Unless there's another volume that isn't visible from your screenshot, that other volume is probably your Time Machine volume. Is Time Machine on an external volume that's connected to your computer? If so, that System Reserved volume is on your Time Machine drive. Ejecting both would mean you wouldn't be able to backup to Time Machine, but remounting the Time Machine volume is easy.Can I eject all on the desktop? I saw my external hd. Is it different than the aother system reservted?