SMART odd error

ATA Error Count: 1
	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 1 occurred at disk power-on lifetime: 25635 hours (1068 days + 3 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 53 00 ff ff ff 0f  Error: UNC at LBA = 0x0fffffff = 268435455

  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 ff ff ff 4f 00  20d+10:15:07.577  READ FPDMA QUEUED
  60 00 40 ff ff ff 4f 00  20d+10:15:07.577  READ FPDMA QUEUED
  60 00 40 ff ff ff 4f 00  20d+10:15:07.577  READ FPDMA QUEUED
  60 00 40 ff ff ff 4f 00  20d+10:15:07.577  READ FPDMA QUEUED
  60 00 40 ff ff ff 4f 00  20d+10:15:07.577  READ FPDMA QUEUED

^^^^  

I get this odd error message on one of my drive and I UNRAID keeps telling me my drive have an "error".  I try to find a bit more details on that specific SMART log, but I can't find anything obvious.

I reseated all SATA cables, I've been doing a couple power cycles in the last days, the error seems to "stick". I just acknowledge the error in UNRAID gui.

In the past I had experienced other SMART errors and HDD, it always meant the drive was dying: and there was symptoms like slow read or odd errors reported by the OS, etc.

At the moment, I'm clueless because the drive performs well and it does gives any sign of being unreliable.


Drive info:
Seagate BarraCuda 3.5 (CMR)

ST3000DM008-2DM166
Power-on hours: 34122 (3y, 10m, 21d, 18h)
Head-flying hours: 14990h+46m+24.279s