I've taken my 2-bay Synology offline (planning to sell it) and moved the two drives from it into my unRaid box. After the clearing process, one of them has a reported number of reallocated sectors; from what I've read it is suggestive that the drive may be degrading and is a candidate for replacement. Since I put the drive into the unRaid box the number hasn't changed. I can remove it from the array as there isn't any data on it (and I'm not hurting for the loss of the 3TB). Should I plan to replace the drive? It is a WD Red 3TB with plenty of warranty on it still.

 

The other drive is from the same batch, purchased at the same time, and doesn't have any reported issues.

 

 

All drives in the parity protected are required to be read perfectly from start to finish in order to replace a failed drive, regardless of whether they have data on them or not, so it's in your best interest not to have extra liability in the form of a questionable drive occupying a drive slot.

 

Keep in mind that to remove the drive, you will need to rebuild parity, so make sure all your other drives are in good shape before you start the removal process.

 

As long as the number doesn't change, the drive is probably ok, but like you said, you don't need the space, so no point in taking the risk.

 

If it were my drive, I'd probably keep it for offline backups, no point in going through the hassle of replacing it at this point.

After the parity process, the same drive's Unallocated sector count had risen to 409. Not a complaint from the other drive which is of a similar vintage.

 

I stopped the array and created a new config excluding the problematic drive. Undergoing another parity build now. Will figure out what to do with that one drive after - might pull it out and stick in an enclosure for a separate backup of the essential data.