AnyRaid with RaidZ?

[jxdking]

Recently, I came across a podcast regarding a new ZFS AnyRaid pull request. May 2025 OpenZFS Leadership Meeting
AnyRaid, I think, would be a very attractive feature to have for consumer market. However, it seems to only support mirror for now. I don't think mirror is the best way to approach to "AnyRaid". I am not anywhere familiar with RaidZ source code. My speculation below may be just wrong.

If I am not wrong, the stripe size of raidz does not have to be exactly vdev width minus redundancy. The stripe size could be less than that. Let's say we have raidz1 with 5 drives. The valid stripe size could be 4, or less. When the stripe size is less than 4, you loose space efficiency. Considering you got 0 efficiency without AnyRaid with mixed-up drives beyond the smallest drive, it is not bad.
I think there should be a way to let raidz to utilize mixed-up drives. For example, as long as there are 2 drives that still not full, the vdev should still be able to maintain raidz1 with smaller stripe size.

[tonyhutter]

"With ZFS AnyRaid, we will see at least two new layouts added: AnyRaid-Mirror and AnyRaid-Z1. The AnyRaid-Mirror feature will come first, and will allow users to have a pool of more than two disks of varying sizes while ensuring all data is written to two different disks. The AnyRaid-Z1 feature will apply the same concepts of ZFS RAID-Z1, but while supporting mixed size disks."

https://hexos.com/blog/introducing-zfs-anyraid-sponsored-by-eshtek

[jxdking]

It is good to know.
I am still surprised at the fact that the Mirror implementation will come first. In the meeting, they are talking about cropping drive spaces into 64GB chunks and mirror on them. It is rather cumbersome comparing to raidz1 would implement.