mysql用Xtrabackup全备和增量备份(一)

一个合格的运维工程师或者dba工程师，如果有从事数据库方面的话，首先需要做的就是备份，如果没有备份，出现问题的话，你的业务就会出问题，你的工作甚至会。。。

所以备份是重要的，但光有备份还不行，备份后如果出现问题，你还得使用备份数据来恢复，但恢复数据的时间一般都是很长的，不符合业务需求，所以一个快速备份与恢复的软件就很有必要。

之前我在维护mysql数据库的时候，使用mysqldump来进行备份与恢复，在备份的时候锁住表，然后全部备份，在数据少的时候没问题，但如果数据很多，不允许锁表，同时需要恢复数据块的情况，mysqldump就不适合了，我在恢复一个4G数据文件的数据库的时候，恢复的数据是使用mysqldump的数据，恢复了3个小时还没有反应，造成的影响很严重，所以我开始寻找其他的别发软件来满足以上的需求，幸好找到了，就是使用xtrabackup来进行备份与恢复，恢复4G数据文件的数据库，仅需要14秒，同时在备份的时候不会锁表，而且支持增量备份，所以把我的比较分享给大家，希望对大家有益！

Xtrabackup 是percona公司的开源项目，用以实现类似innodb官方的热备份工具InnoDB Hot Backup的功能，能够非常快速地备份与恢复mysql数据库。 Xtrabackup中包含两个工具：

xtrabackup是用于热备份innodb, xtradb表中数据的工具，不能备份其他类型的表，也不能备份数据表结构；

innobackupex是将xtrabackup进行封装的perl脚本，提供了备份myisam表的能力。

由于innobackupex的功能更为全面和完善，所以，本文以innobackupex作为基础进行研究描述。

下面介绍xtrabackup的全部、增量的备份与恢复。

一、下载与安装

1、下载

wget http://www.percona.com/redir/downloads/XtraBackup/XtraBackup-1.6.7/binary/Linux/x86_64/xtrabackup-1.6.7.tar.gz

2、安装依赖库

如果是debian系列的话

apt-get install debhelper autotools-dev libaio-dev wget automake   libtool bison libncurses-dev libz-dev cmake bzr

如果是redhat系列的话

yum install cmake gcc gcc-c++ libaio libaio-devel automake autoconf bzr   bison libtool ncurses-devel zlib-devel

3、解压

tar zxvf xtrabackup-1.6.7.tar.gz

4、进入目录

cd xtrabackup-1.6.7

5、复制

cd bin
cp * /usr/bin
然后就安装完成了，下面开始备份

其中，

innobackupex是我们要使用的备份工具；

xtrabackup是被封装在innobackupex之中的，innobackupex运行时需要调用它；

xtrabackup_51是xtrabackup运行时需要调用的工具；

tar4ibd是以tar流的形式产生备份时用来打包的工具。

6、对某个数据库进行全部备份的命令介绍

innobackupex --user=root--password=123456--defaults-file=/etc/mysql/my.cnf --database=test--stream=tar /tmp/data/ 2>/tmp/data/err.log|gzip 1>/tmp/data/test.tar.gz

说明：
     --database=test 单独对test数据库做备份 ，若是不添加此参数那就那就是对全库做备份
     2>/tmp/data/err.log 输出信息写入日志中
     1>/tmp/data/test.tar.gz 打包压缩存储到该文件中

二、对数据库的全部备份与恢复

下面开始测试xtrabackup的全部备份

（1）先进入mysql里创建一个新的test数据库

root@client2:/tmp# mysql -u root -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 40
Server version: 5.5.28-0ubuntu0.12.04.3-log (Ubuntu)

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> drop database test;
Query OK, 3 rows affected (0.13 sec)
mysql> create database test;
Query OK, 1 row affected (0.00 sec)

mysql> use test;
Database changed
mysql> create table test (id int);
Query OK, 0 rows affected (0.06 sec)
mysql> insert into test values(1);
Query OK, 1 row affected (0.04 sec)

mysql> insert into test values(2);
Query OK, 1 row affected (0.01 sec)

mysql> insert into test values(3);
Query OK, 1 row affected (0.00 sec)

mysql> insert into test values(4);
Query OK, 1 row affected (0.00 sec)

mysql> insert into test values(5);
Query OK, 1 row affected (0.01 sec)

mysql> select * from test;
+------+
| id   |
+------+
|    1 |
|    2 |
|    3 |
|    4 |
|    5 |
+------+
5 rows in set (0.00 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

