I installed High Sierra..boot drive disappeared..help..

Discussion in 'macOS High Sierra (10.13)' started by Krackle, Apr 11, 2018.

  1. Krackle macrumors newbie

    May 1, 2015
    Hi Folks...

    I installed High Sierra..Then, later.. rebooted my Computer from my old Mavericks boot disk..

    Poof....can't see my new High Sierra drive..(which was an update straight from Mavericks..was told, by several folks, it would be ok to make that jump..Everything worked fine when i was booted in the fresh install...

    It shows up as "Disk Os2" in Disc utility but it's greyed out..can't do anything with it..

    The machine is currently booted in Mavericks

    I'd like to get this disc "Disk Os2.. up and running..realized there is a tiny bit of data that i need that wasn't backed up..not crucial..but causing me to jump through a bunch of hoops..


    (after reading a bit I'm finding that there quite a few instances of discs going away after High Sierra installs)
  2. treekram macrumors 68000

    Nov 9, 2015
    Honolulu HI
    If your High Sierra disk is in APFS format (the default when installing High Sierra on a SSD), then a Mavericks-booted system won't recognize it. Unless you had a problem with the High Sierra disk, it's still there. Are you no longer going to use High Sierra? Do you need to use both High Sierra and Mavericks on the same computer?
  3. DeltaMac macrumors G3


    Jul 30, 2003
    If you have upgraded to High Sierra, then you would need to boot to the Recovery system to see the drive in Disk Utility. It is not accessible from Mavericks - the system won't recognize an APFS format SSD.
    (actually, you can view the APFS drive from a Sierra system, too, but def not from Mavericks)
    If you need to find out how to boot from either system, you can choose either system from the Option-boot screen.
  4. Krackle thread starter macrumors newbie

    May 1, 2015
    I can't seem to boot into that Option -boot screen,...i've tried all combo of pressing the option button and I get a light great screen and nothing..

    odd thing is..I went to reset my PRAM...all went well..and then the machine booted into High Sierra..and Mavericks, for sure , was the selected boot disc..

    I can repeat this action over and over..when i rest PRAM..this machine boots to High Sierra every time..

    Yesterday I downloaded and installed Regular Sierra and the advice of a friend..had similar issues with that...Mavericks not seeing the Reg Sierra disc when I booted back into Mavericks..
  5. DeltaMac macrumors G3


    Jul 30, 2003
    That's your Mac Pro, correct?
    Do you have a non-Apple graphics card installed that does not show boot screens?

    What format is the Sierra system drive? Latest version of Sierra supports APFS format, but Mavericks won't see that drive. It's the same situation that you had already with High Sierra.
  6. Krackle thread starter macrumors newbie

    May 1, 2015
    Hi Delta,

    Yes Mac Pro..

    From get info screen on the Sierra Disk: Mac OS Extended (Journaled)

    (The High Sierra Disk is APFS in info)

    Graphics info:

    NVIDIA GeForce GT 120

  7. DeltaMac macrumors G3


    Jul 30, 2003
    Are the High Sierra and Sierra systems on different drives (different slots on your MacPro), or on different volumes on the same drive?

    There really are not "combos" for choosing Option, unless you don't have a Mac keyboard (and you have Windows keyboard - with a Windows key.)
    Not all third-party keyboards will work for the Option boot screen.
    You would press the Alt key on a Windows keyboard (not the Windows key) on during boot, to get the Option boot screen.
    If you ONLY get a grey screen, be sure to wait for the drives to appear. Should come up within a few seconds, but, just in case there is a mounting issue, give it a couple minutes.
    When I have boot issues, I do a PRAM/NVRAM reset at first boot:
    Press and release the power button, then hold Option-Command-p-r.
    You should hear a boot chime sound. Keep holding the same 4 keys until you hear the boot chime two more times.
    Then, while the chime is still playing, release all keys except continue to hold Option (Alt). That might get the system to show the boot volumes on that boot-picker screen. Again, give it some time.
    note: the NVRAM reset WILL unset whatever boot drive is selected in the Startup Disk pane, so you would need to set that again, when you have booted to your system.
    I think that the hardware will try the lowest slot with a bootable system first. So if your High Sierra is in slot #1, the reset may default to that slot if you can't see ANY boot volumes on the boot picker screen.

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