Don't Let Hard Disk space run out on your Hyper-V Host

So heres a pickle i got myself into and shoudlnt have.

We had a client who runs an ML350 as a Hyper-V host and has 3 guest machines an SBS2008, Terminal Server and an SQL Server.  So someone decided to dump a shit load of data onto a dynamic drive on one of the servers, which in turn used up all the remaining disk space on the HOST drive that the Guest VHD was sitting on.

If you have ever had a Guest VM display "Paused, Critical", this is one of those.  So arriving onsite to find that the Physical drive had 1mb of disk space left.  Since the only files on this drive where VHDs there was no imediate way of gaining space.

My breathing room came when i turned off the terminal server (the least important server) this cleared some Virtual Memory files from the drive which gave me about 3-4 gig of space to resume the paused servers and be able to successfully shut them down.  After shutting down the SQL i notice this in the Hyper V manager "Merging in progress" Whoops it seems as though someone has tried to delete a snapshot and not shut the server down to complete the merge.  I was presented with another problem, the merge was going to take all of my free disk space.

Sure enough i lost my diskspace again :(.

I found my solution by deleting a snapshot of the terminal server, lucky for me that the terminal server was on its own Physical HDD but the snapshots were on the disk with no space left, SO i got 9 gig back :).

Now at this point i though NO WAY was i trying anything else, so i started up the SQL server and resumed the SBS server and got them up and runnign with 4 gig free.

My solution to the problem was going to be adding new disks to the array in the server and expanding the size of the array, which i eventually did the next day and the server now has plenty of space to grow.

So rule of thumb ALWAYS make sure you have enough disk space to host Fixed VHDs of your important servers and leave the none important ones on other Physical HDDs.

FYI Go HERE this shows in quick steps how to compact a dynamic VHD if you have a disk space scare.

I will post after this as to the method i used to expand the array on the Server.

-Fr33ze