基于GTID的主从replication并配合MHA搭建高可用架构，请参考之前的博客：http://linzhijian.blog.51cto.com/1047212/1906434。这里只叙述如何在此基础上增加maxscale中间件，实现读写分离的功能。
MaxScale是maridb开发的一个MySQL数据中间件，其配置简单，能够实现读写分离，并且可以根据主从状态实现写库的自动切换。官方文档：https://mariadb.com/kb/en/mariadb-enterprise/about-mariadb-maxscale/
测试环境简要介绍：
master:192.168.110.131:3306
slave1: 192.168.110.132:3306
slave2: 192.168.110.130:3306
maxscale: 192.168.110.132
maxscale安装：
1、依赖包安装：
yum install libaio.x86_64 libaio-devel.x86_64 novacom-server.x86_64 libedit -y2、maxscale包下载：
https://downloads.mariadb.com/files/MaxScale
maxscale-2.0.5-1.centos.6.x86_64.rpm3、创建监控用户：
mysql> create user scalemon@'%' identified by "scalemon";
mysql> grant replication slave, replication client on *.* to scalemon@'%'; 4、创建路由用户：
mysql> create user scaleroute@'%' identified by "scaleroute";
mysql> grant select on mysql.* to scaleroute@'%';
mysql> grant show databases on *.* to 'scaleroute'@'%';5、修改配置文件：
vim /etc/maxscale.conf
# MaxScale documentation on GitHub:
# https://github.com/mariadb-corporation/MaxScale/blob/master/Documentation/Documentation-Contents.md
# Global parameters
#
# Complete list of configuration options:
# https://github.com/mariadb-corporation/MaxScale/blob/master/Documentation/Getting-Started/Configuration-Guide.md
[maxscale]
threads=1
log_info=1
logdir=/tmp/
# Server definitions
#
# Set the address of the server to the network
# address of a MySQL server.
#
[server1]
type=server
address=192.168.110.131
port=3306
protocol=MySQLBackend
[server2]
type=server
address=192.168.110.132
port=3306
protocol=MySQLBackend
[server3]
type=server
address=192.168.110.130
port=3306
protocol=MySQLBackend
# Monitor for the servers
#
# This will keep MaxScale aware of the state of the servers.
# MySQL Monitor documentation:
# https://github.com/mariadb-corporation/MaxScale/blob/master/Documentation/Monitors/MySQL-Monitor.md
[MySQL Monitor]
type=monitor
module=mysqlmon
servers=server1,server2,server3
user=scalemon
passwd=scalemon
monitor_interval=10000
# Service definitions
#
# Service Definition for a read-only service and
# a read/write splitting service.
#
# ReadConnRoute documentation:
# https://github.com/mariadb-corporation/MaxScale/blob/master/Documentation/Routers/ReadConnRoute.md
#[Read-Only Service]
#type=service
#router=readconnroute
#servers=server2,server3
#user=scaleroute
#passwd=scaleroute
#router_options=slave
# ReadWriteSplit documentation:
# https://github.com/mariadb-corporation/MaxScale/blob/master/Documentation/Routers/ReadWriteSplit.md
[Read-Write Service]
type=service
router=readwritesplit
servers=server1,server2,server3
user=scaleroute
passwd=scaleroute
max_slave_connections=100%
# This service enables the use of the MaxAdmin interface
# MaxScale administration guide:
# https://github.com/mariadb-corporation/MaxScale/blob/master/Documentation/Reference/MaxAdmin.md
[MaxAdmin Service]
type=service
router=cli
# Listener definitions for the services
#
# These listeners represent the ports the
# services will listen on.
#
#[Read-Only Listener]
#type=listener
#service=Read-Only Service
#protocol=MySQLClient
#port=4008
[Read-Write Listener]
type=listener
service=Read-Write Service
protocol=MySQLClient
port=4006
[MaxAdmin Listener]
type=listener
service=MaxAdmin Service
protocol=maxscaled
socket=default6、启动服务：
service maxscale start 或者 maxscale --conf=/etc/maxscale.conf 7、检查maxscale日志：
cat /tmp/maxscale1.log
MariaDB Corporation MaxScale /tmp/maxscale1.log Fri Apr 7 12:26:23 2017
-----------------------------------------------------------------------
2017-04-07 12:26:23 notice : Working directory: /tmp
2017-04-07 12:26:23 notice : MariaDB MaxScale 2.0.5 started
2017-04-07 12:26:23 notice : MaxScale is running in process 10866
2017-04-07 12:26:23 notice : Configuration file: /etc/maxscale.cnf
2017-04-07 12:26:23 notice : Log directory: /tmp
2017-04-07 12:26:23 notice : Data directory: /var/lib/maxscale
2017-04-07 12:26:23 notice : Module directory: /usr/lib64/maxscale
2017-04-07 12:26:23 notice : Service cache: /var/cache/maxscale
2017-04-07 12:26:23 notice : The logging of informational messages has been enabled.
