MySQL innodb引擎备份工具XtraBackup之二（数据库全备）

MySQL innodb引擎备份工具XtraBackup之二（数据库全备）

Xtrabackup备份原理：

在InnoDB内部会维护一个redo日志文件，我们也可以叫做事务日志文件。事务日志会存储每一个InnoDB表数据的记录修改。当InnoDB启动时，InnoDB会检查数据文件和事务日志，并执行两个步骤：它应用(前滚)已经提交的事务日志到数据文件，并将修改过但没有提交的数据进行回滚操作。

xtrabackup在启动时会记住log sequence number(LSN)，并且复制所有的数据文件。复制过程需要一些时间，所以这期间如果数据文件有改动，那么将会使数据库处于一个不同的时间点。这时，xtrabackup会运行一个后台进程，用于监视事务日志，并从事务日志复制***的修改。xtrabackup必须持续的做这个操作，是因为事务日志是会轮转重复的写入，并且事务日志可以被重用。所以xtrabackup自启动开始，就不停的将事务日志中每个数据文件的修改都记录下来。

上面就是xtrabackup的备份过程。接下来是准备(prepare)过程。在这个过程中，xtrabackup使用之前复制的事务日志，对各个数据文件执行灾难恢复(就像MySQL刚启动时要做的一样)。当这个过程结束后，数据库就可以做恢复还原了。

以上的过程在xtrabackup的编译二进制程序中实现。程序innobackupex可以允许我们备份MyISAM表和frm文件从而增加了便捷和功能。Innobackupex会启动xtrabackup，直到xtrabackup复制数据文件后，然后执行FLUSH TABLES WITH READ LOCK来阻止新的写入进来并把MyISAM表数据刷到硬盘上，之后复制MyISAM数据文件，***释放锁。

备份MyISAM和InnoDB表最终会处于一致，在准备(prepare)过程结束后，InnoDB表数据已经前滚到整个备份结束的点，而不是回滚到xtrabackup刚开始时的点。这个时间点与执行FLUSH TABLES WITH READ LOCK的时间点相同，所以MyISAM表数据与InnoDB表数据是同步的。类似***的，InnoDB的prepare过程可以称为recover(恢复)，MyISAM的数据复制过程可以称为restore(还原)。

xtrabackup和innobackupex这两个工具都提供了许多前文没有提到的功能特点。手册上有对各个功能都有详细的介绍。简单介绍下，这些工具提供了如流(streaming)备份，增量(incremental)备份等，通过复制数据文件，复制日志文件和提交日志到数据文件(前滚)实现了各种复合备份方式。

如下图所示：

案例分析：

一、数据库全备

1、创建配置文件

[root@rh64 ~]# cat /tmp/my.cnf

[mysqld]

datadir=/var/lib/mysql

socket=/var/lib/mysql/mysql.sock

user=mysql

symbolic-links=0

innodb_data_file_path=ibdata1:12M;ibdata2:10M:autoextend

innodb_log_files_in_group=2

innodb_log_file_size=50331648

2、创建备份目录

[root@rh64 ~]# ls -ld /data/mysql/backup/

drwxrwxrwx. 3 mysql mysql 4096 Oct 15 12:13 /data/mysql/backup/

3、测试

mysql> show databases;

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

| Database |

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

| information_schema |

| mysql |

| performance_schema |

| prod |

| test |

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

5 rows in set (0.06 sec)

mysql> use prod;

You can turn off this feature to get a quicker startup with -A

Database changed

mysql> show tables;

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

| Tables_in_prod |

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

| t1 |

| t2 |

| t3 |

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

3 rows in set (0.00 sec)

mysql> select count(*) from t1;

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

| count(*) |

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

| 49152 |

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

1 row in set (0.13 sec)

插入数据：

mysql> insert into t1 select * from t1;

Query OK, 49152 rows affected (0.69 sec)

Records: 49152 Duplicates: 0 Warnings: 0

Query OK, 0 rows affected (0.00 sec)

mysql> select count(*) from t1;

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

| count(*) |

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

| 98304 |

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

1 row in set (0.03 sec)

4、创建备份用户并授权

mysql> create user 'bkusr'@'%' identified by '***';

Query OK, 0 rows affected (0.00 sec)

mysql> grant reload,create tablespace,lock tables ,replication client,super on *.* to 'bakusr'@'%';

Query OK, 0 rows affected (0.00 sec

mysql> create user 'bakusr'@localhost identified by '***';

Query OK, 0 rows affected (0.00 sec)

5、进行数据库全备

[root@rh64 ~]# innobackupex --user=bakusr --password='***' --socket=/var/lib/mysql/mysql.sock --defaults-file=/tmp/my.cnf /data/mysql/backup/full

