Upgrading FreeNAS from older versions

[tux75at]

Hello,

i have my homeserver allready running for a while, and i think of upgrading. (At the moment i dont know exactly which version, but it might be 8.3 or something, the minidlna was kinda new for FreeNAS)
When i use a second Flash Drive install a new version and configure the most things (i might even try some plugins first, as i need minidlna or similar working).
When the base system is running, is it risky to loose data, when i add my hard disks?
I have two different types of drives, 2x500GB with mirroring and 3x2TB as a 6TB drive, i think ZFS.
Does FreeNAS write anything on the disks when they get added? Can it fail and can i loose data, when i add the disks in the wrong order (Specially the 3x2TB part).

If adding the drives doesnt work, will it work to boot the old system without data loss?

I think only some developer might know the answer, because its mostly about what the system does, when a drive with a working file system is added.

If there is too much risk, i might get some additional drives to make a backup.

 

[Yatti420]

I would just boot up a second USB with latest 9.2.x release and see if it runs.. Then if it goes wrong just go back to your 8.x USB.. http://doc.freenas.org/index.php/Upgrading_FreeNAS

 

[solarisguy]

If you create a ZFS pool using any of the current FreeNAS versions, you would not be able to access it on 9.2.0 and earlier (that is no access to it on anything 8.x).

So it is a one-way street.