Nir, thank you for your help and practical examples. I'll try to simulate.
In fact, most companies that actually have different offices do not share the same SAN/Storage structure , there are physical limitations and network details and time that make procedures impossible - As I said, storages that work differently, are also a limiting factor.
Export Domain, we can count today, but in six months, we don't know if it'll still be there.
Export domain is likely to remain in all 4.4.z, but I don't recommend to use it
because it will be impossible to support if you have issues with it.
Most hypervisors support Live Migrate/Off line migrate between "data centers". It would be great to have this feature up to oVirt 4.5.x
I guess that by "data center" you mean different physical data center and not
oVirt data center logical entity. In this case you may not be able to access storage
connected to one oVirt setup from the other oVirt setup. Is this the use case you
are interested in?
Please try to describe the use case in more detail.
Nir