I want to make my operating system partitions read only, but also to have a separate small partition to occasionally write data. Will the read only OS partitions be safe if the read/write partition gets corrupted from power removal while writing? Or does the entire sd card get corrupted?
If the read only partitions are actually safe in this case, then it should be possible to detect on boot when the read/write partition has become corrupted and reformat it.
edit: This is for a special application where the RPi will never be "shut down" properly, it will just be powered off. I have experience making bootable read-only systems on the RPi and that works great, but I now need a way to keep the system safe from sd corruption while also being able to write a small amount of data sometimes.