FreeNAS recently released a major update. Since I am only using mine for backups, I had no fear in just blindly going for it! First step was to download the UPGRADE file from Freenas.org, then go into my FreeNAS and choose "update firmware." I choose to download a backup configuration file before hand. The upgrade files are stored on the FreeNAS unit, as I boot off of an 8gb USB thumb drive, I choose to store the files on the only data store. Several reboots and roughly 10 minutes later, the system was back up.
One item of note, is that v9.3 does NOT support UFS! My first build I ran UFS as I am using a lowly Celeron CPU and I originally started out with only 4gb of ram. After the upgrade, I had no storage! What made it interesting is that I could just reformat the 2nd hard drive and create a new volume set. I could not with the 1st hard drive; it gave errors about permissions of the GPT. What I did to remedy it was to low-leveling the 1st disk using a 3rd party application.
Now I had to re-setup my CIFS share and iSCSI targets, no big deal, but annoying. The iSCSI settings where there, I just had to repoint the extent to its new location.