MySQL备份与恢复之热备

雨点打透心脏的1/2处 2022-09-18 05:00 272阅读 0赞

## 一 热备 ##

在上两篇文章（[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]）中，我们提到了冷备和真实环境中使用冷备。那从这篇文章开始我们看下热备。显然热备和冷备是两个相对的概念，冷备是把数据库服务，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；那么我们很容易想到热备就是在MySQL或者其他数据库服务在运行的情况下进行备份。但是，这里存在一个问题，因为生产库在运行的情况下，有对该库的读写，读写频率有可能高，也可能低，不管频率高低，总会就会造成备份出来的数据和生产库中的数据不一致的情况。热备这段时间，其他人不可以操作是不现实的，因为你总不可能终止用户访问Web程序。要解决这个问题，可以采用指定备份策略，比如哪个时间段进行备份，备份哪些数据等等，总之，保证数据的完整性和一致性，切记，**备份重于一切！！！**

热备采用的是使用mysqldump命令进行备份，此工具是MySQL内置的备份和恢复工具，功能强大，它可以对整个库进行备份，可以对多个库进行备份，可以对单张表或者某几张表进行备份。但是无法同时备份多个库多个表，只有分开备份。下面我们看下热备的示意图，并进行热备模拟。

## 二 示意图 ##

![SouthEast][]

## 三 热备模拟 ##

### **对单个库进行备份** ###

第一步，移除LVM快照。（如果没有创建，忽略此步）

>     [root@serv01 data]# lvremove /dev/data/smydata 
>     Do you really want to remove active logical volume smydata? [y/n]: y
>       Logical volume "smydata" successfully removed

第二步，设置MySQL的密码

>     mysql> set password=password("123456");
>     Query OK, 0 rows affected (0.00 sec)

第三步，查看MySQL是否启动。因为是热备，所以要求MySQL服务启动

>     [root@serv01 data]# /etc/init.d/mysqld status
>      SUCCESS! MySQL running (2664)

第四步，导出单个数据库

>     [root@serv01 data]# cd /databackup/
>     
>     #本质是导出为SQL
>     [root@serv01 databackup]# mysqldump -uroot -p123456 --database larrydb
>     -- MySQL dump 10.13  Distrib 5.5.29, for Linux (x86_64)
>     --
>     -- Host: localhost    Database: larrydb
>     -- ------------------------------------------------------
>     -- Server version 5.5.29-log
>     
>     /*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
>     /*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
>     /*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
>     /*!40101 SET NAMES utf8 */;
>     /*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
>     /*!40103 SET TIME_ZONE='+00:00' */;
>     /*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
>     /*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
>     /*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
>     /*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
>     
>     --
>     -- Current Database: `larrydb`
>     --
>     
>     CREATE DATABASE /*!32312 IF NOT EXISTS*/ `larrydb` /*!40100 DEFAULT CHARACTER SET latin1 */;
>     
>     USE `larrydb`;
>     
>     --
>     -- Table structure for table `class`
>     --
>     
>     DROP TABLE IF EXISTS `class`;
>     /*!40101 SET @saved_cs_client     = @@character_set_client */;
>     /*!40101 SET character_set_client = utf8 */;
>     CREATE TABLE `class` (
>       `cid` int(11) DEFAULT NULL,
>       `cname` varchar(30) DEFAULT NULL
>     ) ENGINE=InnoDB DEFAULT CHARSET=latin1;
>     /*!40101 SET character_set_client = @saved_cs_client */;
>     
>     --
>     -- Dumping data for table `class`
>     --
>     
>     LOCK TABLES `class` WRITE;
>     /*!40000 ALTER TABLE `class` DISABLE KEYS */;
>     INSERT INTO `class` VALUES (1,'linux'),(2,'oracle');
>     /*!40000 ALTER TABLE `class` ENABLE KEYS */;
>     UNLOCK TABLES;
>     
>     --
>     -- Table structure for table `stu`
>     --
>     
>     DROP TABLE IF EXISTS `stu`;
>     /*!40101 SET @saved_cs_client     = @@character_set_client */;
>     /*!40101 SET character_set_client = utf8 */;
>     CREATE TABLE `stu` (
>       `sid` int(11) DEFAULT NULL,
>       `sname` varchar(30) DEFAULT NULL,
>       `cid` int(11) DEFAULT NULL
>     ) ENGINE=MyISAM DEFAULT CHARSET=latin1;
>     /*!40101 SET character_set_client = @saved_cs_client */;
>     
>     --
>     -- Dumping data for table `stu`
>     --
>     
>     LOCK TABLES `stu` WRITE;
>     /*!40000 ALTER TABLE `stu` DISABLE KEYS */;
>     INSERT INTO `stu` VALUES (1,'larry01',1),(2,'larry02',2);
>     /*!40000 ALTER TABLE `stu` ENABLE KEYS */;
>     UNLOCK TABLES;
>     /*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */;
>     
>     /*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
>     /*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;
>     /*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;
>     /*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
>     /*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
>     /*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;
>     /*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;
>     
>       Dump completed on 2013-09-10 18:56:06
>     
>     #将输出结果保存到文件中
>     [root@serv01 databackup]# mysqldump -uroot -p123456 --database larrydb > larrydb.sql

