A while ago I talked about how I use Hyper-V in my house. One of the problems that I identified with my current setup was that I had most of my virtual machines (except for the Windows Home Server) running on the same disk as the system disk for the management operating system.
Apart from being a bad practice in general – this has always concerned me as that disk represents a pretty large single point of failure in my server (if that disk fails I will lose my domain controller, FTP server, SCVMM server, SCOM server, MED-V server and WDS server).
Recently I also discovered that the disk in question is the oldest (and slowest) disk in the system – and this is causing performance issues for all of the virtual machines running off of it.
Given all of this I decided to shuffle some disks out of other systems in my house and setup a higher performance two disk mirror for my system disk. This would at least address the issues of performance and resiliency to disk failure. The problem I faced was how to transfer my current system disk to a new RAID configuration.
After some failed attempts at using various cloning programs out there – it struck me that this was an ideal use of our backup technology. I would just backup the current system disk – and restore it to the new physical disk.
As this was just going to be a “once off” backup – I did not want to spend the time to setup a full enterprise backup solution (like DPM) but just wanted to use Windows Server Backup.
I knew that Windows Server Backup does not support Hyper-V by default – so went off to get the details of how to enable this from the appropriate KB article (http://support.microsoft.com/kb/958662) and was pleasantly surprised to find that a “Fix it” has been made for this issue – so I was able to complete this step without too much trouble.
Side note: You may wonder what happens if you do not enable this fix it. Simply put, by default Windows Server Backup will not engage our VSS backup components. This means that it will just copy the files of the virtual machines without doing anything to prepare them for backup. If your virtual machines are turned off – this is fine. If your virtual machines are running – this can result in your backup having corrupt data in the virtual machines (but it will not affect the currently running virtual machines).
Once you enable the fix it – there is nothing in the Windows Server Backup user interface that indicates that anything is different. But now when you backup a drive that contains virtual machines we will either use VSS inside the virtual machine in order to guarantee a valid backup is taken – or we will momentarily put the virtual machine into a saved state (if VSS is not supported by the guest operating system) and resume it after the backup is taken.
Most of my virtual machines support VSS, but I did fire up a Windows XP virtual machine just to watch the backup progress – otherwise there is no way for me to know that anything actually happened to the virtual machines :-)
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