User Error and "Disk Read Error" from Virtual PC
As I mentioned earlier this month I used VPC for the TechEd demo. Everything worked well but I had a strange problem that I couldn't quite work out. Today I took advantage of working at Microsoft and went and met some QA people from the VPC team and got an answer.
Here was my problem. My Virtual Hard Disk (.vhd) file for my Tech Ed demo worked fine off the external USB drive but whenever I copied the file and attempted to run a new Virtual Machine off the copied vhd file I would get a “Disk Read Error”.
After a little head scratching we (I'm using we in a very liberal sense) found the problem. When I received the USB drive it was preformated FAT32 and ready to go. I created the .vhd, loaded it up and was ready to rock and roll. Over time the .vhd file grew larger than the 4Gb FAT32 limit and VPC quite conveniently created a separate file with the extra information in it (the extension was v01). Now I actually had two files for my VPC:
When I went to copy the files to another drive I didn't copy the .v01 file so VPC failed to load it with a very cryptic “Disk Read Error”.
Here's what I learned:
- Keep your .vhd files on an NTFS drive
- Keep your .vmc files in the same directory as your vhd file (this just makes it easier to move stuff around)
But here's the best part. Paul helped me take my split .vhd files and create a single vhd file. Here's what he did:
- He created a new .vhd file and then used Norton's ghost to create an image file of my “split“ vhd file.
- He then created a new .vhd file and restored the image we just created to it.
Because we did all this on a NTFS drive we had no more split files!
The more I use VPC the more I'm impressed with it. Lots of different presenters at TechEd used it for their demos, if you haven't used it you should definitely give it a go?
