MySQL备份与恢复之真实环境使用冷备

一 真实环境使用冷备

       在上一篇文章（MySQL备份与恢复之冷备）中，我们提到了冷备。但是有个问题，我们存储的数据文件是保存在当前本地磁盘的，如果这个磁盘挂掉，那我们存储的数据不就丢失了，这样备份数据不就功亏一篑，劳而无功。所以真实环境中我们多准备几块磁盘，然后再在这些磁盘上搭建LVM，把MySQL的数据目录挂载到LVM上，这样数据就不是存储在当前磁盘上，就可以保证数据的安全性。

二 示意图

 

三 真实环境使用冷备模拟

第一步，需要提前规划好磁盘，这里做模拟，添加两磁盘

 

第二步，对磁盘进行分区

[root@serv01 ~]# fdisk /dev/sdb
[root@serv01 ~]# fdisk /dev/sdc

[root@serv01 ~]# ll /dev/sd[bc]1
brw-rw----. 1 root disk 8, 17 Sep 10 18:06 /dev/sdb1
brw-rw----. 1 root disk 8, 33 Sep 10 18:09 /dev/sdc1

 

第三步，yum安装lvm2

[root@serv01 ~]# yum install lvm2 -y

 

第四步，创建物理卷

[root@serv01 ~]# pvcreate /dev/sdb1 /dev/sdc1 
  Physical volume "/dev/sdb1" successfully created
  Physical volume "/dev/sdc1" successfully created

 

第五步，创建卷组

[root@serv01 ~]# vgcreate data /dev/sdb1 /dev/sdc1 
  Volume group "data" successfully created

 

第六步，创建逻辑卷

[root@serv01 ~]# lvcreate -L 2G -n mydata data
  Logical volume "mydata" created

 

第七步，格式化磁盘

[root@serv01 ~]# mkfs.ext4 /dev/data/mydata 
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
131072 inodes, 524288 blocks
26214 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=536870912
16 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks: 
  32768, 98304, 163840, 229376, 294912

Writing inode tables: done                            
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 28 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

 

第八步，冷备

[root@serv01 ~]# ls /usr/local/mysql/data/
crm      ib_logfile0  mysql-bin.000001  mysql-bin.000005  mysql-bin.000009  mysql-bin.000013  mysql-bin.index      test
game     ib_logfile1  mysql-bin.000002  mysql-bin.000006  mysql-bin.000010  mysql-bin.000014  performance_schema
hello    larrydb      mysql-bin.000003  mysql-bin.000007  mysql-bin.000011  mysql-bin.000015  serv01.host.com.err
ibdata1  mysql        mysql-bin.000004  mysql-bin.000008  mysql-bin.000012  mysql-bin.000016  serv01.host.com.pid

[root@serv01 opt]# tar -cvPzf mysql01.tar.gz /usr/local/mysql/data/

第九步，删除数据库文件

[root@serv01 ~]# rm -rf /usr/local/mysql/data/*

 

第十步，挂载

[root@serv01 ~]# mount /dev/data/mydata /usr/local/mysql/data/
[root@serv01 ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2             9.7G  2.4G  6.8G  27% /
tmpfs                 188M     0  188M   0% /dev/shm
/dev/sda1             194M   25M  160M  14% /boot
/dev/sda5             4.0G  160M  3.7G   5% /opt
/dev/sr0              3.4G  3.4G     0 100% /iso
/dev/mapper/data-mydata
                      2.0G   67M  1.9G   4% /usr/local/mysql/data

 

第十一步，将挂载信息写入配置文件

[root@serv01 opt]# echo "/dev/mapper/data-mydata /usr/local/mysql/data ext4 defaults 1 2" >> /etc/fstab 
[root@serv01 opt]# tail -n1 /etc/fstab 
/dev/mapper/data-mydata /usr/local/mysql/data ext4 defaults 1 2

 

第十二步，停掉数据库

[root@serv01 ~]# /etc/init.d/mysqld stop
 ERROR! MySQL server PID file could not be found!
[root@serv01 ~]# ps -ef | grep mysqld
root      1055     1  0 18:05 ?        00:00:00 /bin/sh /usr/local/mysql/bin/mysqld_safe --datadir=/usr/local/mysql/data --pid-file=/usr/local/mysql/data/serv01.host.com.pid
mysql     1332  1055  0 18:05 ?        00:00:00 /usr/local/mysql/bin/mysqld --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --plugin-dir=/usr/local/mysql/lib/plugin --user=mysql --log-error=/usr/local/mysql/data/serv01.host.com.err --pid-file=/usr/local/mysql/data/serv01.host.com.pid --socket=/tmp/mysql.sock --port=3306
root      1885  1490  0 18:18 pts/0    00:00:00 grep mysqld

[root@serv01 ~]# pkill -9 mysql
[root@serv01 ~]# ps -ef | grep mysqld
root      1888  1490  0 18:18 pts/0    00:00:00 grep mysqld
[root@serv01 ~]# chown mysql.mysql /usr/local/mysql/data/ -R

[root@serv01 opt]# ll /usr/local/mysql/data/
total 0
[root@serv01 opt]# ll /usr/local/mysql/data/ -d
drwxr-xr-x. 2 mysql mysql 4096 Sep 10 18:17 /usr/local/mysql/data/

 

第十三步，恢复数据

[root@serv01 opt]# tar -xPvf mysql01.tar.gz 

 

第十四步，启动数据库，登录MySQL，然后查看数据是否丢失

[root@serv01 opt]# /etc/init.d/mysqld start
Starting MySQL SUCCESS! 

