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),(2,'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。