（2）然后备份test的整个数据库

使用下面的backup.sh脚本

root@client2:/tmp# cat backup.sh
#!/bin/bash
user='root'
passwd='123456'
database=test
my_config='/etc/mysql/my.cnf'
log=$database-$(date +%Y%m%d%H%M).log
str=$database-$(date +%Y%m%d%H%M).tar.gz
backup_dir='/tmp/data'
echo "Start to backup at $(date +%Y%m%d%H%M)"
if [ ! -d "$backup_dir" ];then
    mkdir $backup_dir
fi
innobackupex --user=$user --password=$passwd --defaults-file=$my_config --database=$database --stream=tar $backup_dir 2>$backup_dir/$log | gzip 1>$backup_dir/$str
if [ $? -eq 0 ];then
    echo "Backup is finish! at $(date +%Y%m%d%H%M)"
    exit 0
else
    echo "Backup is Fail! at $(date +%Y%m%d%H%M)"
    exit 1
fi

现在开始运行此脚本

root@client2:/tmp# sh backup.sh
Start to backup at 201303072101
Backup is finish! at 201303072102

然后到data里查看结果

root@client2:/tmp# cd data
root@client2:/tmp/data# ll
total 3272
drwxr-xr-x  2 root root    4096 Mar  7 21:01 ./
drwxrwxrwt 13 root root    4096 Mar  7 21:02 ../
-rw-r--r--  1 root root    3780 Mar  7 21:02 test-201303072101.log
-rw-r--r--  1 root root 3336909 Mar  7 21:02 test-201303072101.tar.gz
root@client2:/tmp/data# cat test-201303072101.log

InnoDB Backup Utility v1.5.1-xtrabackup; Copyright 2003, 2009 Innobase Oy
and Percona Inc 2009-2012.  All Rights Reserved.

This software is published under
the GNU GENERAL PUBLIC LICENSE Version 2, June 1991.

130307 21:01:39  innobackupex: Starting mysql with options:  --defaults-file='/etc/mysql/my.cnf'--password=xxxxxxxx--user='root' --unbuffered --
130307 21:01:39  innobackupex: Connected to database with mysql child process (pid=12441)
130307 21:01:45  innobackupex: Connection to database server closed
IMPORTANT: Please check that the backup run completes successfully.
           At the end of a successful backup run innobackupex
           prints "completed OK!".

innobackupex: Using mysql  Ver 14.14 Distrib 5.5.28, for debian-linux-gnu (x86_64) using readline 6.2
innobackupex: Using mysql server version Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.

innobackupex: Created backup directory /tmp/data
130307 21:01:45  innobackupex: Starting mysql with options:  --defaults-file='/etc/mysql/my.cnf'--password=xxxxxxxx--user='root' --unbuffered --
130307 21:01:45  innobackupex: Connected to database with mysql child process (pid=12471)
130307 21:01:47  innobackupex: Connection to database server closed

130307 21:01:47  innobackupex: Starting ibbackup with command: xtrabackup_55  --defaults-file="/etc/mysql/my.cnf" --backup --suspend-at-end --log-stream --target-dir=/tmp
innobackupex: Waiting for ibbackup (pid=12478) to suspend
innobackupex: Suspend file '/tmp/xtrabackup_suspended'

xtrabackup: suspend-at-end is enabled.
xtrabackup: uses posix_fadvise().
xtrabackup: cd to /var/lib/mysql
xtrabackup: Target instance is assumed as followings.
xtrabackup:   innodb_data_home_dir = ./
xtrabackup:   innodb_data_file_path = ibdata1:10M:autoextend
xtrabackup:   innodb_log_group_home_dir = ./
xtrabackup:   innodb_log_files_in_group = 2
xtrabackup:   innodb_log_file_size = 5242880
130307 21:01:47 InnoDB: Using Linux native AIO
xtrabackup: Stream mode.
>> log scanned up to (59605543)

130307 21:01:49  innobackupex: Continuing after ibbackup has suspended

innobackupex: Starting to backup InnoDB tables and indexes
innobackupex: from original InnoDB data directory '/var/lib/mysql'
innobackupex: Backing up as tar stream 'ibdata1'
130307 21:01:52  innobackupex: Starting mysql with options:  --defaults-file='/etc/mysql/my.cnf'--password=xxxxxxxx--user='root' --unbuffered --
130307 21:01:52  innobackupex: Connected to database with mysql child process (pid=12494)
>> log scanned up to (59605543)
130307 21:01:54  innobackupex: Starting to lock all tables...
>> log scanned up to (59605543)
>> log scanned up to (59605543)
130307 21:02:04  innobackupex: All tables locked and flushed to disk

