new master's binlog name and position.. Mon Nov 16 22:34:39 2015 - [info] mysql-bin.000024:120 Mon Nov 16 22:34:39 2015 - [info] All other slaves should start replication from here. Statement should be: CHANGE MASTER TO MASTER_HOST='192.168.245.129', MASTER_PORT=3306, MASTER_LOG_FILE='mysql-bin.000024', MASTER_LOG_POS=120, MASTER_USER='repl', MASTER_PASSWORD='xxx'; Mon Nov 16 22:34:39 2015 - [info] Executing master ip online change script to allow write on the new master: Mon Nov 16 22:34:39 2015 - [info] /etc/masterha/master_ip_online_change --command=start --orig_master_host=192.168.245.131 --orig_master_ip=192.168.245.131 --orig_master_port=3306 --orig_master_user='root' --orig_master_password='root' --new_master_host=192.168.245.129 --new_master_ip=192.168.245.129 --new_master_port=3306 --new_master_user='root' --new_master_password='root' --orig_master_ssh_user=root --new_master_ssh_user=root --orig_master_is_new_slave Unknown option: orig_master_password Unknown option: new_master_password Unknown option: orig_master_ssh_user Unknown option: new_master_ssh_user Unknown option: orig_master_is_new_slave Mon Nov 16 22:34:40 2015 165977 Set read_only=0 on the new master. Enabling the VIP - 192.168.245.100/32 on the new master - 192.168.245.129 Mon Nov 16 22:34:40 2015 - [info] ok. Mon Nov 16 22:34:40 2015 - [info] Mon Nov 16 22:34:40 2015 - [info] * Switching slaves in parallel.. Mon Nov 16 22:34:40 2015 - [info] Mon Nov 16 22:34:40 2015 - [info] -- Slave switch on host 192.168.245.132(192.168.245.132:3306) started, pid: 29022 Mon Nov 16 22:34:40 2015 - [info] Mon Nov 16 22:34:40 2015 - [info] Log messages from 192.168.245.132 ... Mon Nov 16 22:34:40 2015 - [info] Mon Nov 16 22:34:40 2015 - [info] Waiting to execute all relay logs on 192.168.245.132(192.168.245.132:3306).. Mon Nov 16 22:34:40 2015 - [info] master_pos_wait(mysql-bin.000014:120) completed on 192.168.245.132(192.168.245.132:3306). Executed 0 events. Mon Nov 16 22:34:40 2015 - [info] done. Mon Nov 16 22:34:40 2015 - [info] Resetting slave 192.168.245.132(192.168.245.132:3306) and starting replication from the new master 192.168.245.129(192.168.245.129:3306).. Mon Nov 16 22:34:40 2015 - [info] Executed CHANGE MASTER. Mon Nov 16 22:34:40 2015 - [info] Slave started. Mon Nov 16 22:34:40 2015 - [info] End of log messages from 192.168.245.132 ... Mon Nov 16 22:34:40 2015 - [info] Mon Nov 16 22:34:40 2015 - [info] -- Slave switch on host 192.168.245.132(192.168.245.132:3306) succeeded. Mon Nov 16 22:34:40 2015 - [info] Unlocking all tables on the orig master: Mon Nov 16 22:34:40 2015 - [info] Executing UNLOCK TABLES.. Mon Nov 16 22:34:40 2015 - [info] ok. Mon Nov 16 22:34:40 2015 - [info] Starting orig master as a new slave.. Mon Nov 16 22:34:40 2015 - [info] Resetting slave 192.168.245.131(192.168.245.131:3306) and starting replication from the new master 192.168.245.129(192.168.245.129:3306).. Mon Nov 16 22:34:40 2015 - [info] Executed CHANGE MASTER. Mon Nov 16 22:34:41 2015 - [info] Slave started. Mon Nov 16 22:34:41 2015 - [info] All new slave servers switched successfully. Mon Nov 16 22:34:41 2015 - [info] Mon Nov 16 22:34:41 2015 - [info] * Phase 5: New master cleanup phase.. Mon Nov 16 22:34:41 2015 - [info] Mon Nov 16 22:34:41 2015 - [info] 192.168.245.129: Resetting slave info succeeded. Mon Nov 16 22:34:41 2015 - [info] Switching master to 192.168.245.129(192.168.245.129:3306) completed successfully.
其中参数的意思：
--orig_master_is_new_slave 切换时加上此参数是将原 master 变为 slave 节点，如果不加此参数，原来的 master 将不启动
--running_updates_limit=10000,故障切换时,候选master 如果有延迟的话， mha 切换不能成功，加上此参数表示延迟在此时间范围内都可切换（单位为s），但是切换的时间长短是由recover 时relay 日志的大小决定
（4）切换时发送邮件：
需要创建一个send_mail脚本，然后将脚本路径写入app1.conf中即可。
#!/usr/bin/perl # Copyright (C) 2011 DeNA Co.,Ltd. # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program; if not, write to the Free Software # Foundation, Inc., # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA ## Note: This is a sample script and is not complete. Modify the script based on your environment. use strict; use warnings FATAL => 'all'; use Mail::Sender; use Getopt::Long; #new_master_host and new_slave_hosts are set only when recovering master succeeded my ( $dead_master_host, $new_master_host, $new_slave_hosts, $subject, $body ); my $smtp='smtp.163.com'; my $mail_from='xxxx'; my $mail_user='xxxxx'; my $mail_pass='xxxxx'; my $mail_to=['xxxx','xxxx']; GetOptions( 'orig_master_host=s' => $dead_master_host, 'new_master_host=s' => $new_master_host, 'new_slave_hosts=s' => $new_slave_hosts, 'subject=s' => $subject, 'body=s' => $body, ); mailToContacts($smtp,$mail_from,$mail_user,$mail_pass,$mail_to,$subject,$body); sub mailToContacts { my ( $smtp, $mail_from, $user, $passwd, $mail_to, $subject, $msg ) = @_; open my $DEBUG, "> /tmp/monitormail.log" or die "Can't open the debug file:$! "; my $sender = new Mail::Sender { ctype => 'text/plain; charset=utf-8', encoding => 'utf-8', smtp => $smtp, from => $mail_from, auth => 'LOGIN', TLS_allowed => '0', authid => $user, authpwd => $passwd, to => $mail_to, subject => $subject, debug => $DEBUG }; $sender->MailMsg( { msg => $msg, debug => $DEBUG } ) or print $Mail::Sender::Error; return 1; } # Do whatever you want here exit 0;
至此，mysql mha部分就搞定了，下面将会结合mha这个架构加入代理层，从而实现读写分离功能，主要采用360公司的Atlas，敬请期待。。。