MySQL备份与恢复之真实环境使用冷备

朴灿烈づ我的快乐病毒、 2022-09-18 01:59 197阅读 0赞

## 一 真实环境使用冷备 ##

在上一篇文章（[MySQL备份与恢复之冷备][MySQL]）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 ##

![SouthEast][]

## 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][MySQL]
 *  [磁盘管理——LVM][LVM]

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>       All is well
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>       By Larry Wen

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[MySQL]: http://blog.csdn.net/justdb/article/details/14053345
[SouthEast]: /images/20220828/fd412156b4c549e6a1e56d7f228224fe.png
[LVM]: http://blog.csdn.net/justdb/article/details/10296697