MySQL 备份和恢复（三）Xtrabackup实现热备：完全备份+增量备份

Percona XtraBackup is the world’s only open-source, free MySQL hot backup software that performs non-blocking backups for InnoDB and XtraDB databases. With Percona XtraBackup, you can achieve the following benefits:

Backups that complete quickly and reliably

Uninterrupted transaction processing during backups

Savings on disk space and network bandwidth

Automatic backup verification

Higher uptime due to faster restore time

以上摘自官方文档对Xtrabackup的描述。

Xtrabackup是Percona公司的开源mysql热备软件，软件自身支持完全备份和增量备份，功能强大，使用简单，且备份结束会自动检查备份的可用性。对于InnoDB和XtraDB可以实现无阻塞的备份。

Xtrabackup会在备份目录下自动生成以当前日期和时间为名的目录，目录下包含当前备份所有数据文件和丰富的当前备份时的状态信息。

实例演示：

xtrabackup的安装，安装包可从官网下载http://www.percona.com/software/percona-xtrabackup，官方提供了二进制和源码包，根据自己需要下载

/* 下载官方的rpm包安装，xtrabackup要依赖perl-DBD-mysql包，不想手动解决依赖关系可以yum localinstall安装 */

[root@console ~]# yum localinstall --nogpgcheck percona-xtrabackup-2.1.4-656.rhel6.x86_64.rpm -y

/* xtrabackup安装后生成的文件不多 */

[root@console ~]# rpm -ql percona-xtrabackup

/usr/bin/innobackupex        /* 备份时用的命令,会根据mysql版本自动调用xtrabackup_{55,56} */

/usr/bin/innobackupex-1.5.1     

/usr/bin/xbcrypt        /* 提供备份过程加密支持 */

/usr/bin/xbstream        /* 支持流式备份 */

/usr/bin/xtrabackup

/usr/bin/xtrabackup_55    / * 这个和下面那个才是备份过程实际调用的备份程序 */

/usr/bin/xtrabackup_56

/usr/share/doc/percona-xtrabackup-2.1.4

/usr/share/doc/percona-xtrabackup-2.1.4/COPYING    /* 文档只有一个软件授权文件，没有man文档，不过--help给出的帮助信息也比较丰富 */

备份过程：

/* 在库db1中准备一张表tb1，做效果比较用 */

MariaDB [(none)]> CREATE DATABASE db1;

Query OK, 1 row affected (0.00 sec)

MariaDB [(none)]> USE db1

Database changed

MariaDB [db1]> CREATE TABLE `tb1` (   `id` int(11) NOT NULL AUTO_INCREMENT,   `Name` varchar(30) NOT NULL,   `Gender` enum('F','M','O') NOT NULL,   PRIMARY KEY (`id`) );

Query OK, 0 rows affected (0.22 sec)

MariaDB [db1]> DESC tb1;

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

| Field  | Type              | Null | Key | Default | Extra          |

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

| id     | int(11)           | NO   | PRI | NULL    | auto_increment |

| Name   | varchar(30)       | NO   |     | NULL    |                |

| Gender | enum('F','M','O') | NO   |     | NULL    |                |

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

3 rows in set (0.00 sec)

MariaDB [db1]> INSERT INTO tb1 (Name,Gender) VALUES ('Tom','M'),('Jerry','F');

Query OK, 2 rows affected (0.05 sec)

Records: 2  Duplicates: 0  Warnings: 0

MariaDB [db1]> SELECT * FROM tb1;

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

| id | Name  | Gender |

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

|  1 | Tom   | M      |

|  2 | Jerry | F      |

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

2 rows in set (0.00 sec)

/* 创建一个用于备份的最小权限的用户 */

MariaDB [(none)]> CREATE USER 'bakuser'@'localhost' IDENTIFIED BY 'backupass';

Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> REVOKE ALL PRIVILEGES,GRANT OPTION FROM 'bakuser'@'localhost';

Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> GRANT RELOAD,LOCK TABLES,REPLICATION CLIENT ON *.* TO 'bakuser'@'localhost';

Query OK, 0 rows affected (0.00 sec)

现在先做一次完全备份：

/* 全备只需指定用于备份的用户名、密码和备份路径即可，最后出现innobackupex: completed OK! 则代表备份成功 */

[root@node1 ~]# innobackupex --user=bakuser --password=backupass /innobackup/

innobackupex: Backup created in directory '/innobackup/2014-07-31_09-27-36'

innobackupex: MySQL binlog position: filename 'mysql-bin.000001', position 1270

140731 09:27:39  innobackupex: Connection to database server closed

140731 09:27:40  innobackupex: completed OK!

