MySQL备份与恢复之热备（3）

在上两篇文章（MySQL备份与恢复之冷备，MySQL备份与恢复之真实环境使用冷备）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。
示意图

热备模拟

1、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

1 2	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

1 2	[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

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

1	[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

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

1	[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

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 |

+-----+---------+----------+

通过这两天关于MySQL热备和冷备的学习，大家是不是对MySQL备份与恢复的了解更加深入了，不管是冷备还是热备其目的都是一致的保证数据的完整性和一致性，切记，备份重于一切！！！

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MySQL备份与恢复之热备（3）