130307 21:02:04  innobackupex: Starting to backup .frm, .MRG, .MYD, .MYI,
innobackupex: .TRG, .TRN, .ARM, .ARZ, .CSM, .CSV and .opt files in
innobackupex: subdirectories of '/var/lib/mysql'
innobackupex: Backing up file '/var/lib/mysql/test/test.frm'
innobackupex: Backing up file '/var/lib/mysql/test/db.opt'
130307 21:02:04  innobackupex: Finished backing up .frm, .MRG, .MYD, .MYI, .TRG, .TRN, .ARM, .ARZ, .CSV, .CSM and .opt files

innobackupex: Resuming ibbackup

xtrabackup: The latest check point (for incremental): '59605543'
>> log scanned up to (59605543)
xtrabackup: Transaction log of lsn (59605543) to (59605543) was copied.
130307 21:02:06  innobackupex: All tables unlocked
130307 21:02:06  innobackupex: Connection to database server closed

innobackupex: Backup created in directory '/tmp/data'
innobackupex: MySQL binlog position: filename 'mysql-bin.000022', position 107
innobackupex: You must use -i (--ignore-zeros) option for extraction of the tar stream.
130307 21:02:06  innobackupex: completed OK!

可以看到备份完成了

（3）恢复数据库

先关闭mysql服务，然后再删除test数据库文件

root@client2:/tmp/data# service mysql stop
mysql stop/waiting
root@client2:/tmp/data# cd /var/lib/mysql/
root@client2:/var/lib/mysql# ll
total 77860
drwx------  8 mysql mysql     4096 Mar  7 20:59 ./
drwxr-xr-x 38 root  root      4096 Mar  7 19:52 ../
-rw-r--r--  1 root  root         0 Jan  5 14:22 debian-5.5.flag
drwx------  2 mysql mysql     4096 Feb 11 17:39 django/
-rw-rw----  1 mysql mysql 69206016 Mar  7 21:02 ibdata1
-rw-rw----  1 mysql mysql  5242880 Mar  7 21:02 ib_logfile0
-rw-rw----  1 mysql mysql  5242880 Mar  7 21:01 ib_logfile1
drwx------  2 mysql mysql     4096 Jan  5 22:55 monitor/
drwx------  2 mysql root      4096 Jan  5 14:22 mysql/
-rw-rw----  1 root  root         6 Jan  5 14:22 mysql_upgrade_info
drwx------  2 mysql mysql     4096 Jan  5 14:22 performance_schema/
drwx------  2 mysql mysql     4096 Mar  7 21:00 test/
drwxr-xr-x  2 mysql mysql     4096 Mar  7 19:58 xtrbackup/
root@client2:/var/lib/mysql# rm -rf test
root@client2:/var/lib/mysql# ll
total 77856
drwx------  7 mysql mysql     4096 Mar  7 21:03 ./
drwxr-xr-x 38 root  root      4096 Mar  7 19:52 ../
-rw-r--r--  1 root  root         0 Jan  5 14:22 debian-5.5.flag
drwx------  2 mysql mysql     4096 Feb 11 17:39 django/
-rw-rw----  1 mysql mysql 69206016 Mar  7 21:02 ibdata1
-rw-rw----  1 mysql mysql  5242880 Mar  7 21:02 ib_logfile0
-rw-rw----  1 mysql mysql  5242880 Mar  7 21:01 ib_logfile1
drwx------  2 mysql mysql     4096 Jan  5 22:55 monitor/
drwx------  2 mysql root      4096 Jan  5 14:22 mysql/
-rw-rw----  1 root  root         6 Jan  5 14:22 mysql_upgrade_info
drwx------  2 mysql mysql     4096 Jan  5 14:22 performance_schema/
drwxr-xr-x  2 mysql mysql     4096 Mar  7 19:58 xtrbackup/

开始恢复数据库

先把之前/tmp/data里的数据库压缩版给解压

root@client2:cd /tmp/data
root@client2:/tmp/data# tar -izxvf test-201303072101.tar.gz -C /tmp/restore/
backup-my.cnf
ibdata1
xtrabackup_binlog_info
test/test.frm
test/db.opt
xtrabackup_logfile
xtrabackup_checkpoints
xtrabackup_binary

