iMac late 2015 booting from external SSD. What to do with the internal?

Discussion in 'iMac' started by jck1634, Jul 20, 2019.

  1. jck1634 macrumors regular


    Mar 16, 2009
    Sorry guys I’m sure this has been covered but I don’t seem to have the ability to find any kind of consensus on how to do it. I’ve managed to boot my iMac from an external ssd. The internal HDD is just sitting there not doing anything.

    I was thinking about putting Windows 10 onto it. Boot camp seems to be the way I’d like to go but I can’t seem to find anything consistent by way of instructions for this.

    Any chance anyone has done this and wants to give me a quick step by step guide?
  2. Fishrrman macrumors P6


    Feb 20, 2009
    If you have Windows in mind (I don't do Windows)...

    I suggest you PARTITION the internal drive if you want to do this.

    Use the "first partition" as an ALTERNATE BOOT DRIVE with a copy of the Mac OS on it that is BOOTABLE TO THE FINDER.

    You always ALWAYS ALWAYS want to keep a SECOND COPY of the Mac OS close by that is bootable to the finder.
    What if your external boot drive suddenly won't boot for you?
    (but you know that will NEVER happen, right?)

    Then install Windows onto the SECOND partition.
  3. mikehalloran macrumors 68000

    Oct 14, 2018
    The Sillie Con Valley
    I suggest that's a really, really really bad idea if your data integrity is important to you. Unless running Sierra or older— then it doesn't matter.
  4. faraway52 macrumors newbie


    Mar 3, 2019
    I used the internal HD as a backup of my external SSD system drive. I used CCC to to refresh the backup each Sunday night. It was an easy to have safety net.
  5. Trusteft macrumors 6502a


    Nov 5, 2014
  6. Fishrrman macrumors P6


    Feb 20, 2009
    Yes, Mike.
    Please explain WHY having a second boot volume close by is a disadvantage...?

    I did that for six years with my previous 2012 Mini.
    Kept a copy of the OS (actually a clone of my boot volume) on the slower 1tb internal drive.
    But I booted and RAN IT from an external SSD in a USB3/SATA dock.
    Ran GREAT (I can't overemphasize that).
    In fact, it still boots and runs fine sitting on the other table as my "backup".

    The OP is booting/running from an external SSD (no problems with that).
    But... if the SSD has a problem... he needs a way to get booted and up-and-running in the finder quickly.
    A copy of the OS residing on the internal drive (even if seldom used) will provide that "reserve" for emergencies.
  7. jck1634 thread starter macrumors regular


    Mar 16, 2009
    Thanks for all the advice. I unplugged the ssd and partitioned the internal hard drive in half and so now it has MacOS and windows 10. It’s nice to know I’ve got that safety net still in case something happens to macOS on my ssd. Now the only problem I seem to have is trying to get windows to recognise my Magic Trackpad 2 as a trackpad and not a mouse. Tap to click, double tap to right click, none of these are working. I was expecting an Apple software update window to pop up and install the drivers but nothing like that’s happened. Any suggestions?

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6 July 20, 2019