Hello all,

I'm still working on parity swapping either way, but my parity disk has a few errors that happened during parity checks. I would usually be concerned about UNC at LBA errors, but this one seems very strange and doesn't make much sense. Any idea what could cause this? Note that I have a backplane so it's likely unrelated to cables as none of my other drives have this issue.

ATA Error Count: 2
	CR = Command Register [HEX]
	FR = Features Register [HEX]
	SC = Sector Count Register [HEX]
	SN = Sector Number Register [HEX]
	CL = Cylinder Low Register [HEX]
	CH = Cylinder High Register [HEX]
	DH = Device/Head Register [HEX]
	DC = Device Command Register [HEX]
	ER = Error register [HEX]
	ST = Status register [HEX]
Powered_Up_Time is measured from power on, and printed as
DDd+hh:mm:SS.sss where DD=days, hh=hours, mm=minutes,
SS=sec, and sss=millisec. It "wraps" after 49.710 days.

Error 2 occurred at disk power-on lifetime: 31278 hours (1303 days + 6 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
  -- -- -- -- -- -- --
  40 43 00 00 00 00 00  Error: UNC at LBA = 0x00000000 = 0

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  60 00 10 58 4f 86 40 00   7d+13:54:49.902  READ FPDMA QUEUED
  60 00 38 58 63 86 40 00   7d+13:54:47.291  READ FPDMA QUEUED
  60 00 30 58 5f 86 40 00   7d+13:54:47.290  READ FPDMA QUEUED
  60 00 28 58 5b 86 40 00   7d+13:54:47.289  READ FPDMA QUEUED
  60 00 20 58 57 86 40 00   7d+13:54:47.288  READ FPDMA QUEUED

Error 1 occurred at disk power-on lifetime: 30706 hours (1279 days + 10 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
  -- -- -- -- -- -- --
  40 43 00 00 00 00 00  Error: UNC at LBA = 0x00000000 = 0

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  60 00 00 70 3c 1c 40 00  31d+23:15:25.360  READ FPDMA QUEUED
  60 00 00 70 38 1c 40 00  31d+23:15:22.785  READ FPDMA QUEUED
  60 00 00 70 34 1c 40 00  31d+23:15:22.779  READ FPDMA QUEUED
  60 00 00 70 34 1c 40 00  31d+23:15:22.779  READ FPDMA QUEUED
  60 00 00 70 30 1c 40 00  31d+23:15:22.775  READ FPDMA QUEUED

Should I be concerned about this? I wanted to use this disk as an array after parity swap, but won't if this is concerning. I have diagnostics that I can attach if desired, although the above seems to be the root of the issue.

Please post the diagnostics

Just now, JorgeB said:

Please post the diagnostics

Here you go:

Edited October 7, 2025Oct 7 by tekcor
remove diag

It's logged as a disk problem, the UNC @ LBA 0 is strange, like you mentioned, but I've seen it before. Maybe a firmware issue?

I would recommend running an extended SMART test on that disk.