Nonexistent *.ffs_db files created on distant NAS drive

[HansHans]

I have a few files with the extension .ffs_db , created on a distant NAS drive, which make problems.
The NAS runs a SMB Server to organize data handling. I'm using FreeFileSync on a Windows Pro 64 bit verions 10.0.19045 Build 19045 PC, running the FreeFileSync version 12.0.
It was the same with the previous FFS version.

These problematic files are
> recognized by FreeFileSync
> have no file attributs as FreeFileSync claims
> generate error messages from FreeFileSync
> as it cannot be deleted by FreeFileSync
> as the files are not found by FreeFileSync
> listed by the file explorer,
> cannot be deleted with Windows tools as well
> have zero size in the FileExplorer
> have no date in the FileExplorer
> are claimed to be non existent by the file explorer
> same results using the "del" command in the Windows CMD window.

So it seems FreeFileSync has started deleting this file, but the process was truncated somehow, leaving behind an entry in the filesystem without completing the process.

[xCSxXenon]

Run chkdsk, or whatever the equivalent is for your NAS, on that storage volume, restart NAS
Usually this scenario is caused by a corrupted file table/system

[HansHans]

I'm confident, Your are right, the file table is corrupted.
The question is: *How* did this happen.

That are exclusively exactly these .ffs_db files. Never another one. And this problem occurs exclusively on the distant system, never on the local one. It happens rarely, but repeatedly, from time to time. Weeks in between. If I work distantly with the NAS, copy files etc. I didn't observe anything like that.

But on the other side, I trust that FFS cannot have any lowlevel access to the drive, so it must be something on the NAS side ... I have no idea, why this only happens with FFS


>>Usually this scenario is caused by a corrupted file table/system<<