This is less of a feature request and more of a "what are the odds that this ever happens", but here goes: I'm sure plenty of unRAID users love the ability to upgrade drive slots piecemeal, and run an array with multiple different drive sizes. Is there any chance of that being supported in ZFS at some point?

 

If not, could unRAID work around that with a solution like in this example:

• Say you have a 4TB, a 6TB, an 8TB, a 12TB, and 3 16TB drives, and you want 2-drive parity
• So you create a 4TB partition on each drive, then a 2TB drive on the 6TB-and-up ones, another 2TB on the 8+s, a 4TB on the 12+s, and another 4TB on each of the 16s
• You combine each set of partitions into a raidz2 vdev (of which you have 5 total, one for each partition on the largest drives), all within a single zpool

 

I've seen this approach discussed in a few places before, and a lot of people seem to reflexively reject it, but I'm not entirely sure why? There'd certainly be a lot of complexity in the management/UI tooling for this, but I don't think any of the problems are unsurmountable. In theory, it could allow for all the benefits of ZFS while still retaining the upgrade-friendliness of classic unRAID.

6 hours ago, rcombs said:

and run an array with multiple different drive sizes. Is there any chance of that being supported in ZFS at some point?

For the array you already can do this with zfs formatted disks.

On 7/21/2024 at 1:35 AM, JorgeB said:

For the array you already can do this with zfs formatted disks.

Sure, but that's individual drives in an unRAID array, not a RAIDZ setup. It's a reasonable choice for some people, certainly, but it doesn't give the benefits of RAIDZ (self-healing, striping performance, etc). I want to have my cake and eat it too.

You'd likely lose any performance benefit from striping from multiple things being on the same drive and requiring seeking... seeking's by far the most "expensive" thing on spinners. Not to mention having to carefully set things up so you don't lose multiple redundancies when a drive fails and degrades multiple vdevs.

Edited July 30, 20241 yr by Kilrah

4 hours ago, rcombs said:

not a RAIDZ setup

That is a zfs limitation, LT cannot do anything about that.

On 7/30/2024 at 10:46 AM, rcombs said:

Sure, but that's individual drives in an unRAID array, not a RAIDZ setup. It's a reasonable choice for some people, certainly, but it doesn't give the benefits of RAIDZ (self-healing, striping performance, etc). I want to have my cake and eat it too.

Then configure your ZFS pools manually. I did have on my previous setup a raidz1 of several drives, one of which was not the same size (2tb larger, so 3x8TB and 1x10TB, all added as raidz1). You have to do so on the command line, using the "force" option, as otherwise, basic checks tell you you can't create the zpool

If you want to mix and match drives with different sizes, you can do so on the unraid main array...

So asking for something else at this stage, given that you can do what you want with a little effort, is asking "too much". It is in no way "reasonable". When and if ZFS supports mixed sized drives, I'm sure we'll get that built-in too.