openstack team mailing list archive

[Vishvananda Ishaya <vishvananda@xxxxxxxxx>]

On Nov 8, 2012, at 1:02 AM, Avishay Traeger <AVISHAY@xxxxxxxxxx> wrote:

> 
> Hi all,
> I had a few questions about snapshot support in Cinder:
> 1) a. Why is a snapshot a fundamentally different entity than a volume?
>   b. Is it because some back-ends don't support the same set of operations
> on snapshots?
>   c. Is this what the snapshot-to-volume operation was meant to achieve?
>   d. If a back-end supports nested snapshots, each snapshot will need to
> be converted to volume before a nested snapshot can be taken?
>   e. And in this case, will the back-end driver simply do nothing for the
> snapshot-to-volume operation?
> 2) Why can't you take snapshots of attached volumes?  I think most/all
> back-ends will be fine with it (of course they will be crash-consistent if
> the OS/application doesn't sync to disk).


I believe snapshot --force allows you to snapshot attached volumes.

Vish