Well, that appears to have gone remarkably well :)
After remembering how to access the BIOS through IPMI to change my boot device, everything ran through almost as expected. The config didn't pull through, but after uploading everything appears to have restarted as before (jails for ownCloud, Plex, OpenVPN and my CentOS VM in vbox which I run CrashPlan has also started back up)
I do have a problem with replication, which is giving me lots of red warnings:
Code:
May 19, 2017, 11:48 p.m. - Replication APEpool1/backup -> 192.168.n.x: APEpool2 failed: Failed: Permission denied (publickey,password).
I have several replication tasks setup which copy data from one FreeNAS box to another overnight. I've edited one of the tasks and rescanned the SSH key, but still the same error. I'm wondering if this is a problem as the backup FreeNAS box is still running 9.3.1, but worst case I have to recreate the replication tasks after updating the other box. I think that's probably a job for tomorrow, as I'll need to find a keyboard and monitor to do that one. You can only have so much to worry about in one day!
Update - figured out the replication issue too! Just needed to copy the public key from the PUSH system into the root user on PULL. A good nights work if I do say so myself :D