Questions about handing drive failures

[sirjorj]

I currently have a QNAP NAS that is about 6 years old. I am planning on upgrading sometime in the near future and a FreeNAS box is my top choice.

Yesterday one of the drives failed. I popped in the spare drive and have the array rebuilding now, but I did see that another drive is indicating that it may be on its last legs. The 'near future' may be sooner than I had hoped.

A while back I got a A1SAI-2750F SuperMicro board and have it running with 32G ECC RAM. This board will most likely run my new NAS. I have been testing this board to see how capable it is, and overall I am impressed. Only potential issue is that the internal USB port is USB3 and FreeNAS doesn't like that.

I want a rackmount case with hot swappable drive bays, and so far, this is my top choice: http://www.norcotek.com/item_detail.php?categoryid=1&modelno=RPC-2208#

My big question is this: If a drive fails, how do I know which drive failed? With my QNAP box, a red error light flashes on the case and when you load up the config page, you can see which drive is bad (Drive 1, Drive 3, etc...) so you know which one to replace. How does FreeNAS handle this? Can you alias drives like that? Or do I have to remember which serial number is in which drive bay? Or can it flash the lights of the bad drive? Or, worst case scenario, what happens if a drive fails on a pool with 1 drive redundancy and I pull the wrong drive by accident. Did I just lose everything?

 

[Robert Trevellyan]

My big question is this: If a drive fails, how do I know which drive failed?

Best practice is to label the physical drives with their serial numbers (or at least the last few characters). Then you have to match the gptid with the serial number, which you can do using @Bidule0hm 's script. There might be ways to use the hard drive lights that I'm unaware of.

Or, worst case scenario, what happens if a drive fails on a pool with 1 drive redundancy and I pull the wrong drive by accident. Did I just lose everything?

If you have a drive failure in a RAIDZ1 pool and you pull the wrong drive, the pool will become unavailable. However, when you put the wrongly pulled drive back, FreeNAS should recover cleanly. A better strategy is to use RAIDZ2 pools so that a single drive failure doesn't leave you in such a precarious position.

 

[sirjorj]

Thanks for the reply.
Does FreeNAS allow you to designate a drive that should stay off until another drive fails?
Say I put 6x WD Red 4TB drives in. Can I allocate 5 of them in a RAIDz2 (for ~12TB storage + 2drive redundancy) and set one as the replacement drive so if a drive fails, that 6th one will replace it on the fly?
I think I read that ZFS supports this - I'm just wondering if FreeNAS has it surfaces in a convenient way.

 

[danb35]

What you're talking about is a hot spare. FreeNAS 9.3 is said to support them as of a couple of months ago, but I don't know how robust that is.

 

[Ericloewe]

Hot spares seem to be working now. RAIDZ3 makes more sense than RAIDZ2 + Hot Spare, though.