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)
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[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
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第二步,设置MySQL的密码
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mysql> set password = password ( "123456" );
Query OK, 0 rows affected (0.00 sec)
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第三步,查看MySQL是否启动。因为是热备,所以要求MySQL服务启动
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[root@serv01 data]# /etc/init.d/mysqld status
SUCCESS! MySQL running (2664)
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第四步,导出单个数据库
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[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
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第五步,模拟数据丢失,进入MySQL,删除数据库
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[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
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第六步,导入数据
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[root@serv01 databackup]# mysql -uroot -p123456 <larrydb.sql
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第七步,登录MySQL,查看数据是否正常
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[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)
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对多个库进行备份
第一步,查看有哪些数据库
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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)
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第二步,备份多个库
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[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
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第三步,模拟数据丢失。
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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)
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第四步,恢复数据
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[root@serv01 databackup]# mysql -uroot -p123456 < larrydb_game.sql
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第五步,查看数据是否正常
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[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)
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备份所有的库
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[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
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备份某张表或者某几张表
第一步,备份某张表和某几张表
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[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
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第二步,模拟数据丢失
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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)
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第三步,查看数据是否正常
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[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 |
+ -----+---------+----------+
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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!!!
相信今天所学的知识在之后的学习工作中对大家有所帮助。