I’m not sure if this is has always been this way, but in vCloud 5.1.2, if you modify a VM that’s on a datastore that has been disabled in vCloud, vCloud will will request that vCenter relocate VM to a non-disabled datastore.
I have several datastores that are disabled due to usage and this affected me when user wanted to modify the RAM on a VM. I shut down the VM, changed the RAM and then noticed the update was taking a long time. I jumped into vCenter to see the VM being migrated to a new datastore, and since this enviroment’s storage is very slow, the VM ended up being down for 30 minutes.
One workaround would be to quickly re-enable the datastore, make the change and disable the datastore again. Of course, someone could come along and provision to the datastore while you’re making the change.
It’s not something that should be done too often, but you could also make the memory change directly in vCenter and vCloud will pick up the change.
My change was done in a test environment so it wasn’t a big deal, but it’s useful to know in case the work is being done in a production environment where you probably have a change window that could be missed due to how long it takes to migrate the VM.