I've googled and searched the boards but I cant find any solution. I'm running the free version of unRAID. I had 2 x 2TB drives which I was running in an unprotected array for a while till I got the hang of the various features. Eventually I decided that I should add a parity drive and got hold of another 2TB drive that I was using in a Windows machine. I pre-cleared the drive and then stopped the array and assigned it to the parity slot. But I get the error "Disk in parity slot is not the biggest". Well it isn't the biggest, but it is definitely the same advertised size as the other 2, ie 2TB. It also suggests that I try parity swap. I'm not sure what this is, and again googling didn't point me to anyone trying this in a situation similar to mine. Could someone identify what is going on here? Thanks.

Post a syslog. Without it, you are only going to get guesses as to the cause.

 

My guess is that you are running a gigabyte motherboard in one of your systems, and it added HPA to the drive. 2TB drives should all be exactly the same size to the last byte, so when you say it isn't the biggest, that indicates an issue with that drive, and if your unraid box has a gigabyte board, it's a very serious issue that will probably cause you to lose data in the future.

I've attached the syslog

syslog.zip

I was right.

Dec  7 21:13:52 NAS kernel: ata1.00: HPA detected: current 3907027055, native 3907029168

Search the forum for HPA removal.

Cool. Thanks a heap!

Ok, I got a "HPA removed" message after following the procedure. Should I reboot now and try to re-add the drive as parity?

 

EDIT: I rebooted, and the parity drive has been successfully added. 

I now see parity sync progress at the bottom. Truly appreciate the help!

Do you know how the HPA got on the drive? Not think possibly how it might have happened, but know for sure? If you don't know for sure, your data could be in jeopardy if the HPA is put back on to a valid array drive.

Well, that hard drive has been in and out of a lot of PCs, media players, Dunes etc. so it's hard for me to say.

 

But I have been using the unprotected array of the other two 2TB hard drives for almost a year now without any hiccups. And does the syslog say anything about whether there is HPA on the other 2 drives?