Wow, I just had quite an experience with my Highly Available Hyper-V virtual machine.
First of all, the HA feature with Hyper-V using Failover Clustering works REALLY well.
Second, I have to spend a bit more time thinking about what the heck I am doing before I go nuts again!
Okay, here I am, playing with snapshotting - taking snapshots, reverting, etc. Trying to document how things work and change.
Taking snapshots was a no brainer, everything worked fine.
When I deleted a snapshot I diligently shut down the VM and started monitoring the volume waiting for the merge to happen..I started at the screen for 20 minutes, watching, switching back to the Hyper-V console, watching the volume.
Finally, I tried to refresh the volume - boom! The volume is gone. Oh, cr**! iSCSI must be having problems - poke, troubleshoot, poke some more.
Suddenly, in a fit of frustration - duh, I have failover clustering set up. Check failover clustering - my VM is now running on Host 2. GAAA!!!
Okay, move the workload back. Get the merge to happen properly.
Now, revert.. Do a revert - boom, communication to the VM is lost (since the Host is serving up the console over RDP). I check Failover Clustering again - there is my VM on the other Host again - not properly reverted either.
Wow. The things to think about now.
Microsoft has done a brilliant job at using other Windows Server 2008 features WITH Hyper-V (think about it, Hyper-V is not much at all without all of the WS08 and System Center add-ons.) but the complexities of interplay between these components is not for the admin with a weak constitution.
Keep those skills up to par and be the admin that thinks out of the box.