This is close to correct. the cat /proc/mtd has different output layouts between the 2 different version, mostly due to the busybox/debian difference of OS. So, thats more of a proof of concept as well. The takeaway from the whole thing, and the main thing to be done, is to remove the OS from the internal flash, while leaving the “boot” and “recovery” alone. this is why we would issue the nandwrite to the mtd3. This is where the OS is installed and functions from, at least on the EX2 Ultra/Gen 2 devices. The rootfs image that was written, was simply a file (could be any number of files) that will write to the nand, which is basically doing a mass delete ( rm -rfv / ) of the root partition while leaving the boot files.
Does this destroy the files installed on the Flash Ram? Yes
Does this make it boot into safe mode on reboot? Yes
Does it allow the old firmware to be reinstalled? Yes
Does it allow you to make it back to OS 3? Yes
Does everything function and work as it previously did, before upgrading to OS 5? Yes
Challenge Completed in my book…
as @NAS_user stated, it can be done without drives, it can be done with dummy drives, and when you run thru the initial setup again on OS 3 from OS 5, it will tell you there is a “roaming” volume and import it into the NAS.
