Attaching the diagnostic log.

Please don't worry about the missing disk 2. This has intentionally be removed for now.

What's weird is that I have a disk slotted in (16TB), which is not being picked up by Unraid. If I boot with the disk, Unraid doesn't even boot up. If I plugin the disk after Unraid boots, it doesn't show up / identify.

Does the diagnostic provide any indication what's going on?

tower-diagnostics-20260205-0801.zip

Can you see the disk in BIOS?

Which controller is the disk plugged in to?

I am running Unraid headless and cannot access the Bios.

I can attach the disk via usb and can see it.

The issue is not the sata slot though as other disks can be identified though.

Maybe the answer is as easy that the disk is "faulty", but wondering whether there is some easy to way to figure this out?

1 minute ago, trurl said:

Which controller is the disk plugged in to?

The same as disk 1 (ZXA0Z649)

The controller on the motherboard?

What about power? You have a lot of disks.

Some disks are on mobo and others are with a controller card. I forgot where this disk is connected to, but it's the same as disk 1.

Power should be more than sufficient with a 1650W PSU.

Edited February 5Feb 5 by steve1977

It must be somewhat related to either the disk or to Unraid / settings.

I just swapped again the UD and the mobo disk. And all works well. The previously unidentified disk is now UD. I even mounted it. Including diagnostics.

tower-diagnostics-20260205-0912.zip

46 minutes ago, steve1977 said:

I forgot where this disk is connected to, but it's the same as disk 1.

disk1 is using motherboard controller.

23 minutes ago, steve1977 said:

The previously unidentified disk is now UD.

So it works in an external USB enclosure then?

Sounds like the 3.3V problem.

What happens if you plug it in to one of your controllers, but power it with a MOLEX-SATA adapter?

Yes, the disk works in an external USB enclosure.

Other disks work though in the same disk slot. In the new diagnostic, I plugged in an 28TB disk instead, which is well identified and works well.

So, the 16TB disk only works in USB enclosure, but not when attached to the mobo. The 28TB disk works both in USB enclosure and also when attached to the mobo (same slot).

15 minutes ago, trurl said:

Sounds like the 3.3V problem.

What happens if you plug it in to one of your controllers, but power it with a MOLEX-SATA adapter?

17 minutes ago, trurl said:

3.3V problem

https://www.instructables.com/How-to-Fix-the-33V-Pin-Issue-in-White-Label-Disks-/

Oh... Thank you. This is quite likely to explain it. Don't think I have such an adapter, but can look into. Before doing this, maybe worth trying to connect it to a different slot? Either to a controller card rather than mobo. Or a different psu psu rail. It works when in an usb enclosure, so maybe there is a way to also get it to work without adapter. I also need to check, but I believe I have another identical 16TB disk that is working. Disk 3 or disk 4 should be the same disk and is also connected to the mobo? Maybe I swap this disk to see whether this works, which may help to narrow the issue.

44 minutes ago, steve1977 said:

another identical 16TB disk that is working

Possibly that one is already on a MOLEX connector. If you have a lot of disks, PSU may not have enough SATA cables to go around so MOLEX-SATA is often used out of necessity.

Let me check this out once back home. Thanks for your help!

I cannot rule it out, but I don't think it is the 3.3V issue. I have other disks (same model), which don't face the issue. I also tried to use the "unidentified" disk in other slots, but without success either.

I mounted the "unidentified" disk as UD (which works). I ran an "extended smart" check, but it doesn't complete (stuck at 10%).

Also noticed an "UDMA CRC error count", but remember seeing somewhere that this should typically not be an issue? See more details below.

Any other ideas what I can try?

Error 54 occurred at disk power-on lifetime: 24570 hours (1023 days + 18 hours)
  When the command that caused the error occurred, the device was active or idle.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  84 53 00 00 00 00 00  Error: ABRT

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  b0 d5 07 04 4f c2 00 00      03:29:56.984  SMART READ LOG
  b0 d5 01 04 4f c2 00 00      03:29:56.945  SMART READ LOG
  b0 d5 01 09 4f c2 00 00      03:29:56.942  SMART READ LOG
  b0 d5 01 06 4f c2 00 00      03:29:56.940  SMART READ LOG
  b0 d5 01 01 4f c2 00 00      03:29:56.937  SMART READ LOG

1 hour ago, steve1977 said:

I ran an "extended smart" check, but it doesn't complete (stuck at 10%)

It only updates the completion amount every 10%, so probably not stuck. 16TB will take more than an hour or two for each 10%.

UDMA CRC is problems with the connection. If it isn't increasing it's OK.

1 hour ago, steve1977 said:

I mounted the "unidentified" disk as UD (which works)

Because in enclosure that takes care of 3.3V

1 hour ago, steve1977 said:

don't think it is the 3.3V issue

Did you do this?

23 hours ago, trurl said:

power it with a MOLEX-SATA adapter

Thanks for your help. I replaced the disk and now things are working.