* Like Case 2, the benefit isn't clear to me. In a scenario where you
use both QEMU and LVM snapshots there is now an extra management
overhead of cleaning up 2 snapshots instead of just 1 when the user
wants to delete a snapshot. I think this will be a headache.
My understanding is internal snapshots is obvious fast in both deleting and
reading, and I have similar questions, Dietmar, could u tip more how you use
this case while 2 snapshot layer exist?
To be honest, I don't really understand what you talk about here. There are
simply
different storage types and file formats. There are several storage types with
support for internal snapshots:
* traditional qcow2 files on normal file system
* newer file systems (zfs, btrfs)
* lvm (new dm-thin pools)
* RDB (ceph)
* sheepdog
* iSCSI and nexenta API
*...
And you simply want to allow an external library to create/remove the snapshot
for you.