My external HD works on one computer and not another. why?

Discussion in 'Mac Accessories' started by oxband, Jul 21, 2011.

  1. oxband macrumors 6502

    Joined:
    Sep 10, 2009
    #1
    So, I have this two year old 320GB toshiba external HD. It works with a USB cable.

    When I plug it into my MBP (from 2009) it works. When I plug it into my MacBook from 2007, the light on it comes on but I cant' mount it. I've opened Disc Utility and I dont ever see it there.

    How can I fix this? Any thoughts? I have used other portable external HD's on that MacBook so I'm not sure how to solve this problem.
     
  2. DewGuy1999 macrumors 68040

    DewGuy1999

    Joined:
    Jan 25, 2009
    #2
    It's possible that the MacBook does not provide enough power through USB to power the drive. Have you tried all the USB ports, sometimes one provides more power. If that doesn't work some hard drive companies have a Y cable that plugs into the hard drive and 2 USB ports to provide enough power, maybe Toshiba has one.
     
  3. AppleDApp macrumors 68020

    AppleDApp

    Joined:
    Jun 21, 2011
    #3
    What file system is the external hard drive using? what OS is on each machine?
     
  4. oxband thread starter macrumors 6502

    Joined:
    Sep 10, 2009
    #4
    I'm running 10.6.8 on both computers. The external is Mac OS Extended.
     
  5. AppleDApp macrumors 68020

    AppleDApp

    Joined:
    Jun 21, 2011
    #5
    Have you tried all the ports on the 2007 mac? maybe use a hub.
     
  6. bodgerx macrumors newbie

    Joined:
    Feb 14, 2008
    #6
    Apologies for bringing this thread back from the dead, but I have the same problem.

    It is Lacie Rugged USB drive. It worked fine on my iMac with 10.5 on it, until one day I plugged it and it didn't even show up in the finder. Disk Utility failed to find it also. Plugged it into other Macs with 10.5 and it worked fine. I then upgraded the iMac to 10.6 - no difference to the drive.

    Upgraded to a Macbook Pro i5 with 10.6. Initially, fresh out the box, the drive worked. But, rather than use the MacBook Pro clean out of the box, I took the time machine backup (on another firewire Seagate drive) from my iMac with all my stuff on it, put the Macbook Pro into target disk mode and 'restored' everything from my iMac to the Macbook Pro. As soon as I did this the Macbook Pro stopped recognising the Lacie disk.

    It is as if my iMac (and its backup image) has 'marked' the Lacie drive as bad and now refuses to mount it. This 'setting' has now transferred to the Macbook Pro. Short of reinstalling everything from scratch on the Macbook Pro can anything be done to get it to recognise the drive again?

    It still works on other macs I've tried it on....

    Strange...
     
  7. Fishrrman macrumors G4

    Fishrrman

    Joined:
    Feb 20, 2009
    #7
    "It's possible that the MacBook does not provide enough power through USB to power the drive. Have you tried all the USB ports, sometimes one provides more power. If that doesn't work some hard drive companies have a Y cable that plugs into the hard drive and 2 USB ports to provide enough power, maybe Toshiba has one."

    The above reply is correct.

    The older MacBook isn't supplying enough bus power to get the drive "up and running". It might seem to get "halfway there", but never completely spins up and mounts.

    The solutions:
    - Get a Y-cable (as mentioned in reply 2), and see if that works
    - Get an external power source for the drive's enclosure (some drives have an input jack for external power, but others don't)
    - Take the drive OUT of the enclosure, and use it with a USB/SATA "dock" such as these:
    http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias=aps&field-keywords=usb+sata+dock&x=0&y=0
    (many items shown, they all work the same, just pick one you like that's cheap)
     
  8. DewGuy1999 macrumors 68040

    DewGuy1999

    Joined:
    Jan 25, 2009
    #8
    Does it show any signs of life, like an activity light?
     
  9. bodgerx macrumors newbie

    Joined:
    Feb 14, 2008
    #9
    For me that doesn't apply. It is the iMac that it doesn't work on. It was fine to start with then all of a sudden it wouldn't mount.

    Tried it an a range of other macs (both iMac and Macbook) and it works fine.

    Changed to a new Macbook Pro, initially, it worked fine. As soon as I restored the system from my iMac to the new Macbook, then the Macbook stops recognising the drive - as if it has transferred this 'bad disk marker' knowledge about the drive across to the Macbook.

    My guess is that if I start again with the Macbook, and wipe it, the drive will be fine. Don't want to do that though.

    ----------

    You can hear it whirring, so its powered. Physically, its fine. It works on every single PC/mac I've tried it on, except the iMac and then after i copied the system to the Macbook Pro.
     
  10. DewGuy1999 macrumors 68040

    DewGuy1999

    Joined:
    Jan 25, 2009
    #10
    See if this discussion might be helpful:

    'NO ACCESS' External Hard Drive in Ownership & Permissions
     

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