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 */
# 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 */
# 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 > 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 > 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 > INSERT INTO tb1 (Name,Gender) VALUES ('Tom','M'),('Jerry','F');
Query OK, 2 rows affected (0.05 sec)
Records: 2Duplicates: 0Warnings: 0
MariaDB > 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 */
# 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 09:27:39innobackupex: Connection to database server closed
140731 09:27:40innobackupex: 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 */
# cd /innobackup/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 */
# cat backup-my.cnf
# This MySQL options file was generated by innobackupex.
# The MySQL server
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
# cat xtrabackup_binary
xtrabackup_55#
# cat xtrabackup_binlog_info
mysql-bin.0000011270
# cat xtrabackup_checkpoints
backup_type = full-backuped
from_lsn = 0
to_lsn = 1660869
last_lsn = 1660869
compact = 0
# 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*/
# 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 11:51:48innobackupex: Connection to database server closed
140731 11:51:48innobackupex: completed OK!
/* 做些修改，做第二次增备 */
MariaDB > DELETE FROM tb1 WHERE Name='Tom';
Query OK, 1 row affected (0.09 sec)
MariaDB > UPDATE tb1 SET Gender='F' WHERE Name='Dongfang Bubai';
Query OK, 1 row affected (0.02 sec)
Rows matched: 1Changed: 1Warnings: 0
MariaDB > 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 */
# 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 11:59:33innobackupex: Connection to database server closed
140731 11:59:33innobackupex: 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 > 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 */
# mysql -e 'SHOW MASTER STATUS;'
+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000001 | 2168 | | |
+------------------+----------+--------------+------------------+
# 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/
# cp /mydata/data/mysql-bin.000001 /innobackup/
/* 人工让数据库彻底崩盘 */
# service mysqld stop
Shutting down MySQL..
# 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 */
# 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 */
# innobackupex --apply-log --redo-only /innobackup/2014-07-31_09-27-36/
...
140731 15:05:53innobackupex: completed OK!
# 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 */
# 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 */
# cat 2014-07-31_11-51-19/xtrabackup_checkpoints
backup_type = incremental
from_lsn = 1660869
to_lsn = 1661993
last_lsn = 1661993
compact = 0
# 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 */
# 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 */
# cat 2014-07-31_09-27-36/xtrabackup_checkpoints
backup_type = full-prepared
from_lsn = 0
to_lsn = 1664255
last_lsn = 1664255
compact = 0
# 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 */
# 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 */
# 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
# chown -R mysql.mysql /mydata/data/*
/* 现在就可以启动了 。。 */
# service mysqld start
Starting MySQL.....
/* 正常启动，数据都在 */
MariaDB > 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
# cat /innobackup/2014-07-31_11-59-29/xtrabackup_binlog_info
mysql-bin.0000011922
# mysqlbinlog --start-position=1922 mysql-bin.000001 > 11.sql
# 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 ...
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