Upgrade zpool recommended?


I am happily running truenas on a small home server and I just upgraded from CORE to SCALE, so far so good. I am getting the notification again that a “New ZFS version or feature flags are available for pool ‘pool0’. Upgrading pools is a one-time process that can prevent rolling the system back to an earlier TrueNAS version. It is recommended to read the TrueNAS release notes and confirm you need the new ZFS feature flags before upgrading a pool.

Do you recommend upgrading the pool? Can this be done online? Is this done by zpool upgrade -a?

zpool status -v shows
  pool: pool0
 state: ONLINE
status: Some supported and requested features are not enabled on the pool.
        The pool can still be used, but some features are unavailable.
action: Enable all features using 'zpool upgrade'. Once this is done,
        the pool may no longer be accessible by software that does not support
        the features. See zpool-features(7) for details.

Check the documentation for what the new feature do. If you do not need them now I see no reason in upgrading. I haven’t upgraded my existing pools since the new flags were an option. Imo it’s safe to ignore.
But you should be able to upgrade from the GUI iirc.


DO NOT RUSH. If you don’t know what new features are brought in, you probably don’t need these. Upgrading prevents rolling back to a previous version of TrueNAS. Not upgrading never puts data at risk.

If you do eventually upgrade, do it from the GUI and only upgrade data pools, not the boot pool (this can break the bootloader, especially on SCALE). One never ever needs new feature flags on a boot pool.


Thanks for your quick replies… I am not missing any feature, so I’ll wait.

How would I even find out which ZFS features are involved here?

Only once you’re sure you won’t want/need to go back to CORE.

If by “online” you mean “through the web GUI,” then yes, and that’s the best way to do it. If you mean “with the pool online,” the answer is also yes.


The problem with that command is that it upgrades all your pools, including your boot pool. And since Grub is dumb, that will cause your system to fail to boot.

Thankfully, doing it from the GUI will mean you won’t be upgrading the boot pool, since the GUI doesn’t present that as an option.


One note, you can upgrade / enable a specific feature if desired. I don’t remember if the GUI allows this, but you can do so from the command line.

For example, if you want to try, (or need to try), newer compression algorithms, you can enable just that specific feature.

In general, you want to make sure your prior boot environments also support new features. If not and you upgrade a data pool’s feature(s) to something not supported by an older boot environment, you might as well remove that old boot environment.

Does it honor compatibility lists? I think it does, but haven’t checked.

I don’t think compatibility lists have been used in the past, though I recall some discussion on the old board of adding them, perhaps with 24.04?