Windows Server 2008 R2 reports full disk, but files do not add up

Question

I have a web server running Windows Server 2008 R2 Enterprise. It's C:\ drive is 100 GB in size.

We started getting errors from IIS and discovered that the C:\ drive, surprisingly so, was reported to be full. This is where it gets strange: I changed folder options to show hidden files and protected system files, and then did a right click/Properties on everything on C:\ to see the cumulative size, which is only 13.7 GB (more in line of what is usually on that server).

• The recycle bin is empty
• There is no page file on C:\ (explicitly turned off)
• vssadmin list shadows showed no shadows ("No items found that satisfy the query").
• No BitLocker

Chkdsk results:

104754175 KB total disk space.
100648156 KB in 62945 files.
    46616 KB in 16972 indexes.
        0 KB in bad sectors.
   151415 KB in use by the system.
    65536 KB occupied by the log file.
  3907988 KB available on disk. (note: this is after I cleared about 4GB)

Where are the remaining 86.3 GB that are supposedly on that disk?

Answer (also below): WinDirStat helped identify C:\Windows\Temp\php53_errors.log as the culprit. Unfortunately it was impossible to identify this with regular tools. Thanks to everyone who helped point me to the tool!

Solution 1

WinDirStat indeed solved the mystery. Thanks to Robert, Brent, and user72593!

The main file that ate up all the space was C:\Windows\Temp\php53_errors.log - at a massive 84.7 GB size. Not sure what all those errors are; we run Wordpress/PHP on this server, so it must come from there. Also not sure why a right click/Properties on C:\Windows doesn't report anything in the Temp folder, that's pretty stupid.

P.S.: Seems like I'm not the only one with a massive php53_errors.log file: https://stackoverflow.com/questions/13540489

Solution 2

Assuming you're not running BitLocker which has been known to cause issues like this, I would run vssadmin to see if you have shadow copy chewing up space from failed backups, do you run some backup softeare? If neither of those apply then sounds like you have some partition corruption (if WinDirStat also shows the partition to have ample free space) I would run a repair of the partition by right-clicking on the drive letter, going to properties and tools and choosing the repair option so see if that corrects things.

Comments

[user72593]

Have you already run WinDirStat or TreeSize or any similar application that would look inside your System Volume Information and other system folder to account for ALL the files? TreeSize can catalog things pretty quickly and tell you if there is actual data somewhere.

[AX1]

Running WinDirStat now! Will report what I find.

[user72593]

Glad you've got it sorted !