Users can detach a storage domain from one data center and attach it to a different cluster. Then by importing the "unregistered" entities, the templates and VMs from the former data center can be "registered" to the latter data center. This mechanism was originally meant for disaster recovery - the storage device is being backed up and when the primary data center is disrupted, the storage device can be attached to a secondary data center where the templates and VMs can be registered to. However, people found out that this mechanism can work for upgrades. By detaching a storage domain from data center X and attaching it to data center Y that is of a newer version, the templates and VMs can be move between those versions without needing to export and import the VMs and without the risk of disrupting the primary data center. But now (oVirt 4.4) that templates and VMs need to be adjusted during upgrades, this wouldn't work without further changes. While we can treat this by adjusting the "registered" templates and VMs as if they were imported, this is conceptually wrong - entities should be registered to the same cluster version they were unregistered from.
this should be working correctly and VM should be upgraded to the target cluster level version during the import. close?
(In reply to Michal Skrivanek from comment #1) > this should be working correctly and VM should be upgraded to the target > cluster level version during the import. close? Yeah, until the next time we break this flow...