Hello
This is my first post ever here and I had hard time to find where to post this, so hopefully its the right categori. If not, just point me and I will post it in the right place and if possible remove this post.
Now to the post:
I started using FreeNAS many years ago for the datahealing abilities. All my data is on the server while I access it using SAMBA from my Windowsystem.
Due to different reasons (no backups …) I have not been jumping into every upgrade but rather waiting with upgrading. I did a few upgrades but then stayed on FreeNAS-11.0-U4 (54848d13b). I stayed so long on that version and now there is no more FreeNAS but TrueNAS. The plan is not to stay on FreeNAS forever but upgrade to TrueNAS in the easiest safest way.
Let me add that I use my FreeNAS only as a storageserver and my pools are NOT encrypted. I have no jails or anything aditional configured. I do regulary scrubs and SMART test, the core stuff.
Upgradring to a new FreeNAS version using the GUI and downloading new FreeNAS versions is not possible anymore. I am not sure at all how to best go on downloading newer images on my windowsmachine and somehow transfer it so that FreeNAS can use it to upgrade, after all its serveral versions.
What I wonder is if it is possible to just download latest TrueNAS, install it on another USB stick, remove the current sticks with FreeNAS and plug in new one with TrueNAS and finally just import my 2 pools.
For me this seems to be the easiest way, but not sure if something can go wrong here for some reason when am so many versions after ?
My server has 2 pools raidz3 and I dont have any external backups of all my data. That would require another server as I do have a lot of data.
You will find all the early Freenas Manual Update files here :
https://download-core.sys.truenas.net/
I seem to recall that the recommended stages were to got to the latest 11.X then to the latest 12.X then finish at the last Core 13.0-U6.2. Don’t go to 13.3.
Make sure you have enough space in the Boot-pool so you can revert if needs be. DO NOT upgrade the ZFS Features so you can revert.
Oh, are your pools encrytped ?
Hey @arameen
We don’t recommend USB sticks any longer for endurance/durability reasons. Is there an available SATA port or M.2 slot for an NVMe boot device?
But aside from that, yes, you can import your two pools to a new installation. Depending on the complexity of your setup, you may want to back up your configuration and attempt to import it on the your new TrueNAS install.
There’s some caveats - encryption is one. If you’re using it, you’ll need to back up your keys (I’d suggest multiple copies) and use them to import/restore. Legacy encryption will also prevent you from choosing SCALE.
The second would be things like having shared your root dataset (eg: /mnt/poolname instead of /mnt/poolname/sharedfiles) which is discouraged now and will probably, at the least, pop up a warning dialog.
And if you’re connecting to your shares with the username root you can expect that to not work either, for security/compatibility reasons.
Things have changed since FreeNAS, the USB stick skip is a suprise I was not prepared for as I had lots of extra USB sticks for the OS. It worked fine saving ports on the motherboard. Are USB sticks a completly No No ?
I udnerstand I should do some reading on recommendations for new installs and hardware. If you have links I appreciate if you post them to me. Still very new here 
I did a fast check and luckily I have one SATA port not occupied, all are taken due to man disks in my chassi.
However not sure about the NVME, what it even means 
Did not find anything about NVME in the manual of my motherboard, SuperMicro X10SL7-F
The pools are not encrypted, update the post about it. Did have encryption with FreeNAS many years ago but skipped it after some issues and reading to many posts about potential risks.
Installing TrueNAS and just importing the pools would be great if it works, I just don’t wanna try it unless there is on risk with it why am asking about it first. And if importing the settings do not work, am totally fine with that. I can add scrubs, SMART tests and share over SAMBA again. Its not a big thing compared to upgrading lots of FreeNAS versions to come to TrueNAS.
I am not connecting to shares with root.
Not sure about the shared rood dataset. I do see the system dataset pool residing on one of my 2 pools when I look in the GUI.
Back to the importing, are there any risk with tryign to import the pools to a new installation of TrueNAS when just removing the sticks with FreNAS ?
Running zpool get versions on both pools gives me "Value - " and what I found about it is that the pools are using feature flags (pool version “5000”). Whatever that would mean for just connecting those to clean new TrueNAS installations 
Thanks, I did find all that before.
I just wanna skip some steps, upgrading so many versions while it could working with a new installation. Also not sure I can manage the upgrading that way as I somehow need to get the upgrade files into the system, Am not good at FreeBSD at all.
Updated the post, no encryption
USB sticks are generally of lower endurance than a comparable SSD - they don’t tend to have the same quality control on the NAND, or features like wear-leveling and TRIM. A USB device attached via a USB-to-SATA convertor can be a viable option here if you don’t want to dedicate a SATA port to it.
Nope, that would be the best approach. You could set up a new installation, and import your pool into TrueNAS (SCALE or CORE) - from there, the crucial piece is to not upgrade the pool itself until you’re sure you’re ready to stay. ZFS is backwards compatible, in that you’ll be able to import the older version just fine - but if you upgrade and enable a feature that isn’t in your previous FreeNAS install, it won’t be able to import the pool there.
the good thing with having usb sticks with FreeNAS was that it was very cheap with dualboot. Sooner or later the SATA drive running TrueNAS will die, and with one only it will cause problems
What kind of futures in the pool are we talking about? I dont recall having a seperated poolugprades with FreeNAS. So not sure what to expect with TrueNAS, why I would like to upgrade the pool and how long to wait with that