formatting "Couldn’t Unmount Disk" - error

Discussion in 'MacBook Pro' started by Calby, Feb 4, 2017.

  1. Calby macrumors 6502

    Calby

    Joined:
    Dec 30, 2015
    Location:
    Sweden, Gävle
    #1
    Hi,

    I don't think this is a issue but I just want to ask if this is a expected behaviour.

    When I start the computer in recovery mode (cmd+r) and I'm trying to format the drive I'm getting a error after a little time "Couldn't unmount disk" but if I'm trying to format the Macintosh HD partion it do work without any error.

    If I boot up trough a USB drive (alt(option)) I can format the "main" drive without any issues, I can also format it if I'm booting up from internet recovery (cmd+alt(option)+r)

    Is this issue because when I'm starting in recovery mode it starts up from the recovery partion and because of that I can't format the "main" disk but only the "Macintosh HD" partion.

    But when I'm booting from USB drive and internet recovery I can format the "main" disk because then the disk are not busy because of the Recovery partion.

    Is this correct?
     
  2. Weaselboy Moderator

    Weaselboy

    Staff Member

    Joined:
    Jan 23, 2005
    Location:
    California
    #2
    Yep... spot on. What you have described is exactly how it works. :)
     
  3. Calby thread starter macrumors 6502

    Calby

    Joined:
    Dec 30, 2015
    Location:
    Sweden, Gävle
    #3
    Thanks Good to know!
     

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