2017-04-07 12:26:23 notice : Initialise CLI router module V1.0.0.
2017-04-07 12:26:23 notice : Loaded module cli: V1.0.0 from /usr/lib64/maxscale/libcli.so
2017-04-07 12:26:23 notice : Initializing statemend-based read/write split router module.
2017-04-07 12:26:23 notice : Loaded module readwritesplit: V1.1.0 from /usr/lib64/maxscale/libreadwritesplit.so
2017-04-07 12:26:23 notice : Initialise the MySQL Monitor module V1.4.0.
2017-04-07 12:26:23 notice : Loaded module mysqlmon: V1.4.0 from /usr/lib64/maxscale/libmysqlmon.so
2017-04-07 12:26:23 notice : No query classifier specified, using default 'qc_sqlite'.
2017-04-07 12:26:23 notice : Loaded module qc_sqlite: V1.0.0 from /usr/lib64/maxscale/libqc_sqlite.so
2017-04-07 12:26:23 info : qc_sqlite loaded.
2017-04-07 12:26:23 info : qc_sqlite: In-memory sqlite database successfully opened for thread 140338182019040.
2017-04-07 12:26:23 notice : Encrypted password file /var/lib/maxscale/.secrets can't be accessed (No such file or directory). Password encryption is not used.
2017-04-07 12:26:23 info : Notification service feedback is not enabled.
2017-04-07 12:26:23 info : Read-Write Service: User scaleroute@% for database mysql added to service user table.
2017-04-07 12:26:23 info : Read-Write Service: User repl@192.168.% for database no db added to service user table.
2017-04-07 12:26:23 info : Read-Write Service: User linzj@192.168.110.% for database ANY added to service user table.
2017-04-07 12:26:23 info : Read-Write Service: User mha@192.168.110.% for database ANY added to service user table.
2017-04-07 12:26:23 info : Read-Write Service: User plum@192.168.110.% for database ANY added to service user table.
2017-04-07 12:26:23 info : Read-Write Service: User plum@192.168.110.131 for database no db added to service user table.
2017-04-07 12:26:23 info : Read-Write Service: User test@127.0.0.1 for database ANY added to service user table.
2017-04-07 12:26:23 info : Read-Write Service: User scalemon@% for database no db added to service user table.
2017-04-07 12:26:23 notice : Loaded 8 MySQL Users for service [Read-Write Service].
2017-04-07 12:26:23 notice : Loaded module MySQLClient: V1.1.0 from /usr/lib64/maxscale/libMySQLClient.so
2017-04-07 12:26:23 notice : Listening connections at 0.0.0.0:4006 with protocol MySQL
2017-04-07 12:26:23 info : Started session [0] for Read-Write Service service
2017-04-07 12:26:23 info : Initialise MaxScaled Protocol module.
2017-04-07 12:26:23 notice : Loaded module maxscaled: V2.0.0 from /usr/lib64/maxscale/libmaxscaled.so
2017-04-07 12:26:23 notice : Listening connections at /tmp/maxadmin.sock with protocol MaxScale Admin
2017-04-07 12:26:23 info : Started session [0] for MaxAdmin Service service
2017-04-07 12:26:23 notice : MaxScale started with 1 server threads.
2017-04-07 12:26:23 notice : Started MaxScale log flusher.