第五步，模拟数据丢失，进入MySQL，删除数据库

>     [root@serv01 data]# mysql -uroot -p123456
>     Welcome to the MySQL monitor.  Commands end with ; or \g.
>     Your MySQL connection id is 4
>     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> show databases;
>     +--------------------+
>     | Database           |
>     +--------------------+
>     | information_schema |
>     | crm                |
>     | game               |
>     | hello              |
>     | larrydb            |
>     | mnt                |
>     | mysql              |
>     | performance_schema |
>     | test               |
>     +--------------------+
>     9 rows in set (0.00 sec)
>     
>     mysql> drop database larrydb;
>     Query OK, 2 rows affected (0.01 sec)
>     
>     mysql> show databases;
>     +--------------------+
>     | Database           |
>     +--------------------+
>     | information_schema |
>     | crm                |
>     | game               |
>     | hello              |
>     | mnt                |
>     | mysql              |
>     | performance_schema |
>     | test               |
>     +--------------------+
>     8 rows in set (0.00 sec)
>     
>     mysql> exit
>     Bye

第六步，导入数据

>     [root@serv01 databackup]# mysql -uroot -p123456 <larrydb.sql

第七步，登录MySQL，查看数据是否正常

>     [root@serv01 data]# mysql -uroot -p123456
>     Welcome to the MySQL monitor.  Commands end with ; or \g.
>     Your MySQL connection id is 6
>     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> show database;
>     ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'database' at line 1
>     mysql> show databases;
>     +--------------------+
>     | Database           |
>     +--------------------+
>     | information_schema |
>     | crm                |
>     | game               |
>     | hello              |
>     | larrydb            |
>     | mnt                |
>     | mysql              |
>     | performance_schema |
>     | test               |
>     +--------------------+
>     9 rows in set (0.00 sec)
>     
>     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)

### **对多个库进行备份** ###

第一步，查看有哪些数据库

>     mysql> show databases;
>     +--------------------+
>     | Database           |
>     +--------------------+
>     | information_schema |
>     | crm                |
>     | game               |
>     | hello              |
>     | larrydb            |
>     | mnt                |
>     | mysql              |
>     | performance_schema |
>     | test               |
>     +--------------------+
>     9 rows in set (0.00 sec)
>     mysql> use game;
>     Database changed
>     mysql> show tables;
>     +----------------+
>     | Tables_in_game |
>     +----------------+
>     | country        |
>     | fight          |
>     | hero           |
>     +----------------+
>     3 rows in set (0.00 sec)
>     
>     mysql> select * from country;
>     +-----+---------+----------+
>     | cno | cname   | location |
>     +-----+---------+----------+
>     |  10 | caowei  | luoyang  |
>     |  20 | shuhan  | chengdou |
>     |  30 | sunwu   | nanjing  |
>     |  40 | houhan  | luoyang  |
>     |  50 | beisong | kaifeng  |
>     |  60 | 魏国    | 洛阳     |
>     +-----+---------+----------+
>     6 rows in set (0.00 sec)

第二步，备份多个库

>     [root@serv01 databackup]# mysqldump -uroot -p123456 --databases larrydb game > larrydb_game.sql
>     [root@serv01 databackup]# ll larrydb_game.sql 
>     -rw-r--r--. 1 root root 6159 Sep 10 19:05 larrydb_game.sql

第三步，模拟数据丢失。

>     mysql> drop database game;
>     Query OK, 3 rows affected (0.01 sec)
>     
>     mysql> drop database larrydb;
>     Query OK, 2 rows affected (0.00 sec)
>     mysql> use crm;
>     Database changed
>     mysql> show tables;
>     +---------------+
>     | Tables_in_crm |
>     +---------------+
>     | test          |
>     +---------------+
>     1 row in set (0.00 sec)
>     
>     mysql> select * from test;
>     Empty set (0.00 sec)
>     
>     mysql> drop database crm;
>     Query OK, 1 row affected (0.00 sec)

