Noob question, apologies in advance.

I am considering migrating my current array (28 data disks + 2 parity) to a zfs pool. Logistics of the data transfer aside, I have been trying to figure out how to organize the pool. My first thoughts were to group the drives by capacity, so my mixture of 8tb, 10tb, and 12tb drives would compose vdevs within the pool.
I am working with 17x8TB disks, 5x10tb disks, and 8x12tb disks. My first thought was for 3 vdevs using the 8tb disks (raidz1, 5 disks each, 2 cold spares or a 5/6/6 grouping), one raidz1 vdev of the five 10tb disks, and a raidz2 with all 8 of the 12tb disks.
What I don't know (and can't find good info on) is if the vdevs within the same pool can have these varying disk amounts and raidz topologies.
Can anyone offer a suggestion?

5 hours ago, JamesHaefner said:

What I don't know (and can't find good info on) is if the vdevs within the same pool can have these varying disk amounts and raidz topologies.

While this is supported by zfs, though not recommended, it's not supported by Unraid.

thanks for the info, I did a bit more digging (and AI chatting), and was getting to that conclusion as well.
I have been thinking of my pool layout options, and I am thinking of these two approaches:

Option 1 - 6-disk vdevs

Vdev	Drives	RAIDZ	Notes	Usable
1	6×8TB	RAIDZ1	uniform	40 TB
2	6×8TB	RAIDZ1	uniform	40 TB
3	6×12TB	RAIDZ1	uniform	60 TB
4	5×8TB + 1×10TB	RAIDZ1	mixed, smallest=8	(6−1)×8 = 40 TB
5	4×10TB + 2×12TB	RAIDZ1	mixed, smallest=10	(6−1)×10 = 50 TB

Total starting usable: 40 + 40 + 60 + 40 + 50 = 230 TB

Option 2 - 5-disk vdevs

Vdev	Drives	RAIDZ	Notes	Usable
1	5×8TB	RAIDZ1	uniform	32 TB
2	5×8TB	RAIDZ1	uniform	32 TB
3	5×8TB	RAIDZ1	uniform	32 TB
4	5×10TB	RAIDZ1	uniform	40 TB
5	5×12TB	RAIDZ1	uniform	48 TB
6	2×8TB + 3×12TB	RAIDZ1	mixed, smallest=8	32 TB

Total starting usable: 32 + 32 + 32 + 40 + 48 + 32 = 216 TB
I have been thinking about my drive upgrade path, since with zfs I can't just follow the typical unraid approach of adding a few drives as a time.
As long as Unraid ZFS supports mixed drive capacities within a vdev the way that I am thinking, Option 2 above gives me an upgrade path of replacing 2 disks in vdev6 to gain pool storage before adding a whole new vdev or upgrading a whole vdev, whereas Option 1 requires 4 or 5 drive upgrades, at the cost of starting initial pool storage.
Can anyone recommend a different vdev layout?

1 hour ago, JamesHaefner said:

since with zfs I can't just follow the typical unraid approach of adding a few drives as a time

ZFS RAIDZ can now be expanded, but the GUI currently only supports that for single vdev pools, multi-vdev pools can be expanded manually, though all vdevs must be expanded before the pool can be reimported by Unraid. More info here: https://forums.unraid.net/topic/46802-faq-for-unraid-v6/page/4/#findComment-1537164

1 hour ago, JamesHaefner said:

As long as Unraid ZFS supports mixed drive capacities within a vdev the way that I am thinking

This is not a problem.

1 hour ago, JorgeB said:

ZFS RAIDZ can now be expanded, but the GUI currently only supports that for single vdev pools, multi-vdev pools can be expanded manually, though all vdevs must be expanded before the pool can be reimported by Unraid. More info here: https://forums.unraid.net/topic/46802-faq-for-unraid-v6/page/4/#findComment-1537164

This is not a problem.

That is what originally pushed me to finally explore zfs for my array, but my different drive sizes currently makes it a bit complicated. for vdev creation.
Do you have any suggestions for a better way to approach this?

With those disks I would probably create 2 RAIDZ2 vdevs with 15 disks each:

15 x 8TB + the remaining disks on another one, this would be around 208TB initially (without the overhead), but once you could replace the two 8TB disks in the second vdev, it would expand to around 234TB

15 wide is a little over what people usually recommend, but in my experience, it still performs great, I have a couple of RAIDZ2 pools that are 24 wide, and still perform great, and for redundancy, I would much rather have a 15-disk RAIDZ2 VDEV than 5 or 6-disk RAIDZ1 VDEVs, especially with those capacity disks.

would 3 10-wide vdevs be a better scenario? I know I would have a full 10x8TB vdev, then 2 mixed ones (7x8TB + 3x10TB, 2x10TB + 8x12TB), but then my upgrade path could be to expand the 10/12TB vdev to all 12TB drives, then slowly upgrade/replace the 8TBs in the mixed 8/10 vdev to either all 10TBs or larger, starting with the 2 drives from the 10/12 vdev...
My current hangup is also my migration path/method, since my existing array has about 208TB on it in the current unraid configuration (258TB usable). So a starting zfs configuration would need to handle my current data before I can consider any drive upgrades

4 hours ago, JamesHaefner said:

would 3 10-wide vdevs be a better scenario?

It's also a good option, with a little less space, but better redundancy and more IOPS due to the extra VDEV, If that's important to you, sequential read/writes should be about the same.