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
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!