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  1. #1


    Member Since
    May 03, 2011
    Posts
    3
    iMac unmounts external drives
    I have a long-standing problem with my 24" iMac. When running Time Machine backups, the backup would proceed normally until a notice appeared that the backup disk had been ejected improperly last time. At that point, the backup would stop. The drive was definitely not ejected improperly. I erased and reformatted the drive several times, with no results. I have restarted the iMac and tried everything I can think of. At first, I thought this was a TM problem, and then a problem with the external hard drive. However, this behavior now occurs when I use a USB reader to download Canon photos to the internal drive. (The same USB reader works fine on my MacBook Pro.) The problem seems somewhat random; it appears that there is a triggering event by the system, but I can't figure out what it is. I'm running 10.6.7. I spent a huge amount of time on this with Apple while I still had AppleCare, to no avail. Can anyone help?

    Apologies if there is a thread for this and the problem has been solved. This is my first post, and I'm just starting to poke around.

  2. #2

    dtravis7's Avatar
    Member Since
    Jan 04, 2005
    Location
    Modesto, Ca.
    Posts
    28,899
    Specs:
    iMac 2010 27" QuadI7 OSX10.11, iMac 2008 OSX10.11, MBP Late2011OSX10.11 , iPad Air, iPhone 3GS
    Are the drives plugged directly into the iMac and not Via a USB Hub?

  3. #3


    Member Since
    May 03, 2011
    Posts
    3
    They were plugged in via USB hub.

  4. #4

    dtravis7's Avatar
    Member Since
    Jan 04, 2005
    Location
    Modesto, Ca.
    Posts
    28,899
    Specs:
    iMac 2010 27" QuadI7 OSX10.11, iMac 2008 OSX10.11, MBP Late2011OSX10.11 , iPad Air, iPhone 3GS
    Reason I asked is I have recently had issues like yours and one of my 7 port USB Hubs was causing everything plugged into it to drop. Went to the other hub nothing so far.

  5. #5


    Member Since
    May 03, 2011
    Posts
    3
    I'll keep that in mind as a possible cause. I have other, less-sensitive USB devices (printers, scanner) that I'll plug into the hub instead. The problem was so bad that I gave up on Time Machine and bought a copy of SuperDuper. It's not necessarily the kind of backup I want on a regular basis, but it seems to be capable of stopping the drop out from occurring. Is there a fundamental reason that the hub might cause a problem? If not, I could also buy another hub. (I know the problem was not caused by an accidental disconnect.)

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