2017-04-07 12:26:23 notice : Server changed state: server1[192.168.110.131:3306]: new_master. [Running] -> [Master, Running]
2017-04-07 12:26:23 notice : Server changed state: server2[192.168.110.132:3306]: new_slave. [Running] -> [Slave, Running]
2017-04-07 12:26:23 notice : Server changed state: server3[192.168.110.130:3306]: new_slave. [Running] -> [Slave, Running]
2017-04-07 12:26:23 notice : A Master Server is now available: 192.168.110.131:33068、登陆maxscale管理器，检查后端数据库状态信息：
maxadmin -S /tmp/maxadmin.sock
MaxScale> list servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server | Address | Port | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
server1 | 192.168.110.131 | 3306 | 0 | Master, Running
server2 | 192.168.110.132 | 3306 | 0 | Slave, Running
server3 | 192.168.110.130 | 3306 | 0 | Slave, Running
-------------------+-----------------+-------+-------------+--------------------
MaxScale> list services
Services.
--------------------------+----------------------+--------+---------------
Service Name | Router Module | #Users | Total Sessions
--------------------------+----------------------+--------+---------------
Read-Write Service | readwritesplit | 1 | 1
MaxAdmin Service | cli | 2 | 2
--------------------------+----------------------+--------+---------------
MaxScale>9、验证maxscale的monitor插件：
关闭mysql2的数据库服务：sh /home/linzj/shell/mysql.sh stop
MaxScale> list servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server | Address | Port | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
server1 | 192.168.110.131 | 3306 | 0 | Master, Running
server2 | 192.168.110.132 | 3306 | 0 | Slave, Running
server3 | 192.168.110.130 | 3306 | 0 | Slave, Running
-------------------+-----------------+-------+-------------+--------------------
MaxScale> list servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server | Address | Port | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
server1 | 192.168.110.131 | 3306 | 0 | Master, Running
server2 | 192.168.110.132 | 3306 | 0 | Down
server3 | 192.168.110.130 | 3306 | 0 | Slave, Running
-------------------+-----------------+-------+-------------+--------------------重新拉起mysql2的数据库服务： sh /home/linzh/shell/mysql.sh start
MaxScale> list servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server | Address | Port | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
server1 | 192.168.110.131 | 3306 | 0 | Master, Running
server2 | 192.168.110.132 | 3306 | 0 | Down
server3 | 192.168.110.130 | 3306 | 0 | Slave, Running
-------------------+-----------------+-------+-------------+--------------------
MaxScale> list servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server | Address | Port | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
server1 | 192.168.110.131 | 3306 | 0 | Master, Running
server2 | 192.168.110.132 | 3306 | 0 | Running
server3 | 192.168.110.130 | 3306 | 0 | Slave, Running
-------------------+-----------------+-------+-------------+--------------------由于配置了skip_slave_start = 1这个参数，mysql2重启后需要手工start slave启动复制线程。
mysql> start slave;
MaxScale> list servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server | Address | Port | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
server1 | 192.168.110.131 | 3306 | 0 | Master, Running
server2 | 192.168.110.132 | 3306 | 0 | Running
server3 | 192.168.110.130 | 3306 | 0 | Slave, Running
-------------------+-----------------+-------+-------------+--------------------
MaxScale> list servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server | Address | Port | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
server1 | 192.168.110.131 | 3306 | 0 | Master, Running
server2 | 192.168.110.132 | 3306 | 0 | Slave, Running
server3 | 192.168.110.130 | 3306 | 0 | Slave, Running
-------------------+-----------------+-------+-------------+--------------------10、验证读写分离：
[root@ansible log]# mysql -ulinzj -plinzj -P4006 -h 192.168.110.130
Warning: Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 11069
Server version: 5.5.5-10.0.0 2.0.5-maxscale Source distribution
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
linzj@192.168.110.130:4006 12:54: [(none)]>
