用一句話概括冷備，就是把數據庫服務，比如MySQL，Oracle停下來，然后使用拷貝、打包或者壓縮命令對數據目錄進行備份。如果數據出現異常，則可以通過備份數據恢復。冷備一般需要定制計劃，比如什么時候做備份，每次對哪些數據進行備份等等。但是由于這樣的備份占用過多的空間，對大數據量的環(huán)境下不一定適合，故生產環(huán)境很少使用。

冷備示意圖

冷備實驗

第一步，創(chuàng)建測試數據庫，插入測試數據

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，創(chuàng)建備份目錄，并修改擁有者和所屬組

[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，冷備（使用tar命令）

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

第五步，測試冷備的數據是否正常，我們刪除掉data下的所有數據

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

第六步，刪除所有數據后數據庫不能啟動

[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，恢復數據（使用tar命令）

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

第八步，啟動MySQL，然后登錄MySQL，查看數據是否丟失，如果數據正常代表冷備成功

[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)

以上就是實現MySQL冷備的全部過程，大家對冷備有沒有了大概的了解，希望這篇文章可以對大家的學習有所幫助。

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