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简介
Part1: 写在最前
在之前的博文中有说到 MaxScale，作为中间件，配合 MHA 使用或者主从使用可实现读写分离和负载均衡，今天简单介绍下 MaxScale 作为 Binlog Server 来减少主从延迟的问题；MySQL 的主从架构中，链式拓扑的架构比较容易出现主从延迟的问题。本文着重介绍 MaxScale 作为 Binlog Server 是如何降低主从延迟的。
MaxScale 配合 MHA 请移步至：http://www.linuxidc.com/Linux/2016-11/136969.htm
Part2: 本文环境
HE1:192.168.1.248 slave
HE3:192.168.1.250 master
HE4:192.168.1.251 maxscale
架构演示
实战
Part1: 安装 maxscale
[root@HE4 ~]# yum -y install maxscale-2.0.1-2.CentOS.6.x86_64.rpm
[root@HE4 ~]# mkdir -p /data/binlog
[root@HE4 ~]# useradd maxscale
[root@HE4 ~]# chown -R maxscale. /data/binlog
[root@HE4 ~]# cat /etc/maxscale.cnf
[maxscale]
threads=1
## 根据 CPU 核数设置
[Replication]
type=service
router=binlogrouter
user=mysync
passwd=MANAGER
# 使用主库上的 repl 复制账号
# 权限：
# GRANT REPLICATION SLAVE,REPLICATION CLIENT ON *.* TO ‘repl’@’%’ IDENTIFIED BY ‘repl’;
router_options=server_id=1251,heartbeat=30,binlogdir=/data/binlog,transaction_safety=1,mariadb10-compatibility=1,send_slave_heartbeat=1
# server_id 设置 maxscale 的，记得不能与主和从库重复，要唯一
# heartbeat=30 秒，意思为当 maxscale 在 30 秒内没有接收到主库推送的 binlog 日志，发送心跳检查
# binlogdir 设置接收 binlog 的存放路径，目录属性 chown -R maxscale.maxscale /data/binlog
# transaction_safety= 1 此参数用于启用 binlog 日志中的不完整事务检测。当 MariaDB MaxScale 启动时，如果当前 binlog 文件已损坏或找到不完整的事务，则可能会出现错误消息。在正常工作期间，binlog 事件不会分配到从库，直到事务已经提交。默认值为 off，设置 transaction_safety = on 以启用不完全事务检测。
# send_slave_heartbeat= 1 开启心跳检查
[Replication Listener]
type=listener
service=Replication
protocol=MySQLClient
port=5308
# 后端的从库 CHANGE MASTER TO 这个端口，默认 5308
[CLI]
type=service
router=cli
[CLI Listener]
type=listener
service=CLI
protocol=maxscaled
port=6603
Part2: 启动 Maxscale
[root@HE4 ~]# /etc/init.d/maxscale start
Starting MaxScale: maxscale (pid 16680) is running… [OK]
[root@HE4 ~]# /etc/init.d/maxscale status
Checking MaxScale status: MaxScale (pid 16680) is running.[OK]
Part2: 从库配置
[root@HE1 ~]# mysql -umysync -pMANAGER -h192.168.1.251 -P5308
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MySQL connection id is 3196
Server version: 10.0.0 2.0.1-maxscale
Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.
Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the current input statement.
MySQL [(none)]> CHANGE MASTER TO MASTER_HOST=’192.168.1.250′,MASTER_USER=’mysync’,MASTER_PASSWORD=’MANAGER’,MASTER_PORT=3306,MASTER_LOG_FILE=’mysql-bin.000005′,MASTER_LOG_POS=20;
ERROR 1234 (42000): Can not set MASTER_LOG_POS to 20: Permitted binlog pos is 4. Specified master_log_file=mysql-bin.000005
MySQL [(none)]> CHANGE MASTER TO MASTER_HOST=’192.168.1.250′,MASTER_USER=’mysync’,MASTER_PASSWORD=’MANAGER’,MASTER_PORT=3306,MASTER_LOG_FILE=’mysql-bin.000005′,MASTER_LOG_POS=4;
MySQL [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)
这里可以看出，Maxscale binlog server 只能从位置 4 开始配置
配置好后，在 /data/binlog 下生成的 binlog 文件
[root@HE4 ~]# cd /data/binlog/
[root@HE4 binlog]# ls
cache master.ini mysql-bin.000003
Part2: 主库配置
[root@HE3 ~]# mysql -uroot -p
Enter password:
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 7
Server version: 10.1.16-MariaDB MariaDB Server
Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.
Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the current input statement.
MariaDB [(none)]> show master status;
+——————+———-+————–+——————+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+——————+———-+————–+——————+
| mysql-bin.000005 | 652 | | |
+——————+———-+————–+——————+
1 row in set (0.00 sec)
MariaDB [(none)]> grant replication client,replication slave on *.* to ‘mysync’@’192.168.1.%’ identified by ‘MANAGER’;
MariaDB [(none)]>flush privileges;
Part3: 主从配置
从库指向 binlogserver
[root@HE1 ~]# mysql -uroot -pMANAGER
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 5
Server version: 10.1.16-MariaDB MariaDB Server
Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.
Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the current input statement.
MariaDB [(none)]> CHANGE MASTER TO MASTER_HOST=’192.168.1.251′,MASTER_USER=’mysync’,MASTER_PASSWORD=’MANAGER’,MASTER_PORT=5308,MASTER_LOG_FILE=’mysql-bin.000005′,MASTER_LOG_POS=652;
Query OK, 0 rows affected (0.02 sec)
MariaDB [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.1.251
Master_User: mysync
Master_Port: 5308
Connect_Retry: 60
Master_Log_File: mysql-bin.000005
Read_Master_Log_Pos: 652
Relay_Log_File: mysql-relay-bin.000002
Relay_Log_Pos: 537
Relay_Master_Log_File: mysql-bin.000005
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 652
Relay_Log_Space: 835
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 1250
Master_SSL_Crl:
Master_SSL_Crlpath:
Using_Gtid: No
Gtid_IO_Pos:
Replicate_Do_Domain_Ids:
Replicate_Ignore_Domain_Ids:
Parallel_Mode: conservative
1 row in set (0.00 sec)
——总结——
生产环境中，大多采用的是一主多从架构，例如星状拓扑和链式拓扑，星状拓扑在从库过多的情况下，会增加主库的 io 压力，而链式拓扑虽然缓解了主库的网络 IO 压力，但其缺点是：二级 Slave 得到最新的数据，需要再经过一层的复制才到达，期间的延迟比一主多从架构要大。而采用 maxscale binlog server 则避免了这类问题。由于笔者的水平有限，编写时间也很仓促，文中难免会出现一些错误或者不准确的地方，不妥之处恳请读者批评指正。
本文永久更新链接地址 ：http://www.linuxidc.com/Linux/2016-12/137892.htm