----提示配置文件参数必须放在***位

以root用户备份：

[root@rh64 ~]# innobackupex --defaults-file=/etc/my.cnf --user=root --password='***' --socket=/var/lib/mysql/mysql.sock /data/mysql/backup/full

查看备份：

[root@rh64 backup]# ls

bak.sh full prod t.txt

[root@rh64 backup]# cd full

[root@rh64 full]# ls

2015-10-28_14-23-23

[root@rh64 full]# cd 2015-10-28_14-23-23/

[root@rh64 2015-10-28_14-23-23]# ls -lt

total 22560

-rw-r----- 1 root root 507 Oct 28 14:23 xtrabackup_info

-rw-r----- 1 root root 398 Oct 28 14:23 backup-my.cnf

-rw-r----- 1 root root 115 Oct 28 14:23 xtrabackup_checkpoints

-rw-r----- 1 root root 2560 Oct 28 14:23 xtrabackup_logfile

drwx------ 2 root root 4096 Oct 28 14:23 performance_schema

drwx------ 2 root root 4096 Oct 28 14:23 mysql

drwx------ 2 root root 4096 Oct 28 14:23 test

drwx------ 2 root root 4096 Oct 28 14:23 prod

-rw-r----- 1 root root 10485760 Oct 28 14:23 ibdata2

-rw-r----- 1 root root 12582912 Oct 28 14:23 ibdata1

[root@rh64 2015-10-28_14-23-23]#

使用参数：--no-timestamp

[root@rh64 backup]# innobackupex --defaults-file=/etc/my.cnf --user=root --password='***' --socket=/var/lib/mysql/mysql.sock /data/mysql/backup/full --no-timestamp

则不建立时间相关的目录：

[root@rh64 backup]# ls

bak.sh full prod t.txt

[root@rh64 backup]# cd full

[root@rh64 full]# ls

backup-my.cnf ibdata2 performance_schema test xtrabackup_info

ibdata1 mysql prod xtrabackup_checkpoints xtrabackup_logfile

[root@rh64 full]# ls -l

total 22560

-rw-r----- 1 root root 398 Oct 28 14:25 backup-my.cnf

-rw-r----- 1 root root 12582912 Oct 28 14:25 ibdata1

-rw-r----- 1 root root 10485760 Oct 28 14:25 ibdata2

drwx------ 2 root root 4096 Oct 28 14:25 mysql

drwx------ 2 root root 4096 Oct 28 14:25 performance_schema

drwx------ 2 root root 4096 Oct 28 14:25 prod

drwx------ 2 root root 4096 Oct 28 14:25 test

-rw-r----- 1 root root 115 Oct 28 14:25 xtrabackup_checkpoints

-rw-r----- 1 root root 522 Oct 28 14:25 xtrabackup_info

-rw-r----- 1 root root 2560 Oct 28 14:25 xtrabackup_logfile

使用普通用户备份：

[root@rh64 ~]# innobackupex --defaults-file=/etc/my.cnf --user=bakusr --password='***' --socket=/var/lib/mysql/mysql.sock /data/mysql/backup/full

Error: failed to execute query LOCK TABLES FOR BACKUP: Access denied; you need (at least one of) the RELOAD privilege(s) for this operation

----提示：缺少reload权限

查看用户权限：

mysql> select user,host,Reload_priv from user where user='bakusr';

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

| user | host | Reload_priv |

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

| bakusr | % | Y |

| bakusr | localhost | N |

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

2 rows in set (0.04 sec)

授权：

mysql> grant reload,create tablespace,lock tables ,replication client,super on *.* to 'bakusr'@localhost;

Query OK, 0 rows affected (0.08 sec)

mysql> select user,host,Reload_priv from user where user='bakusr';

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

| user | host | Reload_priv |

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

| bakusr | % | Y |

| bakusr | localhost | Y |

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

2 rows in set (0.15 sec)

备份：

[root@rh64 ~]# innobackupex --defaults-file=/etc/my.cnf --user=bakusr --password='***' --socket=/var/lib/mysql/mysql.sock /data/mysql/backup/full --no-timestamp