linzj@192.168.110.130:4006 12:54: [(none)]>
linzj@192.168.110.130:4006 12:54: [(none)]>
linzj@192.168.110.130:4006 12:54: [(none)]>select @@hostname;
+------------+
| @@hostname |
+------------+
| mysql2 |
+------------+
1 row in set (0.00 sec)
linzj@192.168.110.130:4006 12:54: [(none)]>begin;
Query OK, 0 rows affected (0.00 sec)
linzj@192.168.110.130:4006 12:54: [(none)]>select @@hostname;
+------------+
| @@hostname |
+------------+
| mysql1 |
+------------+
1 row in set (0.00 sec)
linzj@192.168.110.130:4006 12:54: [(none)]>rollback;
Query OK, 0 rows affected (0.00 sec)
linzj@192.168.110.130:4006 12:54: [(none)]>select @@hostname;
+------------+
| @@hostname |
+------------+
| mysql2 |
+------------+
1 row in set (0.00 sec)
linzj@192.168.110.130:4006 12:54: [(none)]>select @@hostname;
+------------+
| @@hostname |
+------------+
| mysql2 |
+------------+
1 row in set (0.00 sec)从select的结果可知：读操作都路由到mysql2（slave）上去执行，而写操作路由到mysql1（master）上去执行，读写分离功能实现。
11、MHA高可用情形一（master crash）
环境：启动MHA manager进程， 手工pkill mysql1的数据库服务
MaxScale> list servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server | Address | Port | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
server1 | 192.168.110.131 | 3306 | 0 | Master, Running
server2 | 192.168.110.132 | 3306 | 0 | Slave, Running
server3 | 192.168.110.130 | 3306 | 0 | Slave, Running
-------------------+-----------------+-------+-------------+--------------------
MaxScale> list servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server | Address | Port | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
server1 | 192.168.110.131 | 3306 | 0 | Down
server2 | 192.168.110.132 | 3306 | 0 | Master, Running
server3 | 192.168.110.130 | 3306 | 0 | Slave, Running
-------------------+-----------------+-------+-------------+-------------------[root@ansible shell]# tail /var/log/masterha/app1/manager.log
Check MHA Manager logs at ansible:/var/log/masterha/app1/manager.log for details.
Started automated(non-interactive) failover.
Invalidated master IP address on mysql1(192.168.110.131:3306)
Selected mysql2(192.168.110.132:3306) as a new master.
mysql2(192.168.110.132:3306): OK: Applying all logs succeeded.
mysql2(192.168.110.132:3306): OK: Activated master IP address.
ansible(192.168.110.130:3306): OK: Slave started, replicating from mysql2(192.168.110.132:3306)
mysql2(192.168.110.132:3306): Resetting slave info succeeded.
Master failover to mysql2(192.168.110.132:3306) completed successfully.从MHA的failover日志可知，mysql1主库down,mysql2升级成新的master主库。从maxscale管理界面上也可以看到，maxscale也能正确地识别了后端数据库的状态。
12、MHA高可用情形二（online change）
环境：继续上面的例子，目前mysql2为主库，mysql1重启后根据MHA的failover日志的信息重新配置change master作为从库加入集群。
MaxScale> list servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server | Address | Port | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
server1 | 192.168.110.131 | 3306 | 0 | Running
server2 | 192.168.110.132 | 3306 | 0 | Master, Running
server3 | 192.168.110.130 | 3306 | 0 | Slave, Running
-------------------+-----------------+-------+-------------+--------------------
MaxScale> list servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server | Address | Port | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
server1 | 192.168.110.131 | 3306 | 0 | Slave, Running
server2 | 192.168.110.132 | 3306 | 0 | Master, Running
server3 | 192.168.110.130 | 3306 | 0 | Slave, Running
-------------------+-----------------+-------+-------------+--------------------采用MHA online change的方式，将mysql1重新升级成主库。
shell>sh /home/linzj/shell/masterha_switch.sh manual_online_change
MHA Manager is not running on app1(2:NOT_RUNNING).
Fri Apr 7 18:00:21 2017 - [info] MHA::MasterRotate version 0.56.
Fri Apr 7 18:00:21 2017 - [info] Starting online master switch..
Fri Apr 7 18:00:21 2017 - [info]
Fri Apr 7 18:00:21 2017 - [info] * Phase 1: Configuration Check Phase..
Fri Apr 7 18:00:21 2017 - [info]
Fri Apr 7 18:00:21 2017 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Fri Apr 7 18:00:21 2017 - [info] Reading application default configuration from /etc/masterha/app1.cnf..
Fri Apr 7 18:00:21 2017 - [info] Reading server configuration from /etc/masterha/app1.cnf..