/* 看一下备份都生成了哪些文件,除了数据库文件外还多了一些文件，注意由于我用root登陆系统，备份后的文件属主属组都是root，恢复后要改为运行mysqld进程的用户，不然mysql起不来 */

[root@node1 ~]# cd /innobackup/2014-07-31_09-27-36/

[root@node1 2014-07-31_09-27-36]# ll

total 18476

-rw-r--r--. 1 root root      260 Jul 31 09:27 backup-my.cnf /* 备份命令用到的配置选项信息 */

drwx------. 2 root root     4096 Jul 31 09:27 db1    

drwx------. 2 root root     4096 Jul 31 09:27 hellodb

-rw-r-----. 1 root root 18874368 Jul 31 09:27 ibdata1

drwx------. 2 root root     4096 Jul 31 09:27 mydb

drwxr-xr-x. 2 root root     4096 Jul 31 09:27 mysql

drwxr-xr-x. 2 root root     4096 Jul 31 09:27 performance_schema

drwxr-xr-x. 2 root root     4096 Jul 31 09:27 test

-rw-r--r--. 1 root root       13 Jul 31 09:27 xtrabackup_binary    /* 记录备份过程实际用的备份程序 */

-rw-r--r--. 1 root root       24 Jul 31 09:27 xtrabackup_binlog_info    /* 记录备份时的二进制日志文件和当前的位置 */

-rw-r-----. 1 root root       89 Jul 31 09:27 xtrabackup_checkpoints    /* 记录备份类型、

状态（是否prepared)、是否压缩、备份的LSN(Log Sequence Number日志序列号）范围等信息 */

-rw-r-----. 1 root root     2560 Jul 31 09:27 xtrabackup_logfile    /* xtrabackup自己的日志文件，新版本中不直接可见 */

[root@node1 2014-07-31_09-27-36]# cat backup-my.cnf 

# This MySQL options file was generated by innobackupex.

# The MySQL server

[mysqld]

innodb_data_file_path=ibdata1:10M:autoextend

innodb_log_files_in_group=2

innodb_log_file_size=5242880

innodb_fast_checksum=0

innodb_page_size=16384

innodb_log_block_size=512

[root@node1 2014-07-31_09-27-36]# cat xtrabackup_binary 

xtrabackup_55[root@node1 2014-07-31_09-27-36]# 

[root@node1 2014-07-31_09-27-36]# cat xtrabackup_binlog_info 

mysql-bin.000001    1270        

[root@node1 2014-07-31_09-27-36]# cat xtrabackup_checkpoints 

backup_type = full-backuped

from_lsn = 0

to_lsn = 1660869

last_lsn = 1660869

compact = 0

[root@node1 2014-07-31_09-27-36]# file xtrabackup_logfile 

xtrabackup_logfile: data

全备完成后，对数据库做一些修改后再做一次增备：

/* 第一次增量备份,--incremental 备份类型为增量， --incremental-basedir 指定这次增备是相对哪一个备份做的增量,这里是相对全备  */

[root@node1 innobackup]# innobackupex --user=bakuser --password=backupass --incremental /innobackup/ --incremental-basedir=/innobackup/2014-07-31_09-27-36/

innobackupex: Backup created in directory '/innobackup/2014-07-31_11-51-19'

innobackupex: MySQL binlog position: filename 'mysql-bin.000001', position 1525

140731 11:51:48  innobackupex: Connection to database server closed

140731 11:51:48  innobackupex: completed OK!

