Add a vdev with different amount of drives to an existing ZFS Pool

[Lilly]

Hello,

I have a ZFS Pool with a single vdev made out of 3x8TB drives in raidz1.

Now, I have an additional 4 drives that I'd like to add to that existing pool as a new vdev, also in raidz1.

 

After my first search, I found this post by a moderator about adding additional vdevs and how they have to be the same width (amount of disks):

However, this info is wrong: After reading up some more I found contradicting info, and upon trying it myself, it worked perfectly fine when doing it manually in the terminal. The pool mounts perfectly fine, too.

So I know ZFS can do this, and I tested around and also already managed to add the separate vdev to the pool using terminal:

 

The issue now is, that the Unraid Web UI only lets me select "1 group of 7 devices" when I try to mount the pool like this - and it ends up saying the pool isn't mountable.

 

Is there any way to work around this or is it planned to add this functionality (maybe in 6.13)? This pool I used for testing isn't my primary pool, but I'd love to add the 3x8TB HDDs to my main pool (which currently is made out of 5 disks) and it's kind of frustrating to be stopped by an Unraid limitation when the underlying file system clearly can do the job

Edited May 13 by Lilly

[JorgeB]

10 hours ago, Lilly said:

However, this info is wrong

I can see how you got that from the way I wrote it, but what I meant was, adding a single disk to a raidz volume, which is what the user was trying to do, is not supported by zfs, at least for now, and to expand the pool with Unraid he would need to use a vdev of the same width, which is the only option Unraid supports, I'm going to edit that post to make it clearer, in case someone else finds it in a search.

 

As for your question, Unraid does not support vdevs with different widths, it also doesn't support vdevs using different profiles, e.g., one mirror, and one raidz, one raidz1 and one raidz2, etc, this is also supported by zfs, though not usually recommended, AFAIK there are no plans to support either in the near future, but you can always make a feature request.

[Lilly]

Ah, yeah, in that case I misunderstood what you said in the other post, thanks for the clarification!

 

I do plan to stay with the same type of vdev inside of a given pool, but being able to set at least different vdev widths would honestly be great. ZFS is already pretty inflexible as-is, and this would at least give a decent amount more flexibility when it comes to expanding a pool. I'll create a feature request later today, thank you.