Fri Apr 7 18:00:21 2017 - [info] GTID failover mode = 1
Fri Apr 7 18:00:21 2017 - [info] Current Alive Master: mysql2(192.168.110.132:3306)
Fri Apr 7 18:00:21 2017 - [info] Alive Slaves:
Fri Apr 7 18:00:21 2017 - [info] mysql1(192.168.110.131:3306) Version=5.6.34-log (oldest major version between slaves) log-bin:enabled
Fri Apr 7 18:00:21 2017 - [info] GTID ON
Fri Apr 7 18:00:21 2017 - [info] Replicating from 192.168.110.132(192.168.110.132:3306)
Fri Apr 7 18:00:21 2017 - [info] ansible(192.168.110.130:3306) Version=5.6.34-log (oldest major version between slaves) log-bin:enabled
Fri Apr 7 18:00:21 2017 - [info] GTID ON
Fri Apr 7 18:00:21 2017 - [info] Replicating from 192.168.110.132(192.168.110.132:3306)
Fri Apr 7 18:00:21 2017 - [info] Not candidate for the new Master (no_master is set)
Fri Apr 7 18:00:21 2017 - [info] Executing FLUSH NO_WRITE_TO_BINLOG TABLES. This may take long time..
Fri Apr 7 18:00:21 2017 - [info] ok.
Fri Apr 7 18:00:21 2017 - [info] Checking MHA is not monitoring or doing failover..
Fri Apr 7 18:00:21 2017 - [info] Checking replication health on mysql1..
Fri Apr 7 18:00:21 2017 - [info] ok.
Fri Apr 7 18:00:21 2017 - [info] Checking replication health on ansible..
Fri Apr 7 18:00:21 2017 - [info] ok.
Fri Apr 7 18:00:21 2017 - [info] mysql1 can be new master.
Fri Apr 7 18:00:21 2017 - [info]
From:
mysql2(192.168.110.132:3306) (current master)
+--mysql1(192.168.110.131:3306)
+--ansible(192.168.110.130:3306)
To:
mysql1(192.168.110.131:3306) (new master)
+--ansible(192.168.110.130:3306)
+--mysql2(192.168.110.132:3306)
Fri Apr 7 18:00:21 2017 - [info] Checking whether mysql1(192.168.110.131:3306) is ok for the new master..
Fri Apr 7 18:00:21 2017 - [info] ok.
Fri Apr 7 18:00:21 2017 - [info] mysql2(192.168.110.132:3306): SHOW SLAVE STATUS returned empty result. To check replication filtering rules, temporarily executing CHANGE MASTER to a dummy host.
Fri Apr 7 18:00:21 2017 - [info] mysql2(192.168.110.132:3306): Resetting slave pointing to the dummy host.
Fri Apr 7 18:00:21 2017 - [info] ** Phase 1: Configuration Check Phase completed.
Fri Apr 7 18:00:21 2017 - [info]
Fri Apr 7 18:00:21 2017 - [info] * Phase 2: Rejecting updates Phase..
Fri Apr 7 18:00:21 2017 - [info]
Fri Apr 7 18:00:21 2017 - [info] Executing master ip online change script to disable write on the current master:
Fri Apr 7 18:00:21 2017 - [info] /usr/bin/master_ip_online_change --command=stop --orig_master_host=mysql2 --orig_master_ip=192.168.110.132 --orig_master_port=3306 --orig_master_user='mha' --orig_master_password='mha' --new_master_host=mysql1 --new_master_ip=192.168.110.131 --new_master_port=3306 --new_master_user='mha' --new_master_password='mha' --orig_master_ssh_user=root --new_master_ssh_user=root --orig_master_is_new_slave
Fri Apr 7 18:00:21 2017 637019 Set read_only on the new master.. ok.