注意：这里tar解包必须使用-i参数，否则解压出来的文件只有一个backup-my.cnf

查看一下restore的内容

root@client2:/tmp/data# cd /tmp/restore/
root@client2:/tmp/restore# ll
total 67616
drwxr-xr-x  3 root  root      4096 Mar  7 21:03 ./
drwxrwxrwt 14 root  root      4096 Mar  7 21:03 ../
-rw-r--r--  1 root  root       260 Mar  7 21:01 backup-my.cnf
-rw-rw----  1 mysql mysql 69206016 Mar  7 21:01 ibdata1
drwxr-xr-x  2 root  root      4096 Mar  7 21:03 test/
-rw-r--r--  1 root  root        13 Mar  7 21:02 xtrabackup_binary
-rw-r--r--  1 root  root        23 Mar  7 21:02 xtrabackup_binlog_info
-rw-r--r--  1 root  root        79 Mar  7 21:02 xtrabackup_checkpoints
-rw-r--r--  1 root  root      2560 Mar  7 21:02 xtrabackup_logfile

然后将备份文件中的日志应用到备份文件中的数据文件上

root@client2:/tmp/restore# innobackupex --user=root--password=123456 --apply-log /tmp/restore/

InnoDB Backup Utility v1.5.1-xtrabackup; Copyright 2003, 2009 Innobase Oy
and Percona Inc 2009-2012.  All Rights Reserved.

This software is published under
the GNU GENERAL PUBLIC LICENSE Version 2, June 1991.

IMPORTANT: Please check that the apply-log run completes successfully.
           At the end of a successful apply-log run innobackupex
           prints "completed OK!".



130307 21:04:18  innobackupex: Starting ibbackup with command: xtrabackup_55  --defaults-file="/tmp/restore/backup-my.cnf" --prepare --target-dir=/tmp/restore

xtrabackup_55 version 1.6.7 for Percona Server 5.5.16 Linux (x86_64) (revision id: undefined)
xtrabackup: cd to /tmp/restore
xtrabackup: This target seems to be not prepared yet.
xtrabackup: xtrabackup_logfile detected: size=2097152, start_lsn=(59605543)
xtrabackup: Temporary instance for recovery is set as followings.
xtrabackup:   innodb_data_home_dir = ./
xtrabackup:   innodb_data_file_path = ibdata1:10M:autoextend
xtrabackup:   innodb_log_group_home_dir = ./
xtrabackup:   innodb_log_files_in_group = 1
xtrabackup:   innodb_log_file_size = 2097152
130307 21:04:19 InnoDB: Using Linux native AIO
xtrabackup: Starting InnoDB instance for recovery.
xtrabackup: Using 104857600 bytes for buffer pool (set by --use-memory parameter)
130307 21:04:19 InnoDB: The InnoDB memory heap is disabled
130307 21:04:19 InnoDB: Mutexes and rw_locks use GCC atomic builtins
130307 21:04:19 InnoDB: Compressed tables use zlib 1.2.3
130307 21:04:19 InnoDB: Using Linux native AIO
130307 21:04:19 InnoDB: Warning: innodb_file_io_threads is deprecated. Please use innodb_read_io_threads and innodb_write_io_threads instead
130307 21:04:19 InnoDB: Initializing buffer pool, size = 100.0M
130307 21:04:19 InnoDB: Completed initialization of buffer pool
130307 21:04:19 InnoDB: highest supported file format is Barracuda.
InnoDB: The log sequence number in ibdata files does not match
InnoDB: the log sequence number in the ib_logfiles!
130307 21:04:19  InnoDB: Database was not shut down normally!
InnoDB: Starting crash recovery.
InnoDB: Reading tablespace information from the .ibd files...
InnoDB: Last MySQL binlog file position 0 107, file name /var/log/mysql/mysql-bin.000022
130307 21:04:20  InnoDB: Waiting for the background threads to start
130307 21:04:21 Percona XtraDB (http://www.percona.com) 1.1.8-20.1 started; log sequence number 59605543

[notice (again)]
  If you use binary log and don't use any hack of group commit,
  the binary log position seems to be:
InnoDB: Last MySQL binlog file position 0 107, file name /var/log/mysql/mysql-bin.000022

xtrabackup: starting shutdown with innodb_fast_shutdown = 1
130307 21:04:21  InnoDB: Starting shutdown...
130307 21:04:25  InnoDB: Shutdown completed; log sequence number 59606758

