theunk7:
From experience, I can confirm that there’s only one OS image on built in FOB (on older systems it’s smaller than 4GB). When starting ‘initialize NAS’ the first screen will have either QTS or QTShero at the top and screen (reflecting current fob contents) gives you the option to switch OS’s. If you DON’T switch os’s you get three choices current image fw vs.download latest vs. fw image you provide (which will be rejected if OS doesn’t match current os shown at top of that screen). If you ask to switch os’s, you only get latter TWO choices because current image is for the os your looking to change from.
If qnap didn’t have the wonderful option of migrating to different physical device and even entirely different model’s I suspect it would just come up with whatever current FOB os image is there without bothering to look at contents of disks at all, but it DOES LOOK at disk partitions and will look to migrate if those differ from fob image. But with DIFFERENT OS configurations on different disks (not normally possible without your choice of when you re-inserted old hero disks while powered down), the choice stretching beyond FOB image vs. DISKS image which it can handle, but by making that choice FOB image vs. NVMes image vs SSDs/HDDs image there is an issue. The modification to your procedure I have suggested or the full wipe of all disks before re-use in nas suggested by Dolbyman will prevent this quandry creating ‘unexpected behavior’.
My two latest models no longer offer ‘secure erase’ option in Storage/Snap->Disks so when I look to follow Dolbyman’s advice to wipe disks, I use a different QNAP that still has that option. If I take it to a windows pc to format, you have to manually remove those hidden partitions (q ‘secure erase’ handles that). But new or ‘wiped of all previous qnap use’ SSDs and HDDs would have bypassed issues you encountered
So, if my system doesn’t have the ‘secure erase’ option and I want to fully reset both the NAS and the disks to factory settings, the only solution is to run SSH commands or connect the disks directly to a PC to manually remove the partitions and completely wipe everything? I can’t believe it!