Here at TrueNAS, we’re excited to be at the forefront of OpenZFS development, leveraging OpenZFS as the foundation for our data management layer, and are proud to be the deployment vehicle for the majority of OpenZFS storage systems in use today. We’re excited to share the latest improvements in OpenZFS, with the release of OpenZFS version 2.3.0 on January 13, 2025. This new version of OpenZFS is being integrated into the next TrueNAS release, TrueNAS 25.04 (Fangtooth).

The TrueNAS Engineering team has made significant contributions to OpenZFS 2.3.0, with a pre-release version of OpenZFS 2.3 integrated into TrueNAS 24.10 (Electric Eel). This version has performed well and stood up to the standard of reliability set by OpenZFS. Customers can use Electric Eel today if they want several of these OpenZFS 2.3 features and the stability it offers.

The current development version of TrueNAS, Fangtooth, aligns with the OpenZFS 2.3.0 release. Fangtooth will use this version of OpenZFS throughout its version lifecycle. This blog outlines the current status of the full set of OpenZFS features in the upcoming release.

Fast Dedupe Delivers Good Performance

Deduplication is highly desirable for many workloads, including virtualization and several file storage use cases. Where there is naturally a high ratio of redundant data within a pool, deduplication effectively increases not only the usable capacity of the drives, but also the efficiency of the ZFS Adaptive Replacement Cache (ARC) and Level 2 ARC (L2ARC).

To improve the performance for deduplication, the new Fast Dedupe capability was co-developed by TrueNAS and Klara Systems. Internal testing of Fast Dedupe has shown very positive results and confirmed the expected performance. Reads of unique data are largely unimpacted by dedupe, with reads of duplicate data being significantly more likely to be served by the primary ARC. Writes experience a reduction in performance compared to a system without deduplication, approximately 60% slower overall, due to the overhead of hashing and indexing the contents for later comparison and data reduction.

Fast Dedupe performs very well with NVMe drives (which are extremely fast by default) and we will be making this technology available on our F-Series and H-Series NVMe platforms with Fangtooth. With 21 NVMe drives (arranged as 4 x 5wZ1) and fast dedupe, TrueNAS performance was better than a comparable unit with 240 mirrored HDDs.

RAIDZ Expansion has been accelerated

A much-anticipated feature for smaller systems and home users of TrueNAS, RAIDZ expansion allows a small pool (e.g., a single RAIDZ vdev) to be gradually expanded with one drive at a time. Existing data is preserved with its original parity level and rewritten across all drives, while new data is written with the new parity configuration. This simplified administrative process gives smaller TrueNAS systems the flexibility to expand in single drive increments, rather than adding a full vdev of drives. The same expansion feature works regardless of the parity level used – RAIDZ1, Z2, or Z3 – but cannot migrate between protection levels.

The TrueNAS team helped sponsor and complete RAIDZ expansion in OpenZFS.

Many systems have tested this feature with Electric Eel. Because the process of rebalancing requires reflowing the existing data, the expansion often took days on an HDD-based pool. Our engineering team recognized that the reflow algorithms could be improved and have submitted a patch into the final OpenZFS 2.3.0 which typically accelerates this process by 5X, with potential gains up to 10X. TrueNAS Fangtooth will include this feature.

What else is in Fangtooth?

In addition to the major features highlighted above, TrueNAS 25.04 includes much more. At this stage of development, the NVMe Direct IO is not yet validated or activated. In addition, the ability to assign Apps to unique IP addresses or interfaces is in process, but will not be testable until the App catalogs are updated with the Fangtooth BETA release, currently targeted for February 2025.

For more details, see the Release Notes and join the discussion on the TrueNAS Forums, where early testers of the 25.04 pre-release versions are sharing their feedback and tips.

TrueNAS 25.04 “Fangtooth” is planned for formal release in April 2025, and will support upgrades from existing TrueNAS 24.10 installations. Get started today with the free TrueNAS Community Edition, and easily upgrade to Fangtooth upon release.

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