快照和复制技术的结合可以保证我们得到一个实时的在线MySQL备份解决方案 当主库发生误操作时，只需要恢复备库上的快照，然后再根据binlog执行point-in-time的恢复即可 。下面假定一个场景：主从架构，没有延迟，某DBA误操作：drop database 接下来我们按照以上场景进行备份恢复模拟测试。
1.主库准备测试数据
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mysql> create database cnfol; Query OK, 1 row affected (0.00 sec) mysql> create table cnfol.t (id int primary key); Query OK, 0 rows affected (0.02 sec) mysql> insert into cnfol.t select 1; Query OK, 1 row affected (0.01 sec) Records: 1 Duplicates: 0 Warnings: 0 mysql> insert into cnfol.t select 2; Query OK, 1 row affected (0.00 sec) Records: 1 Duplicates: 0 Warnings: 0
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到备库确认：
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mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | cnfol | | mysql | | test | +--------------------+ 4 rows in set (0.00 sec) mysql> select * from cnfol.t; +----+ | id | +----+ | 1 | | 2 | +----+ 2 rows in set (0.00 sec)
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2.加个全局读锁 在备库
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mysql> flush tables with read lock; Query OK, 0 rows affected (0.00 sec)
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3.为备库所在分区创建快照
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[root@localhost ~]# lvcreate --size 1G --snapshot --name backup_mysql /dev/vg/mysql Logical volume "backup_mysql" created [root@localhost ~]# lvs LV VG Attr LSize Origin snap% Move Log Copy% Convert backup_mysql vg swi-a- 1.00G mysql 0.00 mysql vg owi-ao 2.00G
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4.获取二进制日志坐标
在备库：
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mysql> show master status; +------------------+----------+--------------+------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | +------------------+----------+--------------+------------------+ | mysql-bin.000003 | 727 | | | +------------------+----------+--------------+------------------+ 1 row in set (0.00 sec)
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解锁 在备库：
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mysql> unlock tables; Query OK, 0 rows affected (0.00 sec)
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5.挂载快照
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[root@localhost ~]# mount /dev/vg/backup_mysql /mnt/backup [root@localhost ~]# cd /mnt/backup/mysql/data/cnfol/ && ls -alh 总计 32K drwx------ 2 mysql dba 4.0K 10-14 09:57 . drwx------ 5 mysql dba 4.0K 10-14 09:57 .. -rw-rw---- 1 mysql dba 61 10-14 09:57 db.opt -rw-rw---- 1 mysql dba 8.4K 10-14 09:57 t.frm -rw-rw---- 1 mysql dba 14 10-14 09:57 t.MYD -rw-rw---- 1 mysql dba 2.0K 10-14 10:06 t.MYI
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6.主库某无经验DBA误操作
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mysql> drop database cnfol; Query OK, 1 row affected (0.05 sec)
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记录下此时时间：2013-10-14 10:17:10
备库确认是否存在库cnfol:
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mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | mysql | | test | +--------------------+ 3 rows in set (0.01 sec)
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7.备份快照
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[root@localhost backup]# pwd /mnt/backup [root@localhost backup]# tar -jcv -f /mnt/snapshot/mysql.tar.bz2 *
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这里做备份的原因有2点 * 其一，昂贵的IO，因为磁头要在快照区和系统区来回跑 * 其二，快照区空间不足，因为是COW原理
8.删除快照
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[root@localhost ~]# umount /mnt/backup [root@localhost ~]# lvremove --force /dev/vg/backup_mysql Logical volume "backup_mysql" successfully removed
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9.格式化备库所在分区
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[mysql@localhost ~]$ mysqladmin -uroot -poracle shutdown 131014 10:32:40 mysqld_safe mysqld from pid file /mnt/lvm/mysql/data/localhost.localdomain.pid ended [1]+ Done mysqld_safe [root@localhost ~]# umount /mnt/lvm [root@localhost ~]# mkfs -t ext3 /dev/vg/mysql [root@localhost ~]# mount /dev/vg/mysql /mnt/lvm [root@localhost ~]# lvs LV VG Attr LSize Origin snap% Move Log Copy% Convert mysql vg -wi-ao 2.00G [root@localhost ~]# vgs VG #PV #LV #SN Attr VSize VFree vg 4 1 0 wz--n- 3.81G 1.81G
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10.解压缩快照到备库所在分区
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# tar -jxv -f /mnt/snapshot/mysql.tar.bz2 -C /mnt/lvm/ [root@localhost lvm]# pwd /mnt/lvm [root@localhost lvm]# ls lost+found mysql
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11.启动MySQL
12.利用binlog执行point-in-time恢复
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[mysql@localhost ~]$ mysqlbinlog --stop-datetime="2013-10-14 10:17:10" /mnt/lvm/mysql/data/mysql-bin.000003 | mysql -uroot -poracle
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13.确认数据
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mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | cnfol | | mysql | | test | +--------------------+ 4 rows in set (0.00 sec) mysql> select * from cnfol.t; +----+ | id | +----+ | 1 | | 2 | +----+ 2 rows in set (0.00 sec)
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