I've been scratching my head the past few days.

My main computer is a notebook running Windows Vista Enterprise SP1 with a 110 GB C: drive and an external 150 GB F: drive. The only thing that's installed on the C: drive is the OS and applications - all my data is on the F: drive. Despite this, my C: drive was becoming full and was giving me warnings that it had less than 2 GB of free space. Very puzzling.

I ran the Disk Cleanup utility but it didn't show anything very large to delete. I manually checked the temp directories, took a look at the page and hibernate files, and listed the disk usage information for all the directories. According to my calculations, I was only using 30 GB or so. Where was the rest of my disk space being used?

After a little searching, I found an article on the My Digital Life site on how to use the vssadmin.exe utility to see how much space is being allocated for the Volume Shadow Copy service. So I opened a command prompt (with admin privileges) and ran the following command:

vssadmin list shadowstorage

Sure enough, that's where my drive space had gone! Since the maximum limit on my machine was unbounded, Vista was swallowing up all my free space. The author details how to use the vssadmin.exe utility to limit the maximum storage space, but there is also another article on how to use the Explorer GUI to do the same thing.

My computer is now reporting 77 GB of free space and both of us are happy campers once again.