Richard Gass wrote:
If I remember correctly, there may have been an issue with writing to
the DFS when this code was written. During the suspend or migrate of
a non-persistent VM, the writing of the state needed to be very fast
in order to take a snapshot of the state, and continuously sync the
new changes until the current state was in sync with what was copied
to disk. In our case, the DFS was not a high performance filer but
just a machine with jbod attached disks. I think Mike would be able
to give more details about this one.
If that was the reason, then it seems to be vestigial now, since the VM
is stopped before beginning the state dump. At the time suspending
starts, the VM's state should not change anymore.
Migration is separate from this, because that just sends the state over
the network instead.
Our filer system isn't that high performance, but gigabit ethernet
connectivity to a bunch of spindles beats out staging to partition 3 on
a local disk that is shared with the OS and co-hosted VMs.
I've asked Mike for more information on what migration patches were put
on at IRP, but I maybe Mike has that information at hand too. :)
Greetings,
Mike.
