Nick_Andreev That's well said - thanks. So the risk management here is really balancing the risk of running out of space at the array level, vs. running out of space at the volume level. Running out of space at the volume level is still a risk of course - since that datastore could go offline, vms could be corrupted, etc.
However running out of space at the array level is a risk with much greater impact and severity if it eventuates.
So what you are saying is accept the risk of an individual volume running out of space and don't accept the risk of the whole array running out of space.
In this environment capacity planning related to tracking growth of volumes is rather immature, so it would be just a matter of ramping up our trending/forecasting/monitoring of volume/datastore growth as much as possible.