/* 做些修改，做第二次增备 */

MariaDB [db1]> DELETE FROM tb1 WHERE Name='Tom';

Query OK, 1 row affected (0.09 sec)

MariaDB [db1]> UPDATE tb1 SET Gender='F' WHERE Name='Dongfang Bubai';

Query OK, 1 row affected (0.02 sec)

Rows matched: 1  Changed: 1  Warnings: 0

MariaDB [db1]> SELECT * FROM tb1;

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

| id | Name           | Gender |

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

|  2 | Jerry          | F      |

|  3 | Bob            | M      |

|  4 | Dongfang Bubai | F      |

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

3 rows in set (0.00 sec)

/* incremental-basedir 相对第一次增量的增量 */

[root@node1 innobackup]# innobackupex --user=bakuser --password=backupass --incremental /innobackup/ --incremental-basedir=/innobackup/2014-07-31_11-51-19/

innobackupex: Backup created in directory '/innobackup/2014-07-31_11-59-29'

innobackupex: MySQL binlog position: filename 'mysql-bin.000001', position 1922

140731 11:59:33  innobackupex: Connection to database server closed

140731 11:59:33  innobackupex: completed OK!

/* 第二次增备完成后，再做一些数据修改操作，以模拟实际生产环境数据库突然崩溃场景 */

MariaDB [db1]> INSERT INTO tb1 (Name,Gender) VALUES ('Kangshifu Guamian','O');

Query OK, 1 row affected (0.04 sec)

/* 将二进制日志备份出来一份，生产环境中二进制日志切记不要和数据文件放在一起，

最好不要在同一分区甚至同一物理磁盘, 以免一旦玉石俱焚，悔之晚矣 */

[root@node1 innobackup]# mysql -e 'SHOW MASTER STATUS;'

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

| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |

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

| mysql-bin.000001 |     2168 |              |                  |

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

[root@node1 innobackup]# cp /mydata/data/

aria_log.00000001   hellodb/            ib_logfile1         mysql-bin.000001    node1.bob.org.pid

aria_log_control    ibdata1             mydb/               mysql-bin.index     performance_schema/

db1/                ib_logfile0         mysql/              node1.bob.org.err   test/

[root@node1 innobackup]# cp /mydata/data/mysql-bin.000001 /innobackup/

/* 人工让数据库彻底崩盘 */

[root@node1 innobackup]# service mysqld stop

Shutting down MySQL..                                      [  OK  ]

[root@node1 innobackup]# rm -rf /mydata/data/*

恢复：

    xtrabackup的恢复比较特殊，恢复前要先执行prepare过程，prepare主要完成把已提交的事务数据同步到数据文件，未完成的事务则回滚，这是对于只有一个完全备份来说。当还需要结合其他的增备时，则在些过程只需要将已提交的事务同步，未提交的事务则不用回滚，因为在本次备份时未提交的事务可能会在下一备份中已经提交，以避免这种无谓的劳动。

/* 注意 backup_type 和 to_lsn的变化 */

[root@node1 innobackup]# cat 2014-07-31_09-27-36/xtrabackup_checkpoints 

backup_type = full-backuped

from_lsn = 0

to_lsn = 1660869

last_lsn = 1660869

compact = 0 

/* Prepare全备,--apply-log 指定要prepare, --redo-only 只处理已提交事务，未提交的事务则不回滚

 backup_type由full-backuped --> full-prepared */

[root@node1 innobackup]# innobackupex --apply-log --redo-only /innobackup/2014-07-31_09-27-36/

...

140731 15:05:53  innobackupex: completed OK!

