大型项目mysql5.6主从读写分离搭建（一主三从）

本篇文章记录博主所负责的一个大型项目最近一次遇到主从失效，重新搭建的整个过程。博主可是干了几个小时才搭建好，但是小伙伴们不要怕，其实搭建主从本身是非常简单的；主要还是数据量十几个G还原数据库花费太多时间。

首先，因为博主负责的该项目服务器几十台的规模，所以批量操作博主都已经做成了自动化脚本。如果大家要想看脚本请到前面博主的文章查看：大型项目linux自动化版本发布脚本（shell）之tomcat、nginx服务脚本

以下是详细步骤：

一、停止web应用,接口服务器,mycat

#执行nginx集群下线脚本（主要解决几台nginx转发问题）
sh n_downline_ssh.sh
#停止所有web服务器tomcat
sh t_kill.sh
#停止接口服务器tomcat
Kill -9 接口服务器tomcat进程号
#停止mycat服务
./mycat stop

二、备份主数据库

#备份命令
nohup mysqldump -uxxx -pxxxxx   xxerx_wcc_test > /opt/xxerx/dbbackup/xxerx_20181031.sql 1>myout.out 2>/dev/null &
#由于博主主了脚本执行，此处就直接运行脚本备份
sh t_xxmp_database_backup.sh

三、通知项目公司运维部门的人上传sql到几台从数据库所在服务器（人家是内网，速度快）

四、把三台数据库主从挂载去掉

#需要先分别登录几台从库上mysql命令行
stop slave;
reset slave  all;
show slave status;

五、把三台从数据库的xxery_wcc库删掉,重新创建数据库

#从库sql命令行执行
drop database if exists `xxerx_wcc`;
create database `xxerx_wcc` DEFAULT CHARACTER SET UTF8 COLLATE utf8_general_ci;

六、设置几台从数据库参数

#设置一下参数来提高sql执行速度
set global net_buffer_length=1000000;(经测试无效)
set global max_allowed_packet=1000000000;(经测试无效)
//目标数据库（从库），查看参数设置结果
show variables like 'max_allowed_packet';
show variables like 'net_buffer_length';

#上面的设置可能会没生效，可执行下面登录时设置
mysql -u rxxx -p -e "set global net_buffer_length=1000000; set global max_allowed_packet=1000000000;"

#设置关闭一些数据库校验，提高sql执行速度
SET foreign_key_checks = 0;
SET UNIQUE_CHECKS = 0;
SET AUTOCOMMIT = 0;
SET GLOBAL log_bin_trust_function_creators = 1;

七、重启主库，在主库执行grant命令授权从库挂载 mysql命令:show master status; 记录posion和bin块

#将mysql锁住不写数据
flush tables with read lock;
#重启mysql
service mysql restart;


#主数据库配置授权从库的连接权限
grant replication slave on *.* to 'xxx'@'10.x.x.xx7' identified by 'xxxxxxxxxx@xxx~!@';
grant replication slave on *.* to 'xxx'@'10.x.x.xx1' identified by 'xxxxxxxxxx@xxx~!@';
grant replication slave on *.* to 'xxx'@'10.x.x.xx1' identified by 'xxxxxxxxxx@xxx~!@';
#查看mysql pos位置和bin文件块
show master status;
#执行结果
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000094 |      715 | xxery_wcc    | mysql,test       |                   |
+------------------+----------+--------------+------------------+-------------------+

八、在三台从数据上执行备份的sql文件还原数据库,重启mysql

#mysql>

use xxerx_wcc;
source /opt/xxerx/xxerx_wcc20181031_214314.sql;

--需手动复制函数视图过来(函数、视图同步)

九、将从库校验参数修改回来

SET foreign_key_checks = 1;
SET UNIQUE_CHECKS = 1;
SET AUTOCOMMIT = 1;

十、在从库上执行命令配置主从,并启动：start slave;

