Adding data disk larger than parity drive

[Netjet1980]

Hello!

I am aware, that generally your parity drives need to be at least as large as your largest data disk.

Here is the thing:

I ordered a 16 TB WD Elements from Amazon, but the nice guys shipped me a 18TB. I am running dual parity with 2x 16TB Exos drives. I just tried to add this to my array, expecting it to just add it (with only 16 TB useable). I am used for this to work with Synology NAS systems, where you can only use as much space as the parity allows, when you then upgrade parity disks the additional space gets allocated. Sadly, unraid doesn't let me do this and expects a parity swap procedure instead.

Before I put my 18TB to the side until I can afford DECENT 18TB parity drives (don't fancy those "internal use" WDs as parity compared to the great performing EXOS drives). Is there really no other way?

[JorgeB]

2 minutes ago, Netjet1980 said:

that generally your parity drives need to be at least as large as your largest data disk.

Always, you can use the new larger drive as parity and the old parity as data.

[Netjet1980]

Just now, JorgeB said:

Always, you can use the new larger drive as parity and the old parity as data.

 

Well I would need to get a second 18TB drive (it's a dual parity system), additionally I am concerned about system performance using a white label internal use WD drives for parity, in my experience they run very hot and don't perform great, it's a WD180EDGZ). 18 TB exos drives on the other hand are stupid expensive at the moment. So I was hoping there was  away to limit the useable drive size from 18 to 16 TB somehow.

[JorgeB]

7 minutes ago, Netjet1980 said:

So I was hoping there was  away to limit the useable drive size from 18 to 16 TB somehow.

The only way would be to use HPA to limit the 18TB disk to 16TB, not all controllers/devices support this, but it won't hurt to try.

[JorgeB]

11 minutes ago, Netjet1980 said:

Well I would need to get a second 18TB drive (it's a dual parity system

And forgot to mention, you don't, the other parity could remain as is, since no data drive would be larger than 16TB.

[itimpi]

13 minutes ago, Netjet1980 said:

Well I would need to get a second 18TB drive (it's a dual parity system), a

There is no requirement in a dual parity system that the parity drives are the same size - just that they cannot be smaller than the largest data drive.

[Netjet1980]

Just now, JorgeB said:

And forgot to mention, you don't, the other parity could remain as is, since no data drive would be larger than 16TB.

That's actually a great point! Might give this a go and see how these shucked 18TB WDs perform as parity.