Can you run Mohave only from a USB drive?

Discussion in 'macOS Mojave (10.14)' started by ToddJ, Jun 29, 2018.

  1. ToddJ macrumors 6502

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    May 23, 2008
    #1
    This might be a dumb question...can i run the public beta of Mohave from a USB thumbdrive only (and not install it on my computer at all?) Yes, I checked my friend Google, but couldn't find a definitive answer...
     
  2. DeltaMac macrumors G3

    DeltaMac

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    #2
    Yes, you can install Mojave on a USB thumb drive, and boot to that installed system on any supported Mac.
    You would want to have at least a 32GB flash drive.
    Good for testing, if system performance is not an issue for you. Thumb drives are OK for booting when installing a system, but not really for general system use. It's just not a good use for USB flash. SSD would be a much better experience.
     
  3. BookEmDanno macrumors 6502

    BookEmDanno

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    #3
    Yes you can and boot Mojave from there. BUT (and it's a big one), performance is awfully slow. I also tried an external SSD drive. It's faster but not by much. My option right now is I am running from 2 separate partitions on my internal hard disk (in this case SSD) ~ 1st on High Sierra, and 2nd Mojave.

    Regards.
     
  4. Fishrrman macrumors P6

    Fishrrman

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    Feb 20, 2009
    #4
    Question:
    "Can you run Mohave only from a USB drive?"

    Yes.
    You can run it from a firewire drive, too.
    You can run it from a platter-based external hard drive, or an SSD.
    You can even run it in HFS+ if you want (I put up a thread on that in this forum).
     
  5. netdudeuk, Jul 1, 2018
    Last edited: Jul 1, 2018

    netdudeuk macrumors 6502

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    #5

    I came here to ask a similar question. I have a new external platter-based hard drive.

    A few questions …

    I'm guessing that you get asked which drive you want to install Mojave onto …
    Does the Mac ask on start up which OS to boot ?
    What happens if you want to boot the Mac without the hard drive attached ?
    If you don't want to keep Mojave, can you get the Mac to basically forget about Mohave and always boot from the internal SSD ?
     
  6. redheeler macrumors 604

    redheeler

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    #6
    The Mac will boot by default to whichever OS is selected in System Preferences > Startup Disk. So go there and make sure the internal drive is selected following the Mojave install.

    To boot from Mojave without setting it as the default, start your Mac and hold down Option until the boot menu appears.
     
  7. DeltaMac macrumors G3

    DeltaMac

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    #7
     
  8. netdudeuk, Jul 1, 2018
    Last edited: Jul 1, 2018

    netdudeuk macrumors 6502

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    #8
    Thanks both for the comprehensive replies.

    Can you remove boot options from the Startup Disk menu in order to leave the Mac like it had never seen Mojave ?

    Thanks
     
  9. DeltaMac macrumors G3

    DeltaMac

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    #9
    Yes, of course. If Mojave is installed on an external drive, eject/disconnect that drive. That choice to boot from Mojave will immediately disappear (right in front of your eyes!)
    Or, if you need to leave that drive connected, maybe because of another partition that you use, then simply erase that Mojave partition. You can't have a boot choice that doesn't exist (or your system can't see because it's not connected to your system.)
     
  10. ToddJ thread starter macrumors 6502

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    May 23, 2008
    #10
    For some reason it won't let me install Mohave onto my USB drive......not sure what I am doing wrong....
     
  11. DeltaMac macrumors G3

    DeltaMac

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    #11
    I just reinstalled Mojave on an external USB SSD, which is number 3 or 4 of external USBs that I have installed Mojave.
    In fact, it modifies that partition to APFS, even though the device is formatted as Mac OS Extended, and the nine other partitions on the same device remain as Mac OS Extended.

    When you try to choose that USB as a destination, what kind of message to you see? Not enough space? or just a generic "Cannot install on this drive"? Be sure to check the format of that drive. You can see that in a Get Info window for the drive. Should say Mac OS Extended (Journaled), or APFS. If it says anything else, like Fat32, or even NTFS, then that's the problem. The external will need to be formatted again, using your Disk Utility. Choose the drive, click the Erase tab, and make sure that Mac OS Extended (Journaled) is what you use. You COULD format it as APFS, but the Mojave installer will do that for you. Make sure that the Scheme selected is GUID (and NOT Apple Partition Map, and not Master Boot Record). When the settings are correct, erase the drive. Might be a good idea to erase, even if the settings APPEAR to be OK. It only takes a few seconds to do that.
     
  12. ivnj macrumors 65816

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    Dec 8, 2006
    #12
    No not usb only? I partitioned my internal into 2 and have high sierra on half and mojave on the other half.
     
  13. ToddJ thread starter macrumors 6502

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    #13
     
  14. DeltaMac macrumors G3

    DeltaMac

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    #14
    3 steps:
    Step #1: Reboot to your installer. Erase the external again (make sure that the format is all correct, from my post #11
    Step #2: Shut down, so your Mac is Off.
    Step #3: Restart to your installer, with your external USB still attached.
    And, try the macOS install.
     
  15. ToddJ thread starter macrumors 6502

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    May 23, 2008
    #15
    When you say ‘Reboot to your installer’ you mean the USB drive right?
     
  16. DeltaMac macrumors G3

    DeltaMac

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    #16
    Yes, the USB storage device/flash drive -- whatever you have for a bootable installer.
     
  17. Cattus Thraex macrumors newbie

    Cattus Thraex

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    May 30, 2018
    #17
    You can, of course.... there seems to be an issue, though. Current version of Mojave cannot check the SMART status of an external drive, so after installation any reboot is very slov, you have to wait some 2 min. until you see the Apple on the screen. After that moment, all is OK, and the speed quite good. I installed H.S. on an external SSD, and was OK, it turned worse after upgrading to Mojave. This seems a bug to me, to be hopefully solved after the first update.
     

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16 June 29, 2018