[fedora-virt] Internal Snapshots & Used-Space

[Jorge Fábregas]

On 10/10/2013 07:42 AM, Kevin Wolf wrote:
> qcow2 has a reference count for each cluster. Taking a snapshot
> basically means increasing the refcount of each currently used cluster,
> it's not much more. Deleting a snapshot means decreasing the refcount,
> and only once the refcount reaches zero, the cluster is freed. (Which
> is, by the way, a much cheaper operation than deleting an external
> snapshot, which means moving actual user data to a different image.)
> 
> So no, it's not less efficient, there is no duplication of data, but
> data is kept as long as there is still a snapshot using it.

Thanks for the insight Kevin!

Best regards,
Jorge