Hey all, I have a fairly big Unraid 6.1.6 system, with 10 disks (3x4TB, 7x2TB). One of my 2TB disks is failing, so I want to replace it. However, the replacement disk I have is another 4TB disk that, the system claims, is bigger than the parity disk. So, it wants to do a parity swap. I'm a little nervous that this might mean some data loss: would the data from the failing 2TB disk be lost in this swap? Is there a swap method to avoid this, or should I buy another 2TB disk, swap that out, rebuild and then replace it with the 4TB?

 

Thanks in advance,

 

Richard

You can do a parity swap, make sure your spare is properly tested with preclear, even so it can a little more dangerous than a normal rebuild, but that’s you’re only option with a bigger disk.

 

Fallow the instructions carefully and unless there’s another disk failure you won’t lose any data.

 

Okay, thanks. That makes sense, but if another drive craps out partway through, then it is game over. Risky. Of course, I am tempting fate with a faulty drive in there, but I don't see the point of tickling a bear if you wake up next to him, as it were.

 

I think what I will do is to get another 2TB, replace it, rebuild and then do the parity swap and keep the 2TB as a spare. That seems less risky.

And after that, it would be wise to investigate why HPA has wound up on your parity drive.

Another option would be to migrate the data off the emulated 2TB drive to the other drives in the array.  Once all that data has been cleared off the emulated drive, restart the array with a new configuration with the failed drive removed and the parity slot replaced with the new 4tb drive.  It will then startup rebuilding the parity on the new 4tb drive.

Okay, thanks. That makes sense, but if another drive craps out partway through, then it is game over. Risky.

 

Note that during a normal rebuild you will also be in trouble if another disk fails, the added risk in a parity swap is that you'll be using a new drive for parity (why it's important to use a precleared and well tested disk) and since the rebuild will erase the old parity you'll be in trouble if the new untested disk fails during the rebuild.