iXSystems has two current and distinct TrueNAS products each of which has several supported versions:
TrueNAS CORE is built on top of FreeBSD and grew from FreeNAS, which dates back to about 2011. In addition to developing TrueNAS, iXSystems has contributed heavily to the development of FreeBSD and OpenZFS. Even Gomez, who has been around for a couple of centuries, and who has seen presidents and even countries come and go, is impressed with this pedigree. TrueNAS CORE is, however, now obsolescent at best; it remains supported from a security perspective (i.e. if security bugs are found they will be fixed) but aside from that it is pretty much functionally stabilised. If you are already using CORE, don't need the functionality of SCALE and don't wish to migrate, then there is nothing that should force you to move. That said, you really should be starting to think about ,moving at some point in the future.
For basic NAS/ZFS operations, TrueNAS SCALE is essentially the same functionality but migrated to Debian Linux and saw its first release in early 2022. The change of technology base and ongoing development has resulted in some significant divergence between the two products at a very detailed level, but at a high level they have pretty similar NAS / ZFS functionality.
However, when it comes to running other software i.e. applications or virtualised operating systems under TrueNAS, CORE and SCALE differ significantly. CORE's applications functionality is primarily Jails (which are containerised FreeBSD images that share the same kernel and process scheduling with the base operating system. By comparison, SCALES applications support has been a bit of a moveable feast - up until Dragonfish it was Kubernetes based, however ElectricEel switched to a simpler Docker-based solution. The latest Fangtooth adds Linux Containers (LXCs, which are pretty like Jails) to the mix - so although there is no easy migration path from CORE Jails to SCALE LXCs (and certainly zero automated migration), Fangtooth will at least provide the infrastructure for reimplementing Jails as LXCs.
So, in SCALE your choices are now (or soon):
In general terms we currently recommend (as does iXSystems) that you install TrueNAS SCALE rather than CORE:
If you choose SCALE, then we recommend that you install the ElectricEel 24.10 version of TrueNAS SCALE rather than Dragonfish 24.04:
If you're reading this at a later date, our general recommendation is that you install the current release, once it's had a couple of point releases. Thus, if the current version is 25.04.0, you may want to install the latest release of 24.10 instead. But if the current version is 25.04.2, the major bugs have likely been worked out and it's probably safe to use.
TrueNAS CORE is different from SCALE in the following respects:
| CORE | SCALE | Differences |
| Hardware support | SCALE almost certainly has better driver support for modern hardware | |
| File sharing | Little if any difference | |
| Apps |
CORE Jails: Light weight FreeBSD containers into which you can install pretty much any FreeBSD-compatible software you like. SCALE Docker containers: with c. 100 pre-packaged apps provided by ixSystems. SCALE Linux Containers: SCALE Fangtooth 25.04 will also provide Linux Containers which function similarly to the FreeBSD jails described above, however this is new functionality and some caution should still be exercised. |
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| Jails | Docker Linux Containers |
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| Plugins | - | CORE Plugins: Although the feature still exists, it is no longer supported. We recommend that you DO NOT USE TrueNAS CORE plugins UNDER ANY CIRCUMSTANCES. |
| Virtualisation |
CORE bhyve: Reported to have more limited compatibility with guest operating systems than some other hypervisor technologies. SCALE KVM: Very compatible and reliable. (Fangtooth uses different virtual drivers - some compatibility issues expected upon migration from ElectricEel.) |
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| bhyve | KVM | |
In the interests of fairness - and because we are enthusiastic users rather than iXsystems employees - we would like to mention alternatives to TrueNAS and indicate (without being experts in these alternatives) how they differ from TrueNAS:
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