Migration "starts" a VM?

[jessepeterson]

Hello!

This will sound a bit weird, but I purposely installed XCP-ng onto a non-Intel VT-d/AMD-V machine just to see how it would work. Not very well, as to be expected: I could not start any VMs because all the default templates are HVM templates and not e.g. pure (old school) PV — at least with XOA. I'm sure with enough xe shenanigans I could create a PV VM if I wanted. However I wanted to ask about migrations to and from these hosts.

I was able to migrate a stopped VM over to this older machine fine. Of course I couldn't start the VM. That was to be expected. However my challenge came when I wanted to migrate it back. It gave me the same errors as if I was starting the machine (no hosts available). So my question is: when you migrate a VM off a host does it "start" the VM — even in some preliminary way? I'm not sure why I was getting the 'no hosts available' message when trying to migrate a stopped VM.

Thanks!

[gskger]

@jessepeterson no host available usually indicates that the destination host has not the required ressources (ram/cpu/SR/ISO SR/passthrough devices/networking/mounted ISO) to start the VM. But the migration process does not actually start a stopped VM, as far as I know.

[jessepeterson]

@gskger huh, well then this is particularly odd because the VM came from the same destination! Literally it was migrate A->B (which went fine). Immediately try to migrate B->A with the no host available error. Host B here is the non-VT machine. Not to mention these were stopped VMs. They aren’t taking any resources - just disk.