So I don’t know if this is something that I missed entirely in the documentation, but a while back, one of the drives in my NAS gave up on life and decided to stop working. Being the lazy person I am, and relying on the uber redundancy of RAID6, I left it for a few weeks (including the time after I purchased a replacement drive). In my defence, I lost the key to the drive trays and had to wait until a friend of mine could find me one. (To skip my long winded path to the end solution, just jump to the last paragraph)

In any case, today I swapped in the replacement and in an anti-climactic fashion, nothing happened. In fact, it didn’t even pick up the new drive. I feared that the NAS itself was dead and I would have to go through the painful process of getting a replacement and everything. None the less, I decided to would take a chance and reboot the unit. Luckily, this did the trick and while it still didn’t automatically rebuild the array, it now detected the new drive.

Checking the RAID configuration page, the only available option was to assign the new drive as a spare.

After some digging on the Thecus Forums, the only mention I found was indirectly through another person’s troubleshooting post where he mentions that setting the drive as a spare fixed his issue.

I was hoping to get some solid information that would support this, but I figured I had nothing to lose and at the very least, I’d have a RAID5 array with a hot spare to back me up.

9 hours later, I’m back up and running, and the RAID 6 array is healthy once again. It would have been nice if Thecus had some better documentation available, but I suppose piggybacking on a forum is better than nothing.

In short, if a drive in your RAID array fails, and if after replacing the drive it doesn’t automatically rebuild, just go into the RAID configuration screen and set it as a spare and the NAS will start rebuilding the array at that point.