Ceph块存储-4·删除快照

删除一个受保护的快照困难重重，那就演示一下如何一步步操作进行删除的

一、删除镜像步骤思路：

• 将受保护的镜像修改为不受保护
• 删除镜像下面的所有快照
• 取消访问者挂载连接
• rbd删除镜像

二、开始实操

第一步：将受保护的镜像修改为不受保护

• 查看当前存储池情况

[root@crontrol7 ~]# rbd ls
mysql
mysql-snap1-1
mysql-snap1-2
new
[root@crontrol7 ~]# rbd showmapped
id pool image snap device    
0  rbd  mysql -    /dev/rbd0 

• 尝试直接删除镜像快照

[root@crontrol7 ~]# rbd snap purge mysql
Removing all snapshots: 0% complete...failed.
rbd: snapshot 'mysql-snap1' is protected from removal.

• 提示需要mysql-snap1快照是受保护的不能被移除，那就尝试解除受保护的状态

# 将mysql镜像中的快照mysql-snap1取消保护
[root@crontrol7 ~]# rbd snap unprotect mysql --snap mysql-snap1
2022-11-28 11:36:41.231903 7f22ee444700 -1 librbd::SnapshotUnprotectRequest: cannot unprotect: at least 2 child(ren) [104b2ae8944a,104f238e1f29] in pool 'rbd'
2022-11-28 11:36:41.231918 7f22ee444700 -1 librbd::SnapshotUnprotectRequest: encountered error: (16) Device or resource busy
2022-11-28 11:36:41.231927 7f22ee444700 -1 librbd::SnapshotUnprotectRequest: 0x5642da665db0 should_complete_error: ret_val=-16
rbd: unprotecting snap failed: (16) Device or resource busy
2022-11-28 11:36:41.235134 7f22ee444700 -1 librbd::SnapshotUnprotectRequest: 0x5642da665db0 should_complete_error: ret_val=-16

• 提示我cannot unprotect: at least 2 child(ren) [104b2ae8944a,104f238e1f29] in pool 'rbd'，那就把他们先进行删除（这个二个镜像也是从mysql-snap1这个快照克隆出来的，所以必须要先把他们删除）

[root@crontrol7 ~]# rbd rm mysql-snap1-1
Removing image: 100% complete...done.
[root@crontrol7 ~]# rbd rm mysql-snap1-2
Removing image: 100% complete...done.

• 然后就很顺利的将mysql-snap1快照取消保护了

[root@crontrol7 ~]# rbd snap unprotect mysql --snap mysql-snap1

第二步：删除镜像下面的所有快照

• 用rbd snap purge进行删除所有镜像的快照

[root@crontrol7 ~]# rbd snap purge mysql
Removing all snapshots: 100% complete...done.

• 尝试再删除镜像

[root@crontrol7 ~]# rbd rm mysql 
2022-11-28 11:39:47.365860 7fbe4859fd80 -1 librbd: image has watchers - not removing
Removing image: 0% complete...failed.
rbd: error: image still has watchers
This means the image is still open or the client using it crashed. Try again after closing/unmapping it or waiting 30s for the crashed client to timeout.

• 提示librbd: image has watchers - not removing，有人正在使用，不能进行删除

第三步：取消访问者挂载连接

• 查看下谁在挂载访问

[root@crontrol7 ~]# rbd status mysql
Watchers:
    watcher=192.168.88.253:0/3603526388 client.4172 cookie=18446462598732840961

• 原来小丑是我自己，自己挂载访问中，那就解除解除挂载和映射

# 解除挂载
[root@crontrol7 ~]# umount /mnt
# 解除映射
[root@crontrol7 ~]# rbd unmap mysql

# 再次确认watcher，显示none为正常
[root@crontrol7 ~]# rbd status mysql
Watchers: none

第四步：rbd删除镜像

• 最后就顺利删除了镜像

[root@crontrol7 ~]# rbd rm mysql
Removing image: 100% complete...done.