[root@rh64 backup]# ls -l full

total 22560

-rw-r----- 1 root root 398 Oct 28 14:35 backup-my.cnf

-rw-r----- 1 root root 12582912 Oct 28 14:35 ibdata1

-rw-r----- 1 root root 10485760 Oct 28 14:35 ibdata2

drwx------ 2 root root 4096 Oct 28 14:35 mysql

drwx------ 2 root root 4096 Oct 28 14:35 performance_schema

drwx------ 2 root root 4096 Oct 28 14:35 prod

drwx------ 2 root root 4096 Oct 28 14:35 test

-rw-r----- 1 root root 115 Oct 28 14:35 xtrabackup_checkpoints

-rw-r----- 1 root root 524 Oct 28 14:35 xtrabackup_info

-rw-r----- 1 root root 2560 Oct 28 14:35 xtrabackup_logfile

二、数据库恢复

1、测试

关闭数据库，更改datadir目录

[mysql@rh64 ~]$ service mysql stop

Shutting down MySQL (Percona Server)...[ OK ]

rm: cannot remove `/var/lock/subsys/mysql': Permission denied

[root@rh64 ~]# mv /var/lib/mysql /var/lib/mysql.bak

[root@rh64 ~]# cd /var/lib/mysql.bak

[root@rh64 mysql.bak]# ls

auto.cnf ibdata2 ib_logfile1 mysql prod RPM_UPGRADE_HISTORY test

ibdata1 ib_logfile0 ib_logfile101 performance_schema rh64.pid RPM_UPGRADE_MARKER-LAST

创建新的datadir:

[root@rh64 mysql.bak]# mkdir /var/lib/mysql

数据库恢复：

[root@rh64 backup]# innobackupex --defaults-file=/etc/my.cnf --copy-back --rsync /data/mysql/backup/full

......

151028 14:35:22 [01] Copying ./performance_schema/events_waits_history.frm to /data/mysql/backup/full/performance_schema/events_waits_history.frm

151028 14:35:22 [01] ...done

151028 14:35:22 [01] Copying ./performance_schema/host_cache.frm to /data/mysql/backup/full/performance_schema/host_cache.frm

151028 14:35:22 [01] ...done

151028 14:35:22 [01] Copying ./performance

......

151028 14:41:53 [01] ...done

151028 14:41:53 [01] Copying ./performance_schema/events_stages_history_long.frm to /var/lib/mysql/performance_schema/events_stages_history_long.frm

151028 14:41:53 [01] ...done

151028 14:41:53 [01] Copying ./xtrabackup_info to /var/lib/mysql/xtrabackup_info

151028 14:41:53 [01] ...done

重新授权datadir：

[root@rh64 lib]# ls -ld mysql.bak/

drwxr-xr-x. 6 mysql mysql 4096 Oct 28 14:38 mysql.bak/

[root@rh64 lib]# ls -ld mysql

drwxr-xr-x 6 root root 4096 Oct 28 14:45 mysql

[root@rh64 lib]# ls -l mysql.bak/

total 170020

-rw-rw----. 1 mysql mysql 56 Sep 6 18:08 auto.cnf

-rw-rw----. 1 mysql mysql 12582912 Oct 28 14:38 ibdata1

-rw-rw----. 1 mysql mysql 10485760 Oct 28 14:38 ibdata2

-rw-rw----. 1 mysql mysql 50331648 Oct 28 14:38 ib_logfile0

-rw-rw----. 1 mysql mysql 50331648 Sep 6 18:06 ib_logfile1

-rw-rw----. 1 mysql mysql 50331648 Sep 11 11:50 ib_logfile101

drwx------. 2 mysql mysql 4096 Sep 6 18:06 mysql

drwx------. 2 mysql mysql 4096 Sep 6 18:06 performance_schema

drwx------. 2 mysql mysql 4096 Oct 13 16:41 prod

-rw-rw----. 1 mysql mysql 5 Oct 15 11:36 rh64.pid

-rw-r--r--. 1 root root 293 Sep 6 18:07 RPM_UPGRADE_HISTORY

-rw-r--r--. 1 mysql mysql 293 Sep 6 18:07 RPM_UPGRADE_MARKER-LAST

drwx------. 2 mysql mysql 4096 Sep 6 18:06 test

[root@rh64 lib]# chown -R mysql.mysql mysql

验证数据恢复：

[root@rh64 lib]# service mysql start

Starting MySQL (Percona Server)....[ OK ]

[root@rh64 lib]# mysql -u root -p

Enter password:

Your MySQL connection id is 1

Server version: 5.6.25-73.1 Percona Server (GPL), Release 73.1, Revision 07b797f

Copyright (c) 2009-2015 Percona LLC and/or its affiliates

Copyright (c) 2000, 2015, *** and/or its affiliates. All rights reserved.

*** is a registered trademark of *** 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>

mysql> use prod;

You can turn off this feature to get a quicker startup with -A

Database changed

mysql> select count(*) from t1;

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

| count(*) |

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

| 98304 |

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

1 row in set (0.04 sec)

---至此，数据恢复成功!!!

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