Solved Lost space on external drive - Lost 1TB of 2TB drive

I have a WD Red 2.0 TB drive (1.8 TB formatted) and have been watching it fill up (%used) for some time now. I have lost 1 TB to "unknown" according to WinDirStat. VSS is NOT RUNNING, which I read about in the tutorial here: http://www.sevenforums.com/tutorials/330-system-protection-turn-off.html.

So, what could be eating this space and how do I recover it?

FYI - the usual litany - No viruses; Disk Cleanup was run; Drive diagnostics pass; Chkdsk, defrag, etc. all OK.
Also, the thing I use the drive for is to maintain program libraries. I perform a lot of temporary folder copies and delete old copies. The recycle bin is empty. Have no idea why this space is lost.

I've always found WinDirStat results a bit cryptic.

Maybe you can get a more sensible result with a similar free application:

TreeSize Free - Quickly Scan Directory Sizes and Find Space Hogs

The usual suspects are hibernation file, System Restore points, page file, malware/virus, or some program doing something you don't expect it to do. For instance, we recently had a case here where someone was using a cloud backup program that was mis-configured and putting the backups on local drives, rather than in the cloud.

Trying your TreeSize suggestion (just the free version at the moment). Now, first I'll say I have already checked disk AND filesystem integrity before commenting that TreeSize and WinDirStat produced the same counts on small folders (say 100k files or less) but when it came to larger counts, they don't match at all.

I would not have doubted WinDirStat, but the TreeSize is reporting just over 1 million extra (not quite twice as many) files in the same 1.8 TB. Not sure where it is getting such a number, I may have to download the pro trial and check again. I will also export all the subfolder and file counts to see which of these programs has an accounting error.

Perhaps along the way, I will find a clue, though nothing jumps out at me just yet.

BBL

OK, I have a possible clue now, but going to get some sleep before picking up on this...

A snapshot of c:\users seems to have a recursion error.

c:\users was backed up to W:\drive_c\users\

The resulting w:\drive_c\users\<myaccount>\Local Settings contains a directory called Application Data which has another copy of Application Data inside itself and on and on a few times (recursively).

Now, the actual directory c:\users\<myaccount>\Local Settings is a protected directory for which I do not have access.

But before I poke further, I am going to get some sleep so as not to break anything.

Meanwhile, one of these disk utilities is wrong as WinDirStat suggests the USERS directory is about 79 GB (a likely number) on both C: and W: drives. However TreeSize reports the w: number as 811.2 GB which is not a likely number, but is a large percentage of the missing space on my W: drive.

Either way, sounds like trouble considering that both Microsoft and Western Digital diagnostics show the drives and filesystems to be in order.

FYI, my entire C: drive is only 222 GB. So how 1.0 TB on my W: backup drive can be "unknown" to WinDirStat and looking like 800+ GB in recursively stored files to TreeSize Pro, is a mystery I will have to sleep on before picking up again.

OK, so this Application Data recursion has the problem that I cannot simply delete it. Windows says the file names are too long.

Can you recommend a file zapper that will handle the approaching infinite recursion?

Starting a list of things that don't work:

• TreeSize (pro) seems to use Windows to do deletes, so doesn't work.
• WinDirStat won't even recognized the highest Application Data folder in the recursion - as if not there
• FileZilla won't even recognized the highest Application Data folder in the recursion - as if not there
• BeyondCompare (v4) won't delete the long file names.

UPDATE: so my solution is, and seems to be working, to walk into each directory and rename "Application Data" to "xx" and then CD into xx and repeat.
now, the paths are shorter and Windows is able to delete files.

Marking this SOLVED for now unless I run into any further difficulties.

FYI also found an opensource project that is in Beta to backup Windows junctions, but HAVE NOT TESTED IT YET. For future readers, search for Junction Box (open source). Also thanks for the tip about TreeSize Pro, which seems to have been a useful tool for diagnosing the problem. The price tag is a little stiff compared to freeware, but I like to support tools that get the job done. Perhaps they will make single user licenses more affordable for masses in the future. Thanks all!

P.S. I have recovered 1/2 TB already and am not finished, but assume the rest will play out OK.