Hyper-V Snapshot Issue on Exchange server

Question

Hyper-v 2008 R2
I have a 2TB host in which I am running 2 VM's
Exchange was a 900gb Fixed disk VM
Terminal server 200gb Fixed.
I was working remotely on my iPhone on the Exchange server (I know, don't ask) when I think I accidentally hit the snapshot button inside of Hyperv Manager.
The user called and said the server stopped working and I quickly realized it unexpectedly rebooted and the Address Book service failed to start automatically. I was trying to navigate my way around on my phone and thats when I think I hit the snapshot button.
I didn't realize this until 2 days later when looking inside my VHDS folder that a new AVHD file was created that was 818gb and timestamped exactly when I was working on it remotely.
The original VHD file was dated 2 days earlier and 825gb
The snapshot is NOT showing up in Hyperv Manager at all so I'm not sure what the best next steps are.
I figured I would first take the VM offline and export it to a another location before doing anything to preserve the Exchange server. I am running a Barracuda so I'm not worried about losing any email as that will trap everything.
I noticed in the settings of Hyperv Manager for Exchange that it is using the AVHD file as the primary file.
Questions
1 - If I take it offline, shouldn't the 2 files merge without me doing anything else? I just wasn't sure since the Snapshot does not show up in SCVMM or Hyperv manager.
2 - I should be able to see this process in SCVMM?
3- How long will it take to merge 800gb? I've seen varying results depending on disk speed, etc.
With an exchange server, this obviously needs to be done delicately without data loss. I assume my statement about the original Exporting of the VM will cover my bases for that?
Thoughts on how to proceed?
Thanks!
Jim

Answer 1

Hyper-V 2008 R2..  This was prior to live merging of snapshots.
What I am guessing is: the snapshot was taken, and in panic the snapshot was deleted.
This means that the VM remains in a snapshotted state, but the snapshot is removed from the GUI.  Deleted snapshots do not show up in the GUI, but remain in place until the background merge process happens / is allowed to happen.
The only way for this snapshot to merge is to power off the VM and wait
for the merge to happen.
You can verify this by looking for pending merge events in the Hyper-V event logs (  events -> applications and services -> Microsoft -> Windows -> Hyper-V*
if you want to before scheduling your offline time.
Merge speed depends on the amount of change.  You cannot predict it, you can only test to know.
Exporting the VM will keep the disk structure as it is.  Taking a snapshot then exporting the snapshot will create a single VHD (but will take just as long as the merge itself if not longer).
I would check the logs for pending merge events (just to confirm, safety), if they exist then schedule some downtime and power off the VM for the duration of your maintenance window and watch for the merge.
Or, don't bother checking for the merge events and just schedule the downtime and power off the VM and wait.
Brian Ehlert
http://ITProctology.blogspot.com
Learn. Apply. Repeat.