MySQL备份与恢复之热拷贝

清疚 2022-09-18 05:59 14阅读 0赞

## 一 热拷贝 ##

在上一篇文章中我们提到热备，热备也就是在MySQL或者其他数据库服务在运行的情况下进行备份。本文分享另外一种备份的方法，也就是热拷贝。热拷贝跟热备很类似，只不过热备使用mysqldump命令，热拷贝使用mysqlhotcopy命令。热拷贝的优势在于支持服务运行中进行备份，速度快，性能好；劣势在于只能备份MyIsam的表，无法备份InnoDB的表。所以在生产环境中应该酌情使用。

## 二 示意图 ##

![SouthEast][]

## 三 热备模拟 ##

第一步，热拷贝

>     [root@serv01 databackup]# mysqlhotcopy -uroot -p123456 --database larrydb > larrydb_hostcopy.sql
>     Can't locate DBI.pm in @INC (@INC contains: /usr/local/lib64/perl5 /usr/local/share/perl5 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5 .) at /usr/local/mysql/bin/mysqlhotcopy line 25.
>     BEGIN failed--compilation aborted at /usr/local/mysql/bin/mysqlhotcopy line 25.

第二步，报错。因为这个命令是用perl写的或者此命令需要perl支持，所以需要安装perl

>     [root@serv01 databackup]# yum install perl* -y

第三步，对数据库larrydb热拷贝

>     [root@serv01 databackup]# mysqlhotcopy --help
>     
>     #第一种写法
>     [root@serv01 databackup]# mysqlhotcopy --user=root --password=123456 larrydb /databackup/
>     
>     #第二种写法
>     [root@serv01 databackup]# mysqlhotcopy -u root -p 123456 larrydb /databackup/
>     
>     Flushed 2 tables with read lock (`larrydb`.`class`, `larrydb`.`stu`) in 0 seconds.
>     Locked 0 views () in 0 seconds.
>     Copying 5 files...
>     Copying indices for 0 files...
>     Unlocked tables.
>     mysqlhotcopy copied 2 tables (5 files) in 0 seconds (0 seconds overall).

第四步，模拟数据丢失

>     [root@serv01 databackup]# ll larrydb
>     total 36
>     -rw-rw----. 1 mysql mysql 8590 Sep 10 19:07 class.frm
>     -rw-rw----. 1 mysql mysql   65 Sep 10 19:07 db.opt
>     -rw-rw----. 1 mysql mysql 8618 Sep 10 19:07 stu.frm
>     -rw-rw----. 1 mysql mysql   48 Sep 10 19:07 stu.MYD
>     -rw-rw----. 1 mysql mysql 1024 Sep 10 19:07 stu.MYI
>     
>     mysql> use larrydb;
>     Database changed
>     mysql> show tables;
>     +-------------------+
>     | Tables_in_larrydb |
>     +-------------------+
>     | class             |
>     | stu               |
>     +-------------------+
>     2 rows in set (0.00 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> 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=latin1
>     1 row in set (0.00 sec)
>     
>     ERROR: 
>     
>     mysql> drop table class,stu;
>     Query OK, 0 rows affected (0.01 sec)
>     
>     mysql> show tables;
>     Empty set (0.00 sec)
>       
>     #这样删除会出错，不要这样删除
>     [root@serv01 databackup]# rm -rf /usr/local/mysql/data/larrydb/*
>     [root@serv01 databackup]# rm -rf /usr/local/mysql/data/larrydb/

第五步，恢复数据

>     [root@serv01 databackup]# cp larrydb /usr/local/mysql/data/ -arvf
>     `larrydb' -> `/usr/local/mysql/data/larrydb'
>     `larrydb/stu.MYI' -> `/usr/local/mysql/data/larrydb/stu.MYI'
>     `larrydb/stu.MYD' -> `/usr/local/mysql/data/larrydb/stu.MYD'
>     `larrydb/stu.frm' -> `/usr/local/mysql/data/larrydb/stu.frm'
>     `larrydb/db.opt' -> `/usr/local/mysql/data/larrydb/db.opt'
>     `larrydb/class.frm' -> `/usr/local/mysql/data/larrydb/class.frm'
>     
>     mysql> use larrydb;
>     Database changed
>     mysql> show tables;
>     +-------------------+
>     | Tables_in_larrydb |
>     +-------------------+
>     | class             |
>     | stu               |
>     +-------------------+
>     2 rows in set (0.00 sec)
>     
>     mysql> select * from class;
>     ERROR 1146 (42S02): Table 'larrydb.class' doesn't exist
>     mysql> select * from stu;
>     +------+---------+------+
>     | sid  | sname   | cid  |
>     +------+---------+------+
>     |    1 | larry01 |    1 |
>     |    2 | larry02 |    2 |
>     +------+---------+------+
>     2 rows in set (0.00 sec)
>     
>     mysql> drop database larrydb;
>     Query OK, 2 rows affected (0.00 sec)
>     
>     #再次导入
>     [root@serv01 databackup]# mysql -uroot -p123456 < larrydb.sql
>     
>     mysql> use larrydb;
>     Database changed
>     mysql> show tables;
>     +-------------------+
>     | Tables_in_larrydb |
>     +-------------------+
>     | class             |
>     | stu               |
>     +-------------------+
>     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)
>     
>     mysql> select * from class;
>     +------+--------+
>     | cid  | cname  |
>     +------+--------+
>     |    1 | linux  |
>     |    2 | oracle |
>     +------+--------+
>     2 rows in set (0.00 sec)

## 四 相关阅读 ##

*  [MySQL备份与恢复之冷备][MySQL]
 *  [MySQL备份与恢复之真实环境使用冷备][MySQL 1]
 *  [MySQL备份与恢复之热备][MySQL 2]

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>       微信公众平台：JustOracle（微信号：justoracle）
>       数据库技术交流群：336882565（加群时验证 From CSDN XXX）
>       All is well
>       2013年11月10日
>       By Larry Wen

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[SouthEast]: /images/20220828/46d6868c671d45f09d9e23eaa6b529db.png
[MySQL]: http://blog.csdn.net/justdb/article/details/14053345
[MySQL 1]: http://blog.csdn.net/justdb/article/details/14101561
[MySQL 2]: http://blog.csdn.net/justdb/article/details/14644549