[cgeier]

This is huge news for ZFS users (probably mostly those in the hobbyist/home use space, but still). raidz expansion has been one of the most requested features for years.

[jfreax]

I'm not yet familiar with zfs and couldn't find it in the release note: Does expansion only works with disk of the same size? Or is adding are bigger/smaller disks possible or do all disk need to have the same size?

[ryao]

You can use different sized disks, but RAID-Z will truncate the space it uses to the lowest common denominator. If you increase the lowest common denominator, RAID-Z should auto-expand to use the additional space. All parity RAID technologies truncate members to the lowest common denominator, rather than just ZFS.

[shiroiushi]

As far as I understand, ZFS doesn't work at all with disks of differing sizes (in the same array). So if you try it, it just finds the size of the smallest disk, and uses that for all disks. So if you put an 8TB drive in an array with a bunch of 10TB drives, they'll all be treated as 8TB drives, and the extra 2TB will be ignored on those disks.

However, if you replace the smallest disk with a new, larger drive, and resilver, then it'll now use the new smallest disk as the baseline, and use that extra space on the other drives.

(Someone please correct me if I'm wrong.)

[chasil]

IIRC, you could always replace drives in a raidset with larger devices. When the last drive is replaced, then the new space is recognized.

This new operation seems somewhat more sophisticated.

[zelcon]

You need to buy the same exact drive with the same capacity and speed. Your raidz vdev be as small and as slow as your smallest and slowest drive.

btrfs and the new bcachefs can do RAID with mixed drives, but I can’t trust either of them with my data yet.