一、公司Mysql环境

#1. 目前公司Mysql只做了主从

#2. Mysql数据库版本：Percona-Server-server-56-5.6.20-rel68.0.el6.x86_64.rpm

二、Mysql从库的问题

Mysql从库一直都用命令启动：mysqld_safe --defaults-file=/etc/my.cnf & 。用/etc/init.d/mysql启动脚本一直报错。最郁闷的是在错误日志里没有记录启动错误信息。

我忍受了大半年的命令启动，终于不想再忍下去了。

之前一直以为/etc/my.cnf有问题，再尝试大半天时间后没有解决。 我决定还是卸载之前的mysql，重新安装mysql

卸载准备工作：

tar zcvf mysql.tar.gz  /data/mysql        # 备份mysql数据目录

mv  /etc/my.cnf  /etc/my.cnf.ori

删除

rm -rf /data/mysql

rpm -e Percona-Server-server-56-5.6.20

rpm -e Percona-Server-client-56-5.6.20

rpm -e Percona-Server-shared-56-5.6.20

安装

rpm -ivhPercona-Server-client-56-5.6.20-rel68.0.el6.x86_64.rpm Percona-Server-server-56-5.6.20-rel68.0.el6.x86_64.rpm Percona-Server-shared-56-5.6.20-rel68.0.el6.x86_64.rpm

#############################################

我以为会重新生成默认的/etc/my.cnf，发现没有。又找了一台服务器安装了mysql，导出默认的/etc/my.cnf

###################################

重装之后，在不修改默认配置是可以正常启动的。但只要导入生产/etc/my.cnf配置后又是错误

[root@###### ~]# service mysql start

Starting MySQL (Percona Server).The server quit without upd[FAILED]D file (/home/mysql/mysql.pid).

再改回默认的/etc/my.cnf正常。 只要修改默认配置就出错。（真心折腾啊）

[mysqld]
datadir=/data/mysql      # 默认/var/lib/mysql
socket=/data/mysql/mysql.sock  # 默认/var/lib/mysql/mysql.sock
user=mysql
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
[mysqld_safe]
log-error=/data/mysqld.log   # 默认/var/log/mysqld.log
pid-file=/data/mysqld/mysqld.pid   #/var/run/mysqld/mysqld.pid

幸运的是此次有了错误日志

[root@###### data]# !tail

tail -20 /var/log/mysqld.log

160524 14:07:20 mysqld_safe Starting mysqlddaemon with databases from /data/mysql

2016-05-24 14:07:20 13213 [Warning] Can't create test file/data/mysql/mfs-data3.lower-test

2016-05-24 14:07:20 13213 [Warning] Can'tcreate test file /data/mysql/mfs-data3.lower-test

/usr/sbin/mysqld: File'/data/mysql/mysql-bin.index' not found (Errcode: 13 - Permission denied)

2016-05-24 14:07:20 13213 [ERROR] Aborting

花了点时间找到该错误是由selinux引起的。 关闭selinux

setenforce 0

sed -i "s#enforcing#disabled#g"  /etc/selinux/config

再次启动

[root@###### mysql]# service mysql start

Starting MySQL (Percona Server)..The server quit without up[FAILED]ID file (/home/mysql/mysql.pid).

[root@yyqdb02 mysql]# cat log/mysql-error.log

160524 14:31:37 mysqld_safe Starting mysqld daemon with databases from /home/mysql/data/

2016-05-24 14:31:38 6632 [Warning] Can't create test file /data/mysql/data/*.lower-test

2016-05-24 14:31:38 6632 [Warning] Can't create test file /data/mysql/data/*.lower-test

/usr/sbin/mysqld: Can't change dir to '/data/mysql/data/' (Errcode: 2 - No such file or directory)

2016-05-24 14:31:38 6632 [ERROR] Aborting

思路：创建所需的目录

mkdir /data/mysql/{data,log} -p

发现问题依旧。后来仔细检查了生产的/etc/my.cnf

datadir                        = /data/mysql/data/

终于找到原因了：

之前创建新实例命令是：mysql_install_db  --user=mysql --datadir=/home/mysql

改为                mysql_install_db  --user=mysql --datadir=/data/mysql/data

再次使用/etc/init.d/mysql restart终于成功了。

[root@###### data]# service mysql restart

Shutting down MySQL (Percona Server).. SUCCESS!

