Total Truenas Newb here. I recently upgraded my setup to Fangtooth 25.04. I notice I am getting this notification since upgrading:
New ZFS version or feature flags are available for pool ‘data’. 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.
My question would be how risky is this? I don’t have any immediate plans to ever downgrade, and I am not running VMs on this setup, just a bunch of containers. Does this ZFS upgrade require any downtime to do?
No, it’s nearly instantaneous and done while the system and pool are online.
Upgrading the pool isn’t in itself risky; it just enables additional features that you may or may not use. The biggest concern is noted in that message, and that’s that it can prevent a downgrade. If you’re certain you aren’t going to downgrade, there really isn’t any reason not to.
I second Dan here. Been through a lot of updates over the years. Zfs gets improved and your system can use those improvements as long as the flags are set on the pool. You can literally go to your storage where your pools are listed and click upgrade on each pool, takes about two seconds each.
Only reason you wouldn’t is if you planned to roll back. Zfs wouldn’t know what to do with the new flags on an older version.
