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StewartTechnologiesFlag for United States of America

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Significant decrease of drive space C:

Hello, I have noticed a sudden 50% drivespace reduction of the C: drive. I have checked log folders sizes. There is nothing that i know of that could trigger the sudden decrease of the drive space.

Anywhere else i can check. or what can cuase C: drive size reduction

OS Windows SBS 2011 SP1

Thank you.
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Alan Hardisty
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@alanhardisty - I think you misinterpreted the question.  StewTech is trying to find out why his disk space usage decreased, not increased.

@StewTech - Do any user accounts have access to C:?  Is it possible that someone deleted any significant volume of user-specific content (e.g., photos, music, apps)?

This is drastic, but you could 1) export current folder structure/sizes, 2) take a backup of C: to fresh media, 3) restore the last previous backup of C:, 4) compare restored folder structure/sizes to identify the reduction, and 5) restore the backup taken in step 2 if the reduction was valid or inconsequential.
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i guess the post is a bit confusing. My C:  free space went from 83.0GB to 38.0GB in 2 days.

My free space is decreasing. that is the problem.

hope this helps.
Have you looked through my article?

When was the server installed?

Have you moved WSUS from the C: drive to another drive (if you have one)?

Did you move the Exchange Database to another drive (if you have one)?

Have your users been moving mailboxes / adding / deleting accounts from Mobile Phones en-masse lately?
It's either your Exchange Database (most likely culprit), the IIS log files, automated backups or WSUS.

From the root of your C drive (in Windows Explorer), check the properties of every folder at the root level (there shouldnt be that many. Write down the file size of every folder.

Then wait a few hours (or the next day) and check them all again.
That should tell you what folder to start looking in.
(Enable the view option to show hidden and system folders)
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also check shadow copies.  If you configured them (or I think even left them as default) they could be using a LOT of space.  Check the tab on the properties of a drive letter.
@StewTech - apologies - It looks like I"m the one that misunderstood the issue.  A lot of good suggestions have been offered to help identify the reason behind the decrease in free space.
download this software

windirstat from This is free.

This will make a map of your C: like this

rest is very simple :)
My vote goes for ve3ofa and his solution.
I downloaded the Windirstat tool and ran it. I was able to determine the cause of the free space decrease on the C: drive.

it was an Sql tmp file from symantec. Took care of that.

Thank you all for your contributions.