@dan2462 Did you get a resolution to your VDI issue? I have a similar problem as it seems hosts are locking up the VDI's on my shared iscsi storage and if they are shutdown and I try to boot them on an alternate host, I get the VDI not available error.

Depends a lot on what you have available. IMHO, I consider the system as disposable, since you can export the metadata, reinstall and import the metadata again. Or backup your VM, reinstall, restore. Or migrate out to another host, reinstall, re-migrate the VMs.

So many possibilities, that all depends on your setup.