OpenZFS 2.1.3 bugfix brings compatibility with Linux 5.16

It's not just a filesystem, it's an 'open-source storage platform'

The OpenZFS Project has released version 2.1.3 of what the project calls its "open-source storage platform" for Linux and FreeBSD.

The terminology reflects that ZFS is not just a filesystem; it also subsumes the functionality of partitioning and logical volume management. This makes creating and managing what ZFS refers to as "pools" of storage simpler than most of its rivals, such as Btrfs or XFS, which work alongside existing partitioning and LVM tools.

This leads to some overlap. For instance, Btrfs includes its own RAID tools, but so do both the Linux kernel and LVM2. Red Hat is also working on a new storage manager called Stratis, which aims to rival ZFS's functionality.

The latest version resolves multiple issues from July 2021's 2.1.0 release. This included some significant new features, the most notable of which is Parity Declustered RAID or dRAID, which allows [PDF] much faster resilvering of large RAIDZ arrays.

The version number is a little confusing. OpenZFS 2 followed on from version 0.86, and there never was a "version 1," as we described at the time. The current Ubuntu long-term-support release, 20.04, uses OpenZFS 0.8.3.

As the OpenZFS module has to work closely with the Linux kernel, each release is only compatible with certain kernel versions: for example, 2.1.0 supported from kernel 3.10 to 5.13. The new release bumps the upper limit to kernel 5.16.

The main Linux distribution that uses ZFS is Ubuntu, and its next LTS release, 22.04, is due for release on April 27. As such, OpenZFS 2.1.3 comes too late to be included. "Jammy Jellyfish" will use the current long-term kernel, version 5.15. As such, it will almost certainly use OpenZFS 2.1.2, released in December 2021.

Ubuntu is not the only distro to use ZFS, though. It is also supported in Proxmox, a Linux-based hypervisor, as well as NixOS, Void Linux, Arch Linux, and other distros. OpenMediaVault, a Linux-based NAS distro, includes an option to use the Proxmox kernel, which in turn lets it support ZFS too.

The license clash that hinders Linux adoption of OpenZFS does not affect FreeBSD, which uses ZFS as its native filesystem. This also applies to FreeBSD-based products such as the TrueNAS and XigmaNAS operating systems for NAS servers.

It's also supported in OpenSolaris derivatives such as Illumos, DilOS, OmniOS, OpenIndiana, SmartOS, and the Nexenta NAS OS. The original, pre-OpenZFS version remains part of Oracle's own Solaris.

Debian includes it in its contribs repository as source code, meaning that the Dynamic Kernel Module System (or DKMS) must compile it afresh every time the kernel is updated. The other big-name enterprise distros, SUSE and Red Hat, both exclude ZFS on licensing grounds. Sun released it under its CDDL licence, which is incompatible with the Linux kernel's GPL2. Canonical believes that this is an acceptable use; others, like the Software Freedom Conservancy, feel it isn't.

Along with Linux and FreeBSD, there is also OpenZFS on OS X or O3X for Apple's macOS up to 10.15 – and a Windows port too. ®