I run my TrueNAS Core OS from a USB stick, a SanDisk Extreme USB 3.0 32GB stick plugged into a USB 2.0 socket, inside the box and on the motherboard.
The machine is an HP N54L with 16GB RAM and running a RAIDZ2 with 5*4TB spinning disks.
This actually WORKS, I think only because the OS actually runs from RAM (or does it??? I’m no longer sure…).
If this works satisfactorily for Core 13.3 could it be made to work to roughly the same perf level for SCALE 24 and later???
IMHO better replace the USB stick (don’t know if Is a SSD one) with at least a genuine SSD SATA+ USB adapter… Or better a cheap NVME + PCI-ex adapter (if a slot Is available, and the mainboard Is not too old to boot from NVME)
As already pointed, yes, in this case NVME way Is not viable (didn’t check you Hw honestly before).
Scale write a lot more on the boot pool than Core, so have a genuine SSD should provide better reliability… But considering that you have already one, if you want to try It anyway just be sure to have your config backup updated… In case the stick die Is just a fresh install + config upload to come back online (and if a spare Is available in the house, downtime will be trascurabile).
Having an internal USB port Is a good thing, avoiding accidentally “phisical collision”.
Also IMHO don’t buy this sticks anymore in future, in case you need to replace this one, most because of that and but also because those are more expensive than a genuine small SSD, Is not convenient at all.
I have run Scale with USB>SSD for some months without issue, i switched to NVME because my SSD die and grabbing small Optane was ridicously cheap (3-4€ each), instead the price of small SSD was bit higher due the fact actually Is hard to find something below the 256gb.