[SOLVED] Chkdsk "Replacing invalid security id...", but now lots of files are 0 length!

[misterbirra]

I have a Western Digital 1TB external HDD. While doing some very simple "housekeeping" I've decided to run a chkdsk (on Windows 10 x64). Well... I shouldn't have done that! Now I'm on a mess with lots of files.

First, chkdsk reported that the drive had filesystem errors. Without continuing, I've checked the Event Viewer and there were messages like:

Stage 1: Examining basic file system structure ...
    Found corrupt basic file structure for "<0x3,0xfe4>"
        ... queued for offline repair.
    Found corrupt basic file structure for "<0x3,0x101c>"
        ... queued for offline repair.
    Found corrupt basic file structure for "<0x3,0x103e>"
        ... queued for offline repair.
    Found corrupt basic file structure for "<0x3,0x17ae>"
        ... queued for offline repair.
    Found corrupt basic file structure for "<0x3,0x187d>"
        ... queued for offline repair.
    Found corrupt basic file structure for "<0x3,0x187f>"
        ... queued for offline repair.
[.............]

There were also lines with exact filenames instead of just "<0x3,0x187f>" codes...
So before panic, I've used WD's Data Lifeguard Diagnostic to check for any drive failure. The test passed and everything was OK.
So I've re-run chkdsk, this time telling it to Fix the errors.......

The procedure finished in a couple of minutes. The event log said:

Chkdsk was executed in spotfix mode on a read-write volume.
Checking file system on Z:
Volume dismounted.  All opened handles to this volume are now invalid.
Volume label is PileOfPi1.

Examining 978 corruption records ...

Record 1 of 978: Corrupt File "<0x3,0xfe4>" ... Replacing invalid security id with default security id for file FE4.
corruption found and fixed.
Record 2 of 978: Corrupt File "<0x3,0x101c>" ... Replacing invalid security id with default security id for file 101C.
corruption found and fixed.
Record 3 of 978: Corrupt File "<0x3,0x103e>" ... Replacing invalid security id with default security id for file 103E.
corruption found and fixed.
Record 4 of 978: Corrupt File "<0x3,0x17ae>" ... Replacing invalid security id with default security id for file 17AE.
corruption found and fixed.
[.............]

Well... good to know! I had errors in my drive and now Windows fixed them! I've went to one of the reported files to double-check and... the file cannot be opened anymore! Explorer also reports the the size is "0 byte" now.
Going around the HDD drive... I've discovered that LOTS of files are now 0-length. What the hell? The log said about "security ids", I can't believe the file is now became "deleted", "corrupted" or something else!

Important note: I confirm that, for most of those 0-length files, they were perfectly accessible before chkdsk.

Has anyone a clue of what is going on? Is it something I can recover? Thank you

 

[fzabkar]

I don't trust Data Lifeguard. Instead, can you retrieve a SMART report with CrystalDiskInfo?

 

[USAFRet]

"I had errors in my drive and now ..."

Before that started, you should have had a good backup.
You ran chkdsk /f ?
The /f is Fix. It attempted to "fix" it.
For various definitions of "fix".

 

[fzabkar]

See the last post in the following thread:

https://www.sevenforums.com/system-security/194742-file-security-permissions-messed-up-chkdsk.html

 

[fzabkar]

There may be a way to undo the damage done by CHKDSK, but the event log must first be saved so that we know which files were affected.

One can view the security ID of any affected file with a disc editor such as DMDE. I would be interested in pursuing this avenue if the OP is amenable.

 

[RolandJS]

Going forward, please begin and maintain routine backups onto external media.