This feature allows disks to be added one at a time to a RAID-Z group, expanding its capacity incrementally. This feature is especially useful for small pools (typically with only one RAID-Z group), where there isn’t sufficient hardware to add capacity by adding a whole new RAID-Z group (typically doubling the number of disks).

FreeBSD’s ZFS implementation comes from the OpenZFS project. This work will be integrated into the OpenZFS repo, with support for FreeBSD and Linux.

The work is functionally complete, and a pull request has been opened.

Remaining work includes some code cleanup, design documentation, addressing test failures.

We also need to solicit code reviewers and respond to code review feedback.

Sponsor: The FreeBSD Foundation