Defraggler shows some disk blocks as occupied (blue) but with no filename

[martinu]

Version V2.22.995 (64-bit)

I've noticed recently that on several NTFS drives on my Windows 7 Home Premium PC, there are blocks which are shown as being allocated on the map but which do not display an associated filename if I left-click on a block or mouse over the block. The presence of the blocks still prevents a file from being defragmented to use them, but they cannot be moved to the end of the disk or any other operation. Contrast "No files in this block.png" and "1 file in this block.png". The files showed up previously when I clicked on then, but after moving a few other files, they became "orphaned".

I've been using the same version of Defraggler (the latest) since long before the problem was first noticed. Rebooting (to force a dismount/remount) does not cure the problem. I've seen it both with SATA drives and with external USB drives (which probably have USB-to-SATA converters internally). I've seen it on drives with plenty of disk space (eg the C drive that has about 50% free).

Moving folders to another drive does actually remove the "stuck blocks", so they really are being used by files (they are not orphaned) but the stuck blocks return (though not in the same place) if I copy the folder back again.

I've used Defraggler for many years (both doing full and freespace defragging) but I've only noticed this symptom in the last few months.

Is this a known problem?

 

Edited May 13, 2020 by martinu
adding extra info