OK then. UNRAID 7.01, using Unassigned Devices Plug-in by Limetech dated 2025-11-18. Running Jellyfin 10.10.7 with no issues.

Doing some backup of files the last couple days, and getting a weird error.

Picked up a TerraMaster DR-310 a few weeks ago, and it is working fine. Picked up a TerraMaster D2-320 the other day, as it is listed on the TM site as compatible with larger disks. I also have 12 drives that I'm copying/organizing, so it helps with the process.

Plugged a new formatted WD 24 Red into the TM D2-320. Plugged the TM into the UNRAID USB port, and mounted the drive. Set up Krusader to copy about 5TB of files last night to the "unassigned" D2-320. I assumed it would finish, but it stopped at some point with 90% of files copied, and Krusader froze up. UNRAID froze up. This am I rebooted UNRAID, opened Krusader, and about half of the 20 directories had NO data in subdirectories. Nothing. Hmmm. That never happened before.

Pulled the 24TBHD from the enclosure, and installed onto my main computer SATA bus, and finished copying the missing files. Tested some of the MKV files (via VLC) copied by Krusader, as well as some I copied via the SATA bus. All played fine.

Pulled the 24TB drive from the SATA bus, installed it back into the D2-320. Plugged the D2-320 into my air-gapped computer's (no inet connection) 3.2 USB. Tried copying files, and...,

got the old "The file name you specified is not valid or too long. Specify a different file name.". WTH??? I've seen this error in decades past, but this is not that issue.

The filename is NOT too long. Just for grins I named a couple of the thousands of files to "fred" or "bob" .mkv and tried copying - same message.

I then tried playing the files with VLC - no problem. Both files' sources (UNRAID Unassigned Devices" and SATA bus) files play fine. ???

Went back to my master files on the main computer, and copied via USB 3.2 to the D2-310 with the same 24TB HD. Plugged the D2-320 into the air-gapped computer... and all THE SAME FILES copy fine. And still play fine in VLC.

So... I am guessing that UNRAID has not been completely successful in maintaining the NTFS file structure from XFS to NTFS - at least not with the D2-320 plugged in. That said... I have done this (using Unassigned devices drives in the UNRAID USB port to xfer other files to NTFS machines) with zero problems. Granted not 5TB worth, but at least several hundred GB, and also with much smaller USB sticks and WD USB drives.

Thoughts? I can do a work-around pretty easy - either the SATA connection or SMB from Windows to shares, but... something weird is going on .... And that 4TB that actually copied via the UD Plugin is useless. Glad I started to copy these files before I had 30TB of useless data on several drives. Tried looking for a Windows based "file structure check" program, but could not find anything.

Appreciate comments - and maybe how to fix the files that File Explorer cannot read???

Are you using an Administrator account in Windows?

Hm. Good question. Occasionally I will need to log in as admin for a not-too-often occurring task - like to write to a folder in Program Files. But I did not login as admin for any of these efforts.

But this worked previously - with different drives - not a DAS. I just confirmed that it works - meaning the files can be read on another computer - using UNRAID UD to mount both a 1TB thumb drive as well as a 4TB WD un-powered HD.

I also confirmed that BOTH the DAS's I have exhibit the same problem.

It appears that for whatever reason... the TerraMaster DAS's (D2-310 and D2-320) don't play well as UD in UNRAID 7.01.

At this point I have wiped the files-that-can't-be-copied from the 24TB drive, and will stick it on the SATA network in my main computer, and use SMB to transfer from UNRAID overnight.

What a pita.☹️ But this could have been worse...

I could have connected my new 4-Bay NAS (for off-site archiving) to the UD, and spent days filling it up. Then months or years later when I needed a file, THEN discovered that NONE of the files can be written to another device. That would have been a bad day... It's just so weird that the files will play, but can't be copied... Hm. This almost sounds like a back-door copy-protection scheme.

Investigate permissions on the problem files

OK then. Problem solved after 2 days and a 32 page AI chat.
Short version: Turns out (assuming that the AI engine is correct) there is a known bug in Linux/Unraid:
MFT metadata mismatch created by the NTFS-3G driver in Unassigned Devices (UD).
Although I had previously (and successfully) used 2TB NTFS drives connected to Unraid via USB/Unassigned devices, the same actions now creates this fatal error.

AI indicated that a reason might be because of a W11 update between "then" (maybe 6 months ago) and now..

So. Short version solutions:

1. Format your transfer drive under ExFAT (not NTFS) under W11, then attach to Unraid via Unassigned Devices. I used a 2TB drive and connected via the Unraid USB. I asked, and the AI engine confirmed that this should also work if connecting a HD directly to the SATA cables in the Unraid Server. In my 2TB/USB test, I was able to successfully copy files to the transfer drive, then unmount from Unraid, then connect to a W11 drive via USB, then copy files to NTFS drives.

2. If you already have several TB of data on NTFS drives that cannot be copied (like me), then there is a better solution. DL and install "TeraCopy" to your W11 machine, connect the formerly "Unassigned Device" drive via either USB or SATA, then copy the files to your NTFS formatted devices. It works! I also tested the "copied" file by copying it to another NTFS drive via File Explorer. It also works. The AI engine recommended TeraCopy, after trying several other solutions to identify the problem. It seems TeraCopy does not read the same file errors that Unraid created, and that causes File Explorer to choke.

3. TeraCopy works because it does not read the fil the same way as File Explore. I have used it occasionally in the past; but this program now saves me tend of hours of additional file transfers. Just purchased their Pro version for $29.95. best $ ever spent. And no, I have no financial interest in the company.

If anyone is interested, I made a link to the chat, as well as a copy of same in PDF. Mods - please advise if it is ok - or verboten - to post either.
Never having used AI for almost anything - let alone trying to figure out arcane file structure errors in transferring files between different operating systems - I found the interchange... fascinating.🤨
Not a far-removed interaction from Spock asking the computer to plot a course through the asteroid belt... 😃