I am trying to add snapshots feature introduced in 4.14 to addon-iscsi. But maybe I missed something from its concept.
As I studied other TM backends, snapshots are copies of currently used disk. Snapshots are never used directly. Last “created” or “reverted to” snapshot is marked as “active”. Active snapshot cannot be deleted. It means that I can never delete snapshot that was made as the first, because every time there have to be some active snapshot. Is there anything wrong?
Hi Michal,
You are right, I reached same conclusion while developing our addon-storpool.
I’ve found that the feature you are mentioning is available only for the persistent images.
You can find/track/ the feature request I’ve made regarding the matter.
Furthermore, if you have more than one snapshot in a chain you can not delete any snapshot in the chain to the root one even if the disk storage support it 
Lets hope this will change in the upcoming v5 
Kind Regards,
Anton Todorov