If this is the case, the solution would be to simply disable the autoexpansion script at first boot, but I have seen in other posts that might not be as easy as it sounds.I don't kow if you're wrong but last time I tried it (on Buster, I think) the expansion script failed if the root partition was not the last partition on the device. A lot has changed since then though.
To me this has less to do "what is best" and more with "op should be free from constraints doing this".Truth of the matter is that given how the OS is installed onto a Pi's boot media having a third partition doesn't add much if anything.
Because OS installation is by writing a disc image to the drive you still need to backup the data in the third partition first. You then have the extra hoop to jump through of recreating the third partition.
I don't see using rsync from one directory to another as "jumping through hoops". There is no need to mess with partitions at all if "restoring" that way.
Everything in my linux body screams "why is op constrained", linux is about freedom to do whatever I want.A third partition makes sense on platforms with a more traditional installation method but on Pi I find it's better to keep the OS and data on separate physical devices. Much easier to install a major OS update or restore from backup that way.
I totally get that op does not want to use a massive ssd for a root partition, that probably does not need to be much bigger than 10GiB (if running headless, with a desktop, probably a little bigger).
The block in this situation, seems to be the autoexpansion script. If op manages to disable it, it will absolutely work to set everything up before first boot.
Statistics: Posted by bedna — Fri May 10, 2024 8:35 am