130307 21:04:25  innobackupex: Restarting xtrabackup with command: xtrabackup_55  --defaults-file="/tmp/restore/backup-my.cnf" --prepare --target-dir=/tmp/restore
for creating ib_logfile*

xtrabackup_55 version 1.6.7 for Percona Server 5.5.16 Linux (x86_64) (revision id: undefined)
xtrabackup: cd to /tmp/restore
xtrabackup: This target seems to be already prepared.
xtrabackup: notice: xtrabackup_logfile was already used to '--prepare'.
xtrabackup: Temporary instance for recovery is set as followings.
xtrabackup:   innodb_data_home_dir = ./
xtrabackup:   innodb_data_file_path = ibdata1:10M:autoextend
xtrabackup:   innodb_log_group_home_dir = ./
xtrabackup:   innodb_log_files_in_group = 2
xtrabackup:   innodb_log_file_size = 5242880
130307 21:04:25 InnoDB: Using Linux native AIO
xtrabackup: Starting InnoDB instance for recovery.
xtrabackup: Using 104857600 bytes for buffer pool (set by --use-memory parameter)
130307 21:04:25 InnoDB: The InnoDB memory heap is disabled
130307 21:04:25 InnoDB: Mutexes and rw_locks use GCC atomic builtins
130307 21:04:25 InnoDB: Compressed tables use zlib 1.2.3
130307 21:04:25 InnoDB: Using Linux native AIO
130307 21:04:25 InnoDB: Warning: innodb_file_io_threads is deprecated. Please use innodb_read_io_threads and innodb_write_io_threads instead
130307 21:04:25 InnoDB: Initializing buffer pool, size = 100.0M
130307 21:04:25 InnoDB: Completed initialization of buffer pool
130307 21:04:25  InnoDB: Log file ./ib_logfile0 did not exist: new to be created
InnoDB: Setting log file ./ib_logfile0 size to 5 MB
InnoDB: Database physically writes the file full: wait...
130307 21:04:25  InnoDB: Log file ./ib_logfile1 did not exist: new to be created
InnoDB: Setting log file ./ib_logfile1 size to 5 MB
InnoDB: Database physically writes the file full: wait...
130307 21:04:25 InnoDB: highest supported file format is Barracuda.
InnoDB: The log sequence number in ibdata files does not match
InnoDB: the log sequence number in the ib_logfiles!
130307 21:04:25  InnoDB: Database was not shut down normally!
InnoDB: Starting crash recovery.
InnoDB: Reading tablespace information from the .ibd files...
InnoDB: Last MySQL binlog file position 0 107, file name /var/log/mysql/mysql-bin.000022
130307 21:04:26  InnoDB: Waiting for the background threads to start
130307 21:04:27 Percona XtraDB (http://www.percona.com) 1.1.8-20.1 started; log sequence number 59607052

[notice (again)]
  If you use binary log and don't use any hack of group commit,
  the binary log position seems to be:
InnoDB: Last MySQL binlog file position 0 107, file name /var/log/mysql/mysql-bin.000022

xtrabackup: starting shutdown with innodb_fast_shutdown = 1
130307 21:04:27  InnoDB: Starting shutdown...
130307 21:04:31  InnoDB: Shutdown completed; log sequence number 59607052
130307 21:04:31  innobackupex: completed OK!

这里的--apply-log指明是将日志应用到数据文件上，完成之后将备份文件中的数据恢复到数据库中：

然后再查看一下当前目录内容

root@client2:/tmp/restore# ll
total 79904
drwxr-xr-x  3 root  root      4096 Mar  7 21:04 ./
drwxrwxrwt 14 root  root      4096 Mar  7 21:04 ../
-rw-r--r--  1 root  root       260 Mar  7 21:01 backup-my.cnf
-rw-rw----  1 mysql mysql 69206016 Mar  7 21:04 ibdata1
-rw-r--r--  1 root  root   5242880 Mar  7 21:04 ib_logfile0
-rw-r--r--  1 root  root   5242880 Mar  7 21:04 ib_logfile1
drwxr-xr-x  2 root  root      4096 Mar  7 21:03 test/
-rw-r--r--  1 root  root        13 Mar  7 21:02 xtrabackup_binary
-rw-r--r--  1 root  root        23 Mar  7 21:02 xtrabackup_binlog_info
-rw-r--r--  1 root  root        36 Mar  7 21:04 xtrabackup_binlog_pos_innodb
-rw-r--r--  1 root  root        79 Mar  7 21:04 xtrabackup_checkpoints
-rw-r--r--  1 root  root   2097152 Mar  7 21:04 xtrabackup_logfile
然后把test目录复制到/var/lib/mysql目录
root@client2:/tmp/restore# rsync -avz test ib* /var/lib/mysql/
sending incremental file list
test/
test/db.opt
test/test.frm