Starting MySQL (Percona Server).. SUCCESS!

三、恢复从库身份

之前主库一直有备份，所以不用担心在主库工作时间做主从同步了。

将主备份拷贝到从

[root@##### tmp]# scp 192.168.2.105:/data/bak/all_2016-05-22.sql.gz ./

root@172.30.1.10's password:

all_2016-05-22.sql.gz                                                                                                                                                                                100%   21MB 20.9MB/s   00:00

[root@##### tmp]# ls

all_2016-05-22.sql.gz

[root@yyqdb02 tmp]# gzip -d all_2016-05-22.sql.gz

[root@yyqdb02 tmp]# less all_2016-05-22.sql

-- MySQL dump 10.13 Distrib 5.6.20-68.0, for Linux (x86_64)

--

-- Host: localhost   Database:

-- ------------------------------------------------------

-- Server version      5.6.20-68.0-log

/*!40101 SET@OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;

/*!40101 SET@OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;

/*!40101 SET@OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;

/*!40101 SET NAMES utf8 */;

/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;

/*!40103 SET TIME_ZONE='+00:00' */;

/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS,UNIQUE_CHECKS=0 */;

/*!40014 SET@OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;

/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE,SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;

/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0*/;

--

-- Position to start replication or point-in-timerecovery from

--

-- CHANGE MASTER TO MASTER_LOG_FILE='mysql-bin.000042', MASTER_LOG_POS=142703;

--

-- Current Database: `decorate`

--

[root@##### tmp]# service mysql status    # mysql服务器运行着

MySQL (Percona Server) running (17022)                     [  OK  ]

[root@yyqdb02 tmp]#mysql -uroot -p < all_2016-05-22.sql

Enter password:

[root@##### tmp]# mysql -uroot -p     # 由于没有flush privileges，密码为空。害我输了好几次导入后的root密码

Enter password:

ERROR 1045 (28000): Access denied for user'root'@'localhost' (using password: YES)

[root@###### tmp]# mysql -uroot -p

Enter password:

Welcome to the MySQL monitor.  Commands end with ; or \g.

Your MySQL connection id is 5

Server version: 5.6.20-68.0-log Percona Server (GPL),Release 68.0, Revision 656

Copyright (c) 2009-2014 Percona LLC and/or itsaffiliates

Copyright (c) 2000, 2014, Oracle and/or its affiliates.All rights reserved.

Oracle is a registered trademark of Oracle Corporationand/or its

affiliates. Other names may be trademarks of theirrespective

owners.

Type 'help;' or '\h' for help. Type '\c' to clear thecurrent input statement.

mysql> flushprivileges;   # 刷新下

Query OK, 0 rows affected (0.00 sec)

mysql> changemaster tomaster_host='192.168.2.105',master_port=3306,master_user='rep',master_password='password',MASTER_LOG_FILE='mysql-bin.000042',MASTER_LOG_POS=142703;    # 此命令已经可以盲打了

Query OK, 0 rows affected, 2 warnings (0.01 sec)

mysql> start slave;

Query OK, 0 rows affected (0.00 sec)

mysql> showslave status\G

*************************** 1. row***************************

Slave_IO_State: Waiting for master to send event

Master_Host: 172.30.1.10

Master_User: slave

Master_Port: 3306

Connect_Retry: 60

Master_Log_File: mysql-bin.000042

Read_Master_Log_Pos: 302454

Relay_Log_File: relay-bin.000002

Relay_Log_Pos: 160034

Relay_Master_Log_File: mysql-bin.000042

             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: 302454

Relay_Log_Space: 160201

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: 1

Master_UUID: c73c4373-34fd-11e4-a1bd-b82a72cf2c9f

Master_Info_File: /home/mysql/data/master.info

                    SQL_Delay: 0

SQL_Remaining_Delay: NULL

Slave_SQL_Running_State: Slave has read all relay log; waiting for theslave I/O thread to update it

Master_Retry_Count: 86400

Master_Bind:

Last_IO_Error_Timestamp:

Last_SQL_Error_Timestamp:

Master_SSL_Crl:

Master_SSL_Crlpath:

Retrieved_Gtid_Set:

Executed_Gtid_Set:

Auto_Position: 0

1 row in set (0.00 sec)

####至此，全部搞定。 主从2分钟搞定，而且没出错，太顺利了，让我无法接受啊。