Great tool. Definitely it gives quite some level of confidence.
Just be ready, it might take quite some time before it is completed.
Just as a reference: 10x12TB set of disks on Xeon system was up and running for ~7 days before was completed.
But then there is a good understanding about the setup.
Wanted to say thanks for this, very useful advice for a super niche case most people probably won't (and shouldn't) really need!
In my own use-case I had an awkward juggling match to deal with; when I got my four bay box, in an ideal world I would have got four disks and just setup a RAIDz2 on day one (for half capacity with two disk redundancy and maximum read performance not a concern) but because of the disk prices at the time it wasn't within my budget to get four smaller drives, biggers ones were better value but I could only get two so had to go for a basic mirrored pair.
Fast forward to when I can afford another two and my choice was either add another mirrored pair and just accept single disk (guaranteed) redundancy, or use what your guide showed. In my case I created a RAIDz2 with two disks and two sparse files, offlined both files, copied my data into the degraded pool, then replaced the sparse files with the disks from the original mirror one at a time.
While doing it this way meant there were technically always two full copies it was still pretty hair-raising, but my offsite backup doesn't keep as many historic snapshots so I really wanted to preserve them if I could.
Top notch! One thing I ran into on my system, 2 Truenas-12.0-U1 servers in master/slave, is that I needed to ensure the "Power Off UPS" setting was not turned on for my config. Otherwise part way through the boot process after the shutdown it would kill the UPS power and the kill the power to my Server mid boot.
Great easy guide .. I just skipped the media folders part and used the mount points via the web gui. I was using the plex plugin for a long time and my OCD got the better part of me when I couldn't update the jail to 12.2 and was stuck on 12.1.
I had one little issue where plex wouldn't start after adding mount points, but running:
iocage exec 3DPlexPass service plexmediaserver_plexpass start
again seem to correct the issue and plex starts on it's own again after stopping the jail.
The only thing missing is a consideration of CMR drives vs SMR in the NAS drives section. This may have been done to avoid controversy / drama in the comments section, but it's an important consideration, regardless.
This was the single best guide for setting up my two Truenas 12.0 U1.1 servers on a single UPS. Thank You !!! Minor detail: the UPS name set on the slave system needs to be the UPS name on the master system.