[root@serv01 ~]# mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
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> use larrydb;
Database changed
mysql> show tables;
+-------------------+
| Tables_in_larrydb |
+-------------------+
| class             |
| stu               |
+-------------------+
2 rows in set (0.00 sec)

mysql> select * from class;
+------+--------+
| cid  | cname  |
+------+--------+
|    1 | linux  |
|    2 | oracle |
+------+--------+
2 rows in set (0.01 sec)

mysql> select * from stu;
+------+---------+------+
| sid  | sname   | cid  |
+------+---------+------+
|    1 | larry01 |    1 |
|    2 | larry02 |    2 |
+------+---------+------+
2 rows in set (0.00 sec)

 

第十五步，使用LVS的快照功能创建快照，快照不需要格式化。

[root@serv01 opt]# lvcreate -L 100M -s -n smydata /dev/data/mydata 
  Logical volume "smydata" created

 

第十六步，挂载

[root@serv01 opt]# mount /dev/data/smydata /mnt
[root@serv01 opt]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2             9.7G  2.4G  6.8G  27% /
tmpfs                 188M     0  188M   0% /dev/shm
/dev/sda1             194M   25M  160M  14% /boot
/dev/sda5             4.0G  161M  3.7G   5% /opt
/dev/sr0              3.4G  3.4G     0 100% /iso
/dev/mapper/data-mydata
                      2.0G   98M  1.8G   6% /usr/local/mysql/data
/dev/mapper/data-smydata
                      2.0G   98M  1.8G   6% /mnt

 

第十七步，模拟数据丢失和验证快照的数据不会受本身数据的影响

[root@serv01 opt]# cd /mnt
[root@serv01 mnt]# ls
crm          ib_logfile1       mysql-bin.000003  mysql-bin.000008  mysql-bin.000013  mysql-bin.index
game         larrydb           mysql-bin.000004  mysql-bin.000009  mysql-bin.000014  performance_schema
hello        mysql             mysql-bin.000005  mysql-bin.000010  mysql-bin.000015  serv01.host.com.err
ibdata1      mysql-bin.000001  mysql-bin.000006  mysql-bin.000011  mysql-bin.000016  serv01.host.com.pid
ib_logfile0  mysql-bin.000002  mysql-bin.000007  mysql-bin.000012  mysql-bin.000017  test

#进入数据目录，创建一个文件
[root@serv01 ~]# cd /usr/local/mysql/data/
[root@serv01 data]# touch aa01.txt

#进入快照挂载目录，发现没有这个文件
[root@serv01 mnt]# ls aa01.txt
ls: cannot access aa01.txt: No such file or directory

 

第十八步，备份数据

[root@serv01 mnt]# cd /databackup/
[root@serv01 databackup]# ll
total 976
-rw-r--r--. 1 root root 995761 Sep 10 17:47 mysql01.tar.gz
[root@serv01 databackup]# /etc/init.d/mysqld status
 SUCCESS! MySQL running (2198)
[root@serv01 databackup]# tar -cvzf mysql02.tar.gz /mnt

[root@serv01 mnt]# rm -rf /usr/local/mysql/data/*
[root@serv01 mnt]# /etc/init.d/mysqld stop
 ERROR! MySQL server PID file could not be found!
[root@serv01 mnt]# pkill -9 mysql
[root@serv01 mnt]# ps -ef | grep mysqld | grep grep -v

[root@serv01 mnt]# cd /usr/local/mysql/data/
[root@serv01 data]# ll
total 0

 

第十九步，恢复数据，启动数据库，登录MySQL，然后查看数据是否丢失

[root@serv01 data]# tar -xvf /databackup/mysql02.tar.gz

[root@serv01 data]# ls
mnt
[root@serv01 data]# cd mnt/
[root@serv01 mnt]# mv ./* ../

[root@serv01 mnt]# cd ..
[root@serv01 data]# ls
crm      ib_logfile0  mysql             mysql-bin.000004  mysql-bin.000008  mysql-bin.000012  mysql-bin.000016    serv01.host.com.err
game     ib_logfile1  mysql-bin.000001  mysql-bin.000005  mysql-bin.000009  mysql-bin.000013  mysql-bin.000017    serv01.host.com.pid
hello    larrydb      mysql-bin.000002  mysql-bin.000006  mysql-bin.000010  mysql-bin.000014  mysql-bin.index     test
ibdata1  mnt          mysql-bin.000003  mysql-bin.000007  mysql-bin.000011  mysql-bin.000015  performance_schema

[root@serv01 data]# /etc/init.d/mysqld start
Starting MySQL SUCCESS! 
[root@serv01 data]# mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
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> 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)

四 相关阅读

• MySQL备份与恢复之冷备
• 磁盘管理——LVM

  我的邮箱：[email protected]   新浪微博：@jutdb         
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  All is well
  2013年11月3日
  By Larry Wen

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