日期:2014-05-16  浏览次数:20728 次

MySQL 复制+快照恢复误删除操作实验测试
下面假定2个场景:

场景1:主从架构,没有延迟,某DBA误操作:drop database 【复制+快照:在线备份】
场景2:存在不确定性或者风险性较大的操作,如升级测试,大表变更【啥事都在快照上折腾,不行大不了就将之删除】

场景2比较简单,随便在新建的一个快照上折腾,搞砸就把快照删除,再新建一个,2个字:随便玩
下面我们对场景1进行模拟

恢复方法:
① 恢复备库上的快照
② 根据binlog执行point-in-time恢复

先为备库创建快照

[root@localhost ~]# vgs
  VG   #PV #LV #SN Attr   VSize VFree
  vg     4   1   0 wz--n- 3.81G 1.81G
[root@localhost ~]# lvs
  LV    VG   Attr   LSize Origin Snap%  Move Log Copy%  Convert
  mysql vg   -wi-ao 2.00G    
  
[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      


[root@localhost ~]# mount /dev/vg/backup_mysql  /mnt/backup
[root@localhost ~]# cd /mnt/backup/
[root@localhost backup]# ls
lost+found  mysql
[root@localhost backup]# tar -jcv -f /mnt/snapshot/mysql.tar.bz2 *
[root@localhost ~]# lvremove --force /dev/vg/backup_mysql 
  Logical volume "backup_mysql" successfully removed


这里为什么要先备份快照再还原呢?
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

在 2013-10-12 9:57 某位无经验DBA错误地执行了drop database snapshots:

在备库上确认查看:

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| test               |
+--------------------+
可见库已经被删除了

同时在主库或者备库查看当前的二进制日志坐标并记录下来

[mysql@localhost mysql]$ mysqladmin -uroot -poracle shutdown
131012 09:59:36 mysqld_safe mysqld from pid file /mnt/lvm/mysql/data/localhost.localdomain.pid ended
[1]+  Done                    mysqld_safe


[root@localhost ~]# umount /mnt/backup
[root@localhost ~]# lvremove --force /dev/vg/backup_mysql 
  Logical volume "backup_mysql" successfully removed


[root@localhost ~]# umount /mnt/lvm                                 
[root@localhost ~]# mkfs -t ext3 /dev/vg/mysql
[root@localhost ~]# mount /dev/vg/mysql /mnt/lvm
[root@localhost ~]# tar -jxv -f /mnt/snapshot/mysql.tar.bz2  -C /mnt/lvm
[mysql@localhost ~]$ mysqld_safe &

通过binlog执行point-in-time恢复 

[mysql@localhost ~]$ mysqlbinlog --stop-datetime="2013-10-12 10:9:56" /mnt/lvm/mysql/data/mysql-bin.000008 | mysql -uroot -poracle

确认数据是否恢复:
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| snapshots          |
| test               |
+--------------------+
4 rows in set (0.00 sec)


mysql> use snapshots;
Database changed
mysql> show tables;
+---------------------+
| Tables_in_snapshots |
+---------------------+
| t