sent 381 bytes  received 54 bytes  870.00 bytes/sec
total size is 8621  speedup is 19.82
root@client2:/tmp/restore# cd /var/lib/mysql/
root@client2:/var/lib/mysql# ll
total 77860
drwx------  8 mysql mysql     4096 Mar  7 21:06 ./
drwxr-xr-x 38 root  root      4096 Mar  7 19:52 ../
-rw-r--r--  1 root  root         0 Jan  5 14:22 debian-5.5.flag
drwx------  2 mysql mysql     4096 Feb 11 17:39 django/
-rw-rw----  1 mysql mysql 69206016 Mar  7 21:02 ibdata1
-rw-rw----  1 mysql mysql  5242880 Mar  7 21:02 ib_logfile0
-rw-rw----  1 mysql mysql  5242880 Mar  7 21:01 ib_logfile1
drwx------  2 mysql mysql     4096 Jan  5 22:55 monitor/
drwx------  2 mysql root      4096 Jan  5 14:22 mysql/
-rw-rw----  1 root  root         6 Jan  5 14:22 mysql_upgrade_info
drwx------  2 mysql mysql     4096 Jan  5 14:22 performance_schema/
drwxr-xr-x  2 root  root      4096 Mar  7 21:03 test/
drwxr-xr-x  2 mysql mysql     4096 Mar  7 19:58 xtrbackup/

然后再修改test的用户与组为mysql

root@client2:/var/lib/mysql# chown -R mysql:mysql test
root@client2:/var/lib/mysql# ll
total 77860
drwx------  8 mysql mysql     4096 Mar  7 21:06 ./
drwxr-xr-x 38 root  root      4096 Mar  7 19:52 ../
-rw-r--r--  1 root  root         0 Jan  5 14:22 debian-5.5.flag
drwx------  2 mysql mysql     4096 Feb 11 17:39 django/
-rw-rw----  1 mysql mysql 69206016 Mar  7 21:02 ibdata1
-rw-rw----  1 mysql mysql  5242880 Mar  7 21:02 ib_logfile0
-rw-rw----  1 mysql mysql  5242880 Mar  7 21:01 ib_logfile1
drwx------  2 mysql mysql     4096 Jan  5 22:55 monitor/
drwx------  2 mysql root      4096 Jan  5 14:22 mysql/
-rw-rw----  1 root  root         6 Jan  5 14:22 mysql_upgrade_info
drwx------  2 mysql mysql     4096 Jan  5 14:22 performance_schema/
drwxr-xr-x  2 mysql mysql     4096 Mar  7 21:03 test/
drwxr-xr-x  2 mysql mysql     4096 Mar  7 19:58 xtrbackup/

然后启动mysql，并查看test数据库的表里内容

root@client2:/var/lib/mysql# service  mysql start
mysql start/running, process 12730
root@client2:/var/lib/mysql# mysql -u root -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 36
Server version: 5.5.28-0ubuntu0.12.04.3-log (Ubuntu)

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> use test;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> select * from test;
+------+
| id   |
+------+
|    1 |
|    2 |
|    3 |
|    4 |
|    5 |
+------+
5 rows in set (0.01 sec)

可以看到数据库已经恢复完成

可能大家有个疑问，为什么我这里不像很多网上的文章里是在apply-log后，使用copy-back如果使用/usr/bin/innobackupex --copy-back命令后，会报Original data directory is not empty! at /usr/local/xtrabackup/bin/innobackupex line 538.恢复的目录必须为空。经查官网，这是xtrabackup的一个BUG。
innobackupex�Ccopy-back was run. With this bug fix, innobackupex�Ccopy-back operation if the destination is not empty, avoiding potential data loss or a strang combination of a restored backup and previous data. Bug Fixed: #737569 (Valentine Gostev) will now error out of the did not check that MySQL datadir was empty before

所以在apply-log后直接复制数据目录到数据库的位置上吧。