[root@node1 innobackup]# cat 2014-07-31_09-27-36/xtrabackup_checkpoints 

backup_type = full-prepared

from_lsn = 0

to_lsn = 1660869

last_lsn = 1660869

compact = 0

/* prepare 增备1， --incremental-dir 增备的路径 */

[root@node1 innobackup]# innobackupex --apply-log --redo-only /innobackup/2014-07-31_09-27-36/ --incremental-dir /innobackup/2014-07-31_11-51-19/

/* 再来看full backup 的 to_lsn 已经 --> 增备1 的 to_lsn了，此时增量1也就退出舞台了 */

[root@node1 innobackup]# cat 2014-07-31_11-51-19/xtrabackup_checkpoints 

backup_type = incremental

from_lsn = 1660869

to_lsn = 1661993

last_lsn = 1661993

compact = 0

[root@node1 innobackup]# cat 2014-07-31_09-27-36/xtrabackup_checkpoints 

backup_type = full-prepared

from_lsn = 0

to_lsn = 1661993

last_lsn = 1661993

compact = 0

/* prepare 增备2，增量1已经prepare上去了，所以基准还是全备，--incremental-dir 指向增量2 */

[root@node1 innobackup]# innobackupex --apply-log /innobackup/2014-07-31_09-27-36/ --incremental-dir=/innobackup/2014-07-31_11-59-29/

/* 完事后再瞅一眼，全备的 to_lsn 已经 --> 增量2 的了 */

[root@node1 innobackup]# cat 2014-07-31_09-27-36/xtrabackup_checkpoints 

backup_type = full-prepared

from_lsn = 0

to_lsn = 1664255

last_lsn = 1664255

compact = 0

[root@node1 innobackup]# cat 2014-07-31_11-59-29/xtrabackup_checkpoints 

backup_type = incremental

from_lsn = 1661993

to_lsn = 1664255

last_lsn = 1664255

compact = 0

至此，恢复的预准备工作已完成，两个增备也完成了历史使命，恢复只要用全备的一个就可以了：

/* 恢复过程灰常简单，恢复过程也不需要启动mysql, 但是备份过程是一定要启动mysql的，因为要以备份用户身份连到Mysql上的嘛 */

[root@node1 innobackup]# innobackupex --copy-back /innobackup/2014-07-31_09-27-36/

/* 现在还不能启动mysql, 对了，属主属组还没改 */

[root@node1 innobackup]# ll /mydata/data/

total 18456

drwxr-xr-x. 2 root root     4096 Jul 31 15:54 db1

drwxr-xr-x. 2 root root     4096 Jul 31 15:54 hellodb

-rw-r--r--. 1 root root 18874368 Jul 31 15:54 ibdata1

drwxr-xr-x. 2 root root     4096 Jul 31 15:54 mydb

drwxr-xr-x. 2 root root     4096 Jul 31 15:54 mysql

drwxr-xr-x. 2 root root     4096 Jul 31 15:54 performance_schema

drwxr-xr-x. 2 root root     4096 Jul 31 15:54 test

[root@node1 innobackup]# chown -R mysql.mysql /mydata/data/*

/* 现在就可以启动了 。。 */

[root@node1 innobackup]# service mysqld start

Starting MySQL.....                                        [  OK  ]

/* 正常启动，数据都在 */

MariaDB [db1]> SELECT * FROM tb1;

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

| id | Name           | Gender |

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

|  2 | Jerry          | F      |

|  3 | Bob            | M      |

|  4 | Dongfang Bubai | F      |

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

3 rows in set (0.00 sec)

再加上最后的二进制日志恢复，整个恢复过程就全搞颠了

[root@node1 innobackup]# cat /innobackup/2014-07-31_11-59-29/xtrabackup_binlog_info 

mysql-bin.000001    1922        

[root@node1 innobackup]# mysqlbinlog --start-position=1922 mysql-bin.000001 > 11.sql

[root@node1 innobackup]# mysql < 11.sql 

MariaDB [(none)]> SELECT * FROM db1.tb1;

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

| id | Name              | Gender |

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

|  2 | Jerry             | F      |

|  3 | Bob               | M      |

|  4 | Dongfang Bubai    | F      |

|  5 | Kangshifu Guamian | O      |

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

4 rows in set (0.01 sec)

/* 二进制日志恢复，kangshifu guamian finnaly O 出锅了 */

To be continued ...

©著作权归作者所有：来自51CTO博客作者googleluck的原创作品，如需转载，请注明出处，否则将追究法律责任

mysql innodbxtrabackup 数据库