一 什么是冷备

       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。

二 冷备示意图

三 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 |
+-----