#mysql命令
#关闭从库连接
stop slave;
change master to master_host='10.x.x.xxx',master_port=3x06,master_user='xxx',master_password='xxxxxx@xxxx~!@',master_log_file = 'mysql-bin.000094',master_log_pos = 715;
#开启从库连接同步
start slave;
#在主库中执行主库,检查从库是否挂载成功
show processlist \G;
#上一句执行效果
*************************** 1. row ***************************
     Id: 19
   User: root
   Host: 10.x.x.xxx:52739
     db: NULL
Command: Binlog Dump
   Time: 273
  State: Master has sent all binlog to slave; waiting for binlog to be updated
   Info: NULL
*************************** 2. row ***************************
     Id: 20
   User: xoox
   Host: 10.x.x.xxx:xxx06
     db: NULL
Command: Binlog Dump
   Time: 158
  State: Master has sent all binlog to slave; waiting for binlog to be updated
   Info: NULL
*************************** 3. row ***************************
     Id: 21
   User: xoox
   Host: 10.x.x.xxx:3x9xx
     db: NULL
Command: Binlog Dump
   Time: 78
  State: Master has sent all binlog to slave; waiting for binlog to be updated
   Info: NULL
*************************** 4. row ***************************
     Id: 22
   User: xoox
   Host: localhost
     db: NULL
Command: Query
   Time: 0
  State: init
   Info: show processlist
4 rows in set (0.34 sec)

十一、检查从库状态 show slave status. 测试同步是否成功（主库手动加数据看从库是否同步）

#主库执行,解锁主库
unlock tables;
#从库执行,查看从库状态
show slave status\G;

十二、修改mycat配置，重启Mycat（因为从库坏后，我把连接配置修改回了单库支撑线上业务，此处需要修改回读写分离）

cd /opt/xxxx/mycat/conf/
vi  schema.xml
cd /opt/xxxx/bin
./mycat start;

#修改前（读写配置同一台主库）：
<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://org.opencloudb/">
        <schema name="xxerx_wcc" checkSQLschema="false" dataNode="dn1">
        </schema>
        <dataNode name="dn1" dataHost="localhost1" database="xxerx_wcc" />
        <dataHost name="localhost1" maxCon="1000" minCon="10" balance="1"
                writeType="0" dbType="mysql" dbDriver="native" switchType="2"  slaveThreshold="100">
                <heartbeat>show slave status</heartbeat>
                <!-- can have multi master write hosts -->
                <writeHost host="xilon-centos5" url="10.x.x.xxx:3x06" user="xxx"
                        password="xxxxx@xxx~!@">
                <!-- can have multi slave read hosts -->
                <readHost host="xilon-centos5" url="10.x.x.xxx:3x06" user="xxx"
                        password="xxxxx@xxx~!@" />
                </writeHost>
        </dataHost>
</mycat:schema>

#修改后：
<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://org.opencloudb/">
        <schema name="xxerx_wcc" checkSQLschema="false" dataNode="dn1">
        </schema>
        <dataNode name="dn1" dataHost="localhost1" database="xxerx_wcc" />
        <dataHost name="localhost1" maxCon="1000" minCon="10" balance="1"
                writeType="0" dbType="mysql" dbDriver="native" switchType="2"  slaveThreshold="100">
                <heartbeat>show slave status</heartbeat>
                <!-- can have multi master write hosts -->
                <writeHost host="xilon-centos5" url="10.x.x.xxx:3xx6" user="xxx"
                        password="xxxxx@xxx~!@">
                <!-- can have multi slave read hosts -->
                <readHost host="xilon-centos6" url="10.x.x.xxx:3xx6" user="xxx"
                        password="xxxxx@xxx~!@" />
                <readHost host="xilon-centos7" url="10.x.x.xxx:3xx6" user="xxx"
                        password="xxxxx@xxx~!@" />
                <readHost host="xilon-centos8" url="10.x.x.xxx:3xx6" user="xxx"
                        password="xxxxx@xxx~!@" />
                </writeHost>
        </dataHost>
</mycat:schema>

十三、重启web,接口服务器