Fri Apr 7 18:00:21 2017 639365 Waiting all running 2 threads are disconnected.. (max 1500 milliseconds)
{'Time' => '281','Command' => 'Binlog Dump GTID','db' => undef,'Id' => '55','Info' => undef,'User' => 'repl','State' => 'Master has sent all binlog to slave; waiting for binlog to be updated','Host' => '192.168.110.130:33058'}
{'Time' => '73','Command' => 'Binlog Dump GTID','db' => undef,'Id' => '56','Info' => undef,'User' => 'repl','State' => 'Master has sent all binlog to slave; waiting for binlog to be updated','Host' => '192.168.110.131:50008'}
Fri Apr 7 18:00:22 2017 144206 Waiting all running 2 threads are disconnected.. (max 1000 milliseconds)
{'Time' => '281','Command' => 'Binlog Dump GTID','db' => undef,'Id' => '55','Info' => undef,'User' => 'repl','State' => 'Master has sent all binlog to slave; waiting for binlog to be updated','Host' => '192.168.110.130:33058'}
{'Time' => '73','Command' => 'Binlog Dump GTID','db' => undef,'Id' => '56','Info' => undef,'User' => 'repl','State' => 'Master has sent all binlog to slave; waiting for binlog to be updated','Host' => '192.168.110.131:50008'}
Fri Apr 7 18:00:22 2017 649414 Waiting all running 2 threads are disconnected.. (max 500 milliseconds)
{'Time' => '282','Command' => 'Binlog Dump GTID','db' => undef,'Id' => '55','Info' => undef,'User' => 'repl','State' => 'Master has sent all binlog to slave; waiting for binlog to be updated','Host' => '192.168.110.130:33058'}
{'Time' => '74','Command' => 'Binlog Dump GTID','db' => undef,'Id' => '56','Info' => undef,'User' => 'repl','State' => 'Master has sent all binlog to slave; waiting for binlog to be updated','Host' => '192.168.110.131:50008'}
Fri Apr 7 18:00:23 2017 153220 Set read_only=1 on the orig master.. ok.
Fri Apr 7 18:00:23 2017 154715 Waiting all running 2 queries are disconnected.. (max 500 milliseconds)
{'Time' => '282','Command' => 'Binlog Dump GTID','db' => undef,'Id' => '55','Info' => undef,'User' => 'repl','State' => 'Master has sent all binlog to slave; waiting for binlog to be updated','Host' => '192.168.110.130:33058'}
{'Time' => '74','Command' => 'Binlog Dump GTID','db' => undef,'Id' => '56','Info' => undef,'User' => 'repl','State' => 'Master has sent all binlog to slave; waiting for binlog to be updated','Host' => '192.168.110.131:50008'}
Fri Apr 7 18:00:23 2017 658225 Killing all application threads..
Fri Apr 7 18:00:23 2017 659547 done.
Disabling the VIP on old master: mysql2
Fri Apr 7 18:00:24 2017 - [info] ok.
Fri Apr 7 18:00:24 2017 - [info] Locking all tables on the orig master to reject updates from everybody (including root):
Fri Apr 7 18:00:24 2017 - [info] Executing FLUSH TABLES WITH READ LOCK..
Fri Apr 7 18:00:24 2017 - [info] ok.
Fri Apr 7 18:00:24 2017 - [info] Orig master binlog:pos is mysql-bin.000003:188723758.
Fri Apr 7 18:00:24 2017 - [info] Waiting to execute all relay logs on mysql1(192.168.110.131:3306)..
Fri Apr 7 18:00:24 2017 - [info] master_pos_wait(mysql-bin.000003:188723758) completed on mysql1(192.168.110.131:3306). Executed 0 events.
Fri Apr 7 18:00:24 2017 - [info] done.
Fri Apr 7 18:00:24 2017 - [info] Getting new master's binlog name and position..
Fri Apr 7 18:00:24 2017 - [info] mysql-bin.000007:191
Fri Apr 7 18:00:24 2017 - [info] All other slaves should start replication from here. Statement should be: CHANGE MASTER TO MASTER_HOST='mysql1 or 192.168.110.131', MASTER_PORT=3306, MASTER_AUTO_POSITION=1, MASTER_USER='repl', MASTER_PASSWORD='xxx';
Fri Apr 7 18:00:24 2017 - [info] Executing master ip online change script to allow write on the new master:
Fri Apr 7 18:00:24 2017 - [info] /usr/bin/master_ip_online_change --command=start --orig_master_host=mysql2 --orig_master_ip=192.168.110.132 --orig_master_port=3306 --orig_master_user='mha' --orig_master_password='mha' --new_master_host=mysql1 --new_master_ip=192.168.110.131 --new_master_port=3306 --new_master_user='mha' --new_master_password='mha' --orig_master_ssh_user=root --new_master_ssh_user=root --orig_master_is_new_slave
Fri Apr 7 18:00:24 2017 190044 Set read_only=0 on the new master.
Enabling the VIP - 192.168.110.100 on the new master - mysql1
Fri Apr 7 18:00:27 2017 - [info] ok.
