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  1. #1


    Member Since
    Apr 08, 2012
    Posts
    4
    Problems Formatting External hard drive on MBP
    I have a Seagate 1.5 TB external. I can no longer read data from it. I want to erase all data and reformat.

    Conventional Efforts:
    When I plug it in to my MBP (via Firewire 800), it shows up on the desktop as mounted. However, when I try to access the files on it via Finder, Finder crashes (beachball). I open disk utility, and I can see the disk. When I press erase, the dialog is stuck at "Unmounting Disk".

    Why does this happen? What can I do to help debug the problem?

  2. #2

    McBie's Avatar
    Member Since
    Apr 26, 2008
    Location
    Belgium
    Posts
    2,883
    Specs:
    2013 MBA 13" - OS X 10.12.latest
    What happens if you unmount the disk before you go into DiskUtility ?
    Could it be that the disk is being indexed by spotlight ?
    Also, does the disk have another interface to try like USB ?

    Cheers ... McBie
    A computer lets you make more mistakes faster than any invention in human history - with the possible exceptions of handguns and tequila.
    The bitterness of poor quality remains long after the sweetness of low price is forgotten.

  3. #3


    Member Since
    Apr 08, 2012
    Posts
    4
    Quote Originally Posted by McBie View Post
    What happens if you unmount the disk before you go into DiskUtility ?
    Could it be that the disk is being indexed by spotlight ?
    Also, does the disk have another interface to try like USB ?

    Cheers ... McBie
    Attempt in Terminal [Firewire 800]
    Voldemort [~] $ diskutil unmountDisk /dev/disk1
    Unmount of disk1 failed: at least one volume could not be unmounted

    Attempt in Terminal [USB 2.0]

    Voldemort [~] $ diskutil unmountDisk /dev/disk1
    Unmount of all volumes on disk1 was successful

    -- so the unmounting worked here


    Voldemort [~] $ diskutil list /dev/disk1
    /dev/disk1
    #: TYPE NAME SIZE IDENTIFIER
    0: GUID_partition_scheme *1.5 TB disk1
    1: EFI 209.7 MB disk1s1
    2: Apple_HFS THE PIT 1.5 TB disk1s2


    Voldemort [~] $ diskutil eraseDisk HFS %noformat% /dev/disk1
    Started erase on disk1
    Unmounting disk
    Creating partition map
    Error: 22: POSIX reports: Invalid argument

    Voldemort [~] $ diskutil list /dev/disk1
    /dev/disk1
    #: TYPE NAME SIZE IDENTIFIER
    0: *1.5 TB disk1

    -- So the volume information is gone

    Voldemort [~] $ diskutil eraseDisk HFS %noformat% /dev/disk1
    Started erase on disk1
    Unmounting disk
    Creating partition map
    Error: 22: POSIX reports: Invalid argument

    -- but I still can't erase the disk

    EDIT: Even though POSIX gives an error, I then formatted the disk with diskutil, and it seems to be working just fine...

  4. #4

    McBie's Avatar
    Member Since
    Apr 26, 2008
    Location
    Belgium
    Posts
    2,883
    Specs:
    2013 MBA 13" - OS X 10.12.latest
    Sorry mate, but all that technical terminal stuff .... I am afraid you have completely lost me.

    Glad it worked out for you on USB ( if I understand this correctly )

    Cheers ... McBie
    A computer lets you make more mistakes faster than any invention in human history - with the possible exceptions of handguns and tequila.
    The bitterness of poor quality remains long after the sweetness of low price is forgotten.

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