Multiple bad sectors, but SMART scan reports as healthy

[NotAGolf]

I've got a couple of 6TB WD Reds in a Synology NAS (SHR raid type). A couple of days ago, the NAS started beeping warning that the storage pool was in the degraded state.

After looking at the two drives, one is showing as 'Not Initialized', with a bad sector count of 169 and it had tried (and failed) to re-identify it twice. It doesn't look good, but the weird thing is that when I run a quick SMART scan on it (via Synology), it reports it as healthy. I tried running an extended scan, but it hangs on 90% which after a quick google.

I'm fairly sure the drive is knackered, but as I'm still in the 3 year warranty period, I want to make sure it's knackered before I RMA it to prevent WD rejecting it. What's the best way to test a drive? I've got a 3.5" caddy so can plug it into my laptop.

I'd be tempted to test the other drive while I'm at it too, although this isn't reporting any bad sectors.

 

[NotAGolf]

Quick update in case it helps anyone...

I took the drive out and put it in a caddy and used the WD Data Lifeguard Diagnostic on it. This also passed the quick smart test, but failed the extended test after a couple of minutes with a 'Too many bad sectors' message. Seeing as it's their own software that's reporting the drive as knackered, I should hope I don't have any issues with the RMA.

 

[Lysander]

A slow uptick in bad sectors over a long period of time is, in itself, not a cause for concern. However, 169 of them within three years is quite a lot. That, in itself, says to me the drive has serious problems.