Fri Apr 7 18:00:27 2017 - [info]
Fri Apr 7 18:00:27 2017 - [info] * Switching slaves in parallel..
Fri Apr 7 18:00:27 2017 - [info]
Fri Apr 7 18:00:27 2017 - [info] -- Slave switch on host ansible(192.168.110.130:3306) started, pid: 11714
Fri Apr 7 18:00:27 2017 - [info]
Fri Apr 7 18:00:28 2017 - [info] Log messages from ansible ...
Fri Apr 7 18:00:28 2017 - [info]
Fri Apr 7 18:00:27 2017 - [info] Waiting to execute all relay logs on ansible(192.168.110.130:3306)..
Fri Apr 7 18:00:27 2017 - [info] master_pos_wait(mysql-bin.000003:188723758) completed on ansible(192.168.110.130:3306). Executed 0 events.
Fri Apr 7 18:00:27 2017 - [info] done.
Fri Apr 7 18:00:27 2017 - [info] Resetting slave ansible(192.168.110.130:3306) and starting replication from the new master mysql1(192.168.110.131:3306)..
Fri Apr 7 18:00:27 2017 - [info] Executed CHANGE MASTER.
Fri Apr 7 18:00:28 2017 - [info] Slave started.
Fri Apr 7 18:00:28 2017 - [info] End of log messages from ansible ...
Fri Apr 7 18:00:28 2017 - [info]
Fri Apr 7 18:00:28 2017 - [info] -- Slave switch on host ansible(192.168.110.130:3306) succeeded.
Fri Apr 7 18:00:28 2017 - [info] Unlocking all tables on the orig master:
Fri Apr 7 18:00:28 2017 - [info] Executing UNLOCK TABLES..
Fri Apr 7 18:00:28 2017 - [info] ok.
Fri Apr 7 18:00:28 2017 - [info] Starting orig master as a new slave..
Fri Apr 7 18:00:28 2017 - [info] Resetting slave mysql2(192.168.110.132:3306) and starting replication from the new master mysql1(192.168.110.131:3306)..
Fri Apr 7 18:00:28 2017 - [info] Executed CHANGE MASTER.
Fri Apr 7 18:00:29 2017 - [info] Slave started.
Fri Apr 7 18:00:29 2017 - [info] All new slave servers switched successfully.
Fri Apr 7 18:00:29 2017 - [info]
Fri Apr 7 18:00:29 2017 - [info] * Phase 5: New master cleanup phase..
Fri Apr 7 18:00:29 2017 - [info]
Fri Apr 7 18:00:29 2017 - [info] mysql1: Resetting slave info succeeded.
Fri Apr 7 18:00:29 2017 - [info] Switching master to mysql1(192.168.110.131:3306) completed successfully.MaxScale> list servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server | Address | Port | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
server1 | 192.168.110.131 | 3306 | 0 | Slave, Running
server2 | 192.168.110.132 | 3306 | 0 | Master, Running
server3 | 192.168.110.130 | 3306 | 0 | Slave, Running
-------------------+-----------------+-------+-------------+--------------------
MaxScale> list servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server | Address | Port | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
server1 | 192.168.110.131 | 3306 | 0 | Master, Running
server2 | 192.168.110.132 | 3306 | 0 | Slave, Running
server3 | 192.168.110.130 | 3306 | 0 | Slave, Running
-------------------+-----------------+-------+-------------+--------------------从MHA的online change日志中可以发现，mysql1重新升级成主库，mysql2降级为从库。而maxscale也可以准确的识别出后端数据库的状态。
13、通过sysbench压测maxscale性能。
压测脚本test_sysbench.sh如下：
#!/bin/sh
ssh root@ansible '/usr/bin/ansible all -m shell -a "sh /home/linzj/shell/mysql.sh stop; sh /home/linzj/shell/mysql.sh start"'
sleep 60