第四步，恢复数据

>     [root@serv01 databackup]# mysql -uroot -p123456 < larrydb_game.sql

第五步，查看数据是否正常

>     [root@serv01 data]# mysql -uroot -p123456
>     Welcome to the MySQL monitor.  Commands end with ; or \g.
>     Your MySQL connection id is 9
>     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> show databases;
>     +--------------------+
>     | Database           |
>     +--------------------+
>     | information_schema |
>     | game               |
>     | hello              |
>     | larrydb            |
>     | mnt                |
>     | mysql              |
>     | performance_schema |
>     | test               |
>     +--------------------+
>     8 rows in set (0.00 sec)
>     
>     mysql> use game;
>     Database changed
>     mysql> select * from country;
>     +-----+---------+----------+
>     | cno | cname   | location |
>     +-----+---------+----------+
>     |  10 | caowei  | luoyang  |
>     |  20 | shuhan  | chengdou |
>     |  30 | sunwu   | nanjing  |
>     |  40 | houhan  | luoyang  |
>     |  50 | beisong | kaifeng  |
>     |  60 | 魏国    | 洛阳     |
>     +-----+---------+----------+
>     6 rows in set (0.00 sec)
>     
>     mysql> use larrydb;
>     Database changed
>     mysql> select * from class;
>     +------+--------+
>     | cid  | cname  |
>     +------+--------+
>     |    1 | linux  |
>     |    2 | oracle |
>     +------+--------+
>     2 rows in set (0.00 sec)

### **备份所有的库** ###

>     [root@serv01 databackup]# mysqldump --help | grep all-database
>     OR     mysqldump [OPTIONS] --all-databases [OPTIONS]
>       -A, --all-databases Dump all the databases. This will be same as --databases
>                           --databases= or --all-databases), the logs will be
>                           --all-databases or --databases is given.
>     all-databases                     FALSE
>     
>     [root@serv01 databackup]# mysqldump -uroot -p123456 --all-databases > all_databases.sql
>     [root@serv01 databackup]# ll all_databases.sql -h
>     -rw-r--r--. 1 root root 506K Sep 10 19:16 all_databases.sql

### **备份某张表或者某几张表** ###

第一步，备份某张表和某几张表

>     [root@serv01 databackup]# mysqldump game hero country -uroot -p123456 > game_hero_country.sql
>     [root@serv01 databackup]# ll game_hero_country.sql 
>     -rw-r--r—. 1 root root 3955 Sep 10 19:11 game_hero_country.sql

第二步，模拟数据丢失

>     mysql> use game;
>     Database changed
>     mysql> show tables;
>     +----------------+
>     | Tables_in_game |
>     +----------------+
>     | country        |
>     | fight          |
>     | hero           |
>     +----------------+
>     3 rows in set (0.00 sec)
>     
>     mysql> drop table hero;
>     Query OK, 0 rows affected (0.00 sec)
>     
>     mysql> drop table country;
>     Query OK, 0 rows affected (0.00 sec)

第三步，查看数据是否正常

>     [root@serv01 databackup]# mysql -uroot -p123456 < game_hero_country.sql 
>     ERROR 1046 (3D000) at line 22: No database selected
>     [root@serv01 databackup]# mysql -uroot -p123456 --database game < game_hero_country.sql 
>     
>     [root@serv01 databackup]# mysql -uroot -p123456 -e "select * from game.country"
>     +-----+---------+----------+
>     | cno | cname   | location |
>     +-----+---------+----------+
>     |  10 | caowei  | luoyang  |
>     |  20 | shuhan  | chengdou |
>     |  30 | sunwu   | nanjing  |
>     |  40 | houhan  | luoyang  |
>     |  50 | beisong | kaifeng  |
>     |  60 | 魏国    | 洛阳     |
>     +-----+---------+----------+

## 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]

>     我的邮箱：wgbno27@163.com   新浪微博：@jutdb         
>       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9日
>       By Larry Wen

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[MySQL]: http://blog.csdn.net/justdb/article/details/14053345
[MySQL 1]: http://blog.csdn.net/justdb/article/details/14101561
[SouthEast]: /images/20220828/38ecb0d859c745519e66661c4a7c9c50.png