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Setting up Hard Drive for two images and choose which one to load on boot up RP3

  • Hi,

    kind of a newbie here

    I was just wondering if the following is possible, ive searched around but struggling with to find an answer

    Currently I can get 1 saved image of retropie to work on my HD by formatting the HD to NTFS writing my image with Win32diskimager, then copying the files Windows sees to an SD card and changing the cmdline.txt so it boots from the HD, then expand the HD filesize via putty to full capacity.

    I have just acquired a 500gb external hard Drive is it possible to split this into two partitions, write 1 image to one partition and another image to another partition, then on boot up choose which image to load?

    As I'm sharing the pi3 with my brother, as the present time we are just swapping SD cards but obviously this way we would both have more capacity and wouldn't need to keep swapping SD cards.

    I've read a little about noobs and berryboot, but not to sure if this helps for my needs

    any help would be appreciated.

    Hope this makes sense


  • Okay so first a BIG disclosure that this is not entirely in my league of expertise, so I may be totally unaware of ways to do this and I hope that if there are simple ways to set this up that other experts chime in with a how to for you.

    That said, of what I do know in theory you would need a boot protocol like in a bios that would recognize multiple images and offer you a selection. That is the part that is way beyond my ken.

    Another idea may be to specify in the cmdline.txt which image to boot to. But then you still need to find a way or do some coding to give you a selection prompt. Again the how to do it is outside my ken

    A different question that prompted me to comment is... "Wouldn't it be easier to get a second pi?" One of the great factors of them is their low cost. If you only have one monitor to share you could set up an HDMI switch to toggle between them. I could see a bar top build with two or three toggle switches off to the side.

    One 2 pole On/On switch for the monitor feed " Pi1 / Pi2 "


    One 2 pole on/off switch for Pi1 power
    One 2 pole on/off switch for Pi2 power


    One Three pole On/Off/On toggle switch to power "Pi1/off/Pi2"

    All other button and joystick connection feed to both Pi's and you decide witch to power up. The three pole toggle would also prevent you running both pis at the same time.

    Do to my skill set I am more of a "fix it with hardware" then "fix it with software" person.

  • Global Moderator

    @shaker777 Booting multiple OS-es on a Raspi can be done via NOOBS - just install 2 versions of Raspbian, one in each partition, then follow the manual installation docs and you can have RetroPie on both.

  • Hi thanks both for the replies,

    So @mitu will give that a bash over the weekend, just curious to know how the pi knows which partition to boot from, take it upon boot up this is where you select your partition and this is a function within noobs

    So once this is set up is it then possible to write your images to each partition of the HD?

    Like I say haven’t read the documentation yet but will give it a go


  • I don't use dual boot, but use OSMC and RetroSMC so that I can use KODI and RetroPie on the same system and also runs solely off the external USB hard drive with the SD card just for booting then control is passed onto the hard drive for much faster speeds and less stress on the SD card as it is now used just for reading . Otherwise I think it would have been dual boot if not for RetroSMC

    In your case, try NOOBS as already suggested or possibly the better option of BerryBoot. This creates a bootloader so you can choose what system to load before the PI even begins to boot up or a default OS to load and also has the option to run the OS off your hard drive with the SD card only used to choose which OS to boot and then pass control onto the OS stored on the hard drive. Plus, quickly reading the guide there is an option to clone your OS so you don't have to do it all again, which I'm assuming means you could set-up a basic RetroPi partition then simply 'clone' that to the 2nd partition and set that up as your brother wants with his RetroPie set up for his use

  • Great, thanks for the help will give it a go, I’ll post back how I’ve got on or if I need some help lol

    Cheers again

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