Possible to attach existing ZFS Pools from a TrueNAS Core to a clean install of TrueNas SCALE

I am clueless. I have googled and not found more than migration instructions. The thing is that I don’t want to migrate my config, I just want to do a clean install and attach my existing disks.

I run an old TrueNAS 12.0-U3 at home (personal use) today and would like to go TrueNAS SCALE.
I do not care about my setup but I do care about my data.
It’s two mirrored SATA WDC WD120EDAZ-11F3RA0 with 3 Pools where 1 is encrypted.
All are lz4 compressed and no dedup.

Is it possible for me to install a clean TrueNAS SCALE to the SSDs (where the existing TrueNAS is installed) and then attach the ZFS Pools that I am currently running without data loss (on the SATA disks of course)?
Anyone done it? Anything I should be aware of? Anything I should look out for?
(Yes, will make backups of the files I can’t live without but I’d prefer not having to restore)

zfs can be imported on a new system. ACL attached to fs will be preserved as long as you have same user group names.
But share information and configuration will not go with ZFS. For example, smb ACL might require revisited.
If you have any jails on it. You are likely to rebuild these.

Thanks for the ultra fast reply.

My worries are about the compatibility of partitioning and ZFS versions between TrueNAS 12.0-U3 and TrueNAS SCALE.

I want to start the setup of my NAS from scratch (because of old legacy stuff built on mistakes that was built on mistakes) and the ACLs will be cleaned out as soon as I am sure all data is intact. No jails, no nothing should be moved over to the new setup.

You should be able to export and import no problem. ZFS is ZFS AFAIK.

So l I need to export ZFS first in the old setup, install new TrueNAS SCALE and then import ZFS?

No need to worry about ZFS versions. New version will import old version and will offer to upgrade. You can choose to upgrade to new ZFS if you want. If the old version works fine, I do not suggest an upgrade without full backup.

It seems you are using GELI encrypted pool. I don’t know if SCALE support importing GELI encrypted pools as ZFS has moved to the newer Native encryption scheme.
TrueNAS CORE will allow you to import GELI encrypted pool as Legacy, but you really need to migrate your data to a pool that is created with the newer ZFS version.
At least, make sure you have your GELI keys saved and accessible some other places.

Not if you are using GELI encrypted pools.


God no! I left GELI. This is a ZFS encrypted pool. Only one out of three is encrypted.

Hundred years ago I added a disk and all went well… Until I rebooted and I lost everything because adding a new disk changed the encryption key.
After that I always made sure to have exported key on USB memorystick hidden in another place.

It’s that trauma that is making me nervous about my little migration adventure here.

I only migrated from GELI to the new Native encryption a few month ago.
So you are using the Native encryption then?
In that case, according to iXsystems (need to be double checked, though), TrueNAS SCALE can access CORE pool and vice versa, at least from the point of view of the latest CORE 13.1.
I think there is a path for upgrading from TrueNAS but you need to be update to TrueNAS 13.1-U6 and then change the release to SCALE. This process should let you keep the existing snapshots of the boot environment and you can then go back to CORE if this doesn’t work for you.
At least, this is the theory. I personnaly have no experience with the upgrade path.


The boot disk upgrade is one way. The boot loader gets replaced.

BUT if you mirror the boot disk first, then remove one of the members (as in physically) then you could switch to that physical boot disk to go back.

FWIW, I found the upgrade in place worked well.