You only need N(2) if you're updating by downloading and switching to an entire second rootfs image. If your OS takes up 500MB and you update a single 5MB compo

You only need N(2) if you're updating by downloading and switching to an entire second rootfs image. If your OS takes up 500MB and you update a single 5MB component, then you only need 505MB, and that only until the update completes and the old version is dropped and you return to 500MB.