sysbench --test=oltp --mysql-host=192.168.110.130 --mysql-port=4006 --mysql-user=linzj --mysql-password=linzj --mysql-db=sbtest1 --oltp-num-tables=10 --oltp-table-size=500000 --report-interval=100 --max-requests=0 --oltp-test-mode=complex --oltp-nontrx-mode=select --oltp-read-only=on --max-time=300 --num-threads=16 run > /tmp/130_4006_readonly.log
ssh root@ansible '/usr/bin/ansible all -m shell -a "sh /home/linzj/shell/mysql.sh stop; sh /home/linzj/shell/mysql.sh start"'
sleep 60
sysbench --test=oltp --mysql-host=192.168.110.130 --mysql-port=4008 --mysql-user=linzj --mysql-password=linzj --mysql-db=sbtest1 --oltp-num-tables=10 --oltp-table-size=500000 --report-interval=100 --max-requests=0 --oltp-test-mode=complex --oltp-nontrx-mode=select --oltp-read-only=on --max-time=300 --num-threads=16 run > /tmp/130_4008_readonly.log
ssh root@ansible '/usr/bin/ansible all -m shell -a "sh /home/linzj/shell/mysql.sh stop; sh /home/linzj/shell/mysql.sh start"'
sleep 60
sysbench --test=oltp --mysql-host=192.168.110.131 --mysql-port=3306 --mysql-user=linzj --mysql-password=linzj --mysql-db=sbtest1 --oltp-num-tables=10 --oltp-table-size=500000 --report-interval=100 --max-requests=0 --oltp-test-mode=complex --oltp-nontrx-mode=select --oltp-read-only=on --max-time=300 --num-threads=16 run > /tmp/131_3306_readonly.log
ssh root@ansible '/usr/bin/ansible all -m shell -a "sh /home/linzj/shell/mysql.sh stop; sh /home/linzj/shell/mysql.sh start"'
sleep 60
sysbench --test=oltp --mysql-host=192.168.110.130 --mysql-port=4006 --mysql-user=linzj --mysql-password=linzj --mysql-db=sbtest1 --oltp-num-tables=10 --oltp-table-size=500000 --report-interval=100 --max-requests=0 --oltp-test-mode=complex --oltp-nontrx-mode=select --oltp-read-only=off --max-time=300 --num-threads=16 run > /tmp/130_4006_readwrite.log
ssh root@ansible '/usr/bin/ansible all -m shell -a "sh /home/linzj/shell/mysql.sh stop; sh /home/linzj/shell/mysql.sh start"'
sleep 60
sysbench --test=oltp --mysql-host=192.168.110.131 --mysql-port=3306 --mysql-user=linzj --mysql-password=linzj --mysql-db=sbtest1 --oltp-num-tables=10 --oltp-table-size=500000 --report-interval=100 --max-requests=0 --oltp-test-mode=complex --oltp-nontrx-mode=select --oltp-read-only=off --max-time=300 --num-threads=16 run > /tmp/131_3306_readwrite.log这里我通过ansible管理3台MySQL，在做压测前重启3台机器，保证压测结果不受到缓冲的影响。
ansible(192.168.110.130)部署了maxscale中间件，该压测脚本部署在mysql1(192.168.110.131)。分只读和混合读写两种情况压测，只读分别测试130机的4006读写分离端口、4008只读端口和131机的3306数据库端口。
| 只读（开启事务） | |||
| 机器 | 端口 | transactions | response time of 95% |
| maxscale机 | 4006 | 35340 | 582.21ms |
| maxscale机 | 4008 | 123507 | 63.91ms |
| 数据库本机 | 3306 | 80570 | 354.22ms |
| 混合读写（开启事务） | |||
| 机器 | 端口 | transactions | response time of 95% |
| maxscale机 | 4006 | 6899 | 2435.64ms |
| 数据库本机 | 3306 | 6759 | 2651.76ms |
| 只读（关闭事务） | |||
| 机器 | 端口 | transactions | response time of 95% |
| maxscale机 | 4006 | 943008 | 19.34ms |
| maxscale机 | 4008 | 3216914 | 3.48ms |
| 数据库本机 | 3306 | 2338108 | 0.55ms |
| 混合读写（关闭事务） | |||
| 机器 | 端口 | transactions | response time of 95% |
| maxscale机 | 4006 | 1227877 | 8.41ms |
| 数据库本机 | 3306 | 2563155 | 0.51ms |
因为压测时间只有600s，并且由于虚拟机性能的缘故，只开了16个线程进行并发，测试结果可能偏差较大。但是仍然可以总结出一些结论：
1、关闭事务（即autocommit=1）的情况下，通过maxscale访问方式性能远高于直连数据库方式
2、混合读写的情况下，通过maxscale访问方式有一定的性能损耗。
