Tip on using differencing disks in Virtual PC

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I've been using differencing disks to test some deployment scripts: I have a base image that has the operating system and basic infrastructure (like BizTalk) on it, and I create a differencing disk off of that to test my deployment. Then I just delete the differencing disk when I want to try again. It works nicely (Undo disks would be another option here, but I often want to have more than one branch going at one time).

Anyway, last night at about 3am (well, this morning, I guess) I was pretty tired and I accidentally pointed my deployment VPC at the base disk image instead of the differencing disk. I deployed onto my clean image. It's not a huge deal, but it wasn't what I'd planned on happening, and it could have been really inconvenient if I'd not had a backup of the base image on another drive.

From now on, I'm setting the READ-ONLY flag on my base image. Just tried it and it works like a charm. Prevents you from accidentally using the parent VHD directly.


Posted Jul 01 2005, 09:49 AM by keith-brown
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Comments

Lorenzo Barbieri @ UGIblogs! wrote Un piccolo TIP, a volte salva la vita... :-D
on 07-01-2005 1:26 PM
mikeb wrote re: Tip on using differencing disks in Virtual PC
on 07-11-2005 4:05 PM
This is a reasonably common problem...

I think that the VPC Virtual Disk Wizard should offer to set the read-only flag on the base disk image when you create a differencing disk.