Very Late Post: Virtual PC Differencing Disk

Hi all! This is a veeeeeeeery late post, but I always and still see people still struggling to do copy-paste VHD on their VPC. So guys hope this screenshot gallery can help for you to understand and hopefully use differencing disk.

So first, what is a differencing disk? Well — “A differencing disk is a virtual hard disk you use to isolate changes to a virtual hard disk or the guest operating system by storing them in a separate file” I think the simplest that I can articulate is you have a base VHD but instead of saving your changes to a base VHD you save it in another file, called differencing disk. But why do this? First is that you can actually save space by doing this, rather than duplicating each VHD only the changes on a COMMON base are saved. You can also chain your differencing disks but, thats for another day 🙂

To use differencing disks, you must first create your base. In the screenshots, I assumed that you already have this base (A clean image of what Operating system you want to clone, in my example a Windows Server 2003). What I do is I first create differencing disks and then use them later via “New Virtual Machine Wizard, Select Virtual Hard Disk”

So to create a differencing disk, on the VPC, click file then choose Virtual Disk Wizard. Click next until you arrive at Virtual Hard Disk Options.

on Virtual Hard Disk Options, choose Differencing. Select the parent or base that you created earlier and then click next up to finish.


We can now use this VHD, on the new Virtual Machine, choose an Existing Virtual Hard Disk and choose the newly created Differencing disk.


Hope that helps 🙂


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I'm John and in the daytime I am the Chief Technology Officer of VFTS.NET - a consulting firm that specializes on development and deployment of business solutions created with .NET framework on Windows platform and Windows infrastructure projects. I am a core member of the Philippine Windows Users Group, a contributor at the Microsoft Philippines Community forums and I regularly conduct technical sessions as well as other Microsoft technology events. I am a Microsoft Most Valuable Professional in the Cloud and Datacenter Management Technical Expertise but away from any keyboard I spend hours reading books, travel, explore, and being busy with my dog named Floppy.

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