I just realise I don't have 50gb of my 250gb hard disk. What happened??? How took it away??
Vista and the mysteriously shrinking disk space.
Symptoms
The OS C: disk is running out of space. Out of 250 GB only a few GB remaining.This seems strange as the actual space occupied by files appears to be in the range of 88Gb.
Investigation
After looking for causes and solutions to this problem, it appears that the Vista
restore and shadow copy system settings are the problem.
After opening a command window as an Administrator (All Programs.Accessories.CommandPrompt, RightClick on Command prompt and Run As Administrator) you can check the space used by restore points and shadow copies with vssadmin List ShadowStorage command.
This clearly indicated that Shadow Copy Storage was the major issue consuming over 134 GB of space. The Maximum Shadow Copy Storage Space was also set to UNBOUNDED (UNLIMITED)
Problem Solution
Right click on the OS C: volume and select Properties. In the Dialog box select the Disk Cleanup tool and select Files from all users
From the More Options tab select Clean Up and confirm the delete.
Once the shadow copies were deleted I was able to recover my 'missing' disk space!
Resize ShadowCopy
Finally, as a good measure for trying NOT TO REPEAT this issue in the future I've used the vssadmin utility to resize the maximum ShadowCopy size to 30 GB which is approximately 15% of my drive space.
vssadmin resize shadowstorage /for=C: /on=C: /maxsize=30GB
So be aware of hidden Vista gems and take control of your own destiny!