A little background infomation , we had a customer calling saying they couldnt find a vhd file that used to be attached to a VM running on Hyper-V 2012 , there was no errors in the data protection manager console everything was green and the restore selection didnt show any options for recovery of data from that one vhd file.
After digging around we found a reason and got the customer data recovered , the steps to fall into the same trap is as follows
So adding the Hyper-V Guest to the DPM server results in the required result = Sucess
And under our restore selection we can see/browse/recover from the VHD
To reproduce we add a vhd to the VM
And due to lack of patience we will create a recovery point manually instead of waiting until next schedule kicks in
And we now have 2*vhd we can recover from.
So to reproduce we removed the vhd file from the VM kicked off another recovery point
and our protection group is still Ok as DPM reads the config from the Hyper-V Host and knows that there is only one vhd to protect.
and our recovery point can now only see the one vhd file
Until we go back in time .
Very simple when we have it right in front of us , when its a old VM where the drive was removed a few months ago so we had to dig though long term retention then its gets a little bit more confusing
We ended up finding it though Show All recovery points where the size was lower due to a full drive being removed (slightly bad example here as it a empty vhd so its 0.01gb in diff but you get the point.
So setup longer logging in VMM to see more than 3 months back pr default would also help