MySQL备份与恢复之冷备（1）

        用一句话概括冷备，就是把数据库服务，比如MySQL，Oracle停下来，然后使用拷贝、打包或者压缩命令对数据目录进行备份。如果数据出现异常，则可以通过备份数据恢复。冷备一般需要定制计划，比如什么时候做备份，每次对哪些数据进行备份等等。但是由于这样的备份占用过多的空间，对大数据量的环境下不一定适合，故生产环境很少使用。

冷备示意图

冷备实验

第一步，创建测试数据库，插入测试数据

mysql> use larrydb;
Database changed
mysql> show tables;
+-------------------+
| Tables_in_larrydb |
+-------------------+
| access  |
+-------------------+
1 row in set (0.00 sec)

mysql> drop table access;
Query OK,0 rows affected (0.00 sec)

mysql> clear
mysql> show tables;
Empty set (0.00 sec)

mysql> 
mysql> create table class(
 -> cid int,-> cname varchar(30));
Query OK,0 rows affected (0.01 sec)

mysql> show create table class G;
*************************** 1. row ***************************
 Table: class
Create Table: CREATE TABLE `class` (
 `cid` int(11) DEFAULT NULL,`cname` varchar(30) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

ERROR: 
No query specified

mysql> create table stu(
 -> sid int,-> sname varchar(30),-> cid int) engine=myisam;
Query OK,0 rows affected (0.00 sec)

mysql> show create table stu G;
*************************** 1. row ***************************
 Table: stu
Create Table: CREATE TABLE `stu` (
 `sid` int(11) DEFAULT NULL,`sname` varchar(30) DEFAULT NULL,`cid` int(11) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

ERROR: 
No query specified

mysql> insert into class values(1,'linux'),(2,'oracle');
Query OK,2 rows affected (0.00 sec)
Records: 2 Duplicates: 0 Warnings: 0

mysql> desc class;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| cid | int(11) | YES | | NULL | |
| cname | varchar(30) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+
2 rows in set (0.00 sec)

mysql> desc stu;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| sid | int(11) | YES | | NULL | |
| sname | varchar(30) | YES | | NULL | |
| cid | int(11) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

mysql> insert into stu values(1,'larry01',1),'larry02',2);
Query OK,2 rows affected (0.00 sec)
Records: 2 Duplicates: 0 Warnings: 0

mysql> select * from stu;
+------+---------+------+
| sid | sname | cid |
+------+---------+------+
| 1 | larry01 | 1 |
| 2 | larry02 | 2 |
+------+---------+------+
 

第二步，停掉MySQL

[root@serv01 ~]# /etc/init.d/mysqld stop
Shutting down MySQL... SUCCESS! 

 
第三步，创建备份目录，并修改拥有者和所属组

[root@serv01 ~]# mkdir /databackup
[root@serv01 ~]# chown mysql.mysql /databackup/ -R
[root@serv01 ~]# ll /databackup/ -d
drwxr-xr-x. 2 mysql mysql 4096 Sep 10 17:46 /databackup/
[root@serv01 ~]# cd /databackup/
 

第四步，冷备（使用tar命令）

[root@serv01 databackup]# tar -cvPzf mysql01.tar.gz 

 
第五步，测试冷备的数据是否正常，我们删除掉data下的所有数据

[root@serv01 databackup]# rm -rf /usr/local/mysql/data/*

 
第六步，删除所有数据后数据库不能启动

[root@serv01 databackup]# /etc/init.d/mysqld start
Starting MySQL.. ERROR! The server quit without updating PID file (/usr/local/mysql/data/serv01.host.com.pid).

 
第七步，恢复数据（使用tar命令）

[root@serv01 databackup]# tar -xvPf mysql01.tar.gz 

 
第八步，启动MySQL，然后登录MySQL，查看数据是否丢失，如果数据正常代表冷备成功

[root@serv01 databackup]# /etc/init.d/mysqld start
Starting MySQL.. SUCCESS! 

[root@serv01 ~]# mysql
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 1
Server version: 5.5.29-log Source distribution

Copyright (c) 2000,2012,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.

mysql> use larrydb;
Database changed
mysql> select * from class;
+------+--------+
| cid | cname |
+------+--------+
| 1 | linux |
| 2 | oracle |
+------+--------+
2 rows in set (0.00 sec)

mysql> select * from stu;
+------+---------+------+
| sid | sname | cid |
+------+---------+------+
| 1 | larry01 | 1 |
| 2 | larry02 | 2 |
+------+---------+------+
2 rows in set (0.00 sec)

以上就是实现MySQL冷备的全部过程，大家对冷备有没有了大概的了解，希望这篇文章可以对大家的学习有所帮助。

（编辑：李大同）

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