Just recently upgraded to unraid 6 from 5 and immediately saw that one if my disks has 8 pending sectors.

 

Since this is an AF drive I understand that to mean there is 1 4k sector pending to be reallocated.

 

I've run both smart short and long tests and they both pass. I see no errors and there is no LBA of where this bad sector is.

Would like to find that out to see if it was in use and what file might be affected.

 

I've copied all the data off the drive to another machine as a failsafe and again I had no read errors.

 

Anyone have any ideas why if there is indeed a bad sector why the smart reports don't show the LBA.

 

The drive is a HGST 6TB NAS.

 

Any help would be appreciated.

 

Mark

 

I have seen one other case like this, and no, I can't explain it either.  The long test should have stopped on the first pending sector, and reported its LBA.  Sounds like the drive is mostly OK, and the sectors are readable.

 

The only way to clear pending sectors is to write to them.  So what generally has to be done in unRAID is to either rebuild the drive onto itself (forcing a rewrite of every sector with what is already there), or to pull it and Preclear it then rebuild on it or a substitute, or run a non-destructive BadBlocks test on it (using the -n option I believe, which rewrites each sector onto itself).

I've seen this same behavior multiple times on WD disks only, when it happens there's no way to clear the pending sectors, it's like they are false positives, or maybe they were reallocated but SMART not correctly updated.

Thanks, that's good to know.  Bad behavior, but apparently can be ignored!

Thanks for the info guys. I was thinking it was a glitch myself also.

Going to replace it anyway and work on it outside of unraid.

 

A possibility (that I read online so not sure if true) is that its a spare sector that has not been brought into

use but the drive firmware has seen it as potentially bad.

 

May call HGST and see if they have an explanation. Will report back if I find out anything.

 

Mark

 

Edited March 30, 20179 yr by Marky