External Hard Drive won't mount on iMac

Discussion in 'Mac Basics and Help' started by pup73, May 24, 2013.

  1. pup73 macrumors newbie

    May 24, 2013
    hi everyone. here is my problem:

    i have a 27inch iMac. i recently purchased a Seagate backup plus 4TB external hard drive to use as my Lightroom file source. I formatted it using disk utilities in EXFAT format. I immediately copied around 1TB of data onto it. Used the drive all day yesterday with no issues. Went to sleep. I did not shut down my Mac (i normally don't). When i went to use the computer this morning, it wouldn't start up. So i did a hard start (is that what it's called? i just held down the power button until it booted up). Now my external drive won't mount. I've tried all the USB slots, I've reset PRAM, etc.

    The external drive does mount and is recognized by my laptop PC. all my files are there. But i can't get it to mount on my iMac.

    I assume this was a problem dismounting, when i hard reset my iMac?

    How can I fix this, and how can i prevent it.

    Please help!

    thanks in advance

  2. justperry macrumors G3


    Aug 10, 2007
    In the core of a black hole.
    Connect it to the Mac, open Disk Utilities, click on the HD and repair it.
  3. blueroom macrumors 603


    Feb 15, 2009
    Toronto, Canada
    How are you backing up the 4TB drive? or is that important? In my experience unplugging and plugging USB storage (any kind) will eventually cause data corruption, even if you're careful. ExFAT is handy but not robust.

    If you're regularly sharing between a PC and Mac would a GigE NAS be a possible? You could use the 4TB as an external backup to the NAS and as an added bonus a good NAS will also function as a TM backup for the Mac and a network backup for the PC.
  4. pup73 thread starter macrumors newbie

    May 24, 2013
    The problem was the HD was being recognized by Disk Utilities..


    well, i'm not quite sure how, but my HD is now mounting. I did an SMC reset and PRAM reset twice, changed USB ports and now the disk is mounting.

    in regards to the 4TB drive, my issue is it has an external power supply, but does not have a power on/off feature. i'm not sure how best to approach this issue. i normally don't power down my mac. should i just keep the 4tb external drive powered on at all times? should i drag it to the trash, so it's safely ejected, then unplug it when not it use?


  5. Fishrrman macrumors G5


    Feb 20, 2009
    "in regards to the 4TB drive, my issue is it has an external power supply, but does not have a power on/off feature. i'm not sure how best to approach this issue."

    This is one of my biggest gripes with "pre-assembled" external hard drives (and why I don't buy them, myself) -- no power switch!

    In my case, I have a Seagate 1tb firewire external drive (was given to me, I didn't buy it). Again, no power switch. I don't want it powered on all the time, and since I only use it for occassional backups, I don't need the drive icon on my desktop at all times.

    But no way to shut it off!

    I _do_ keep an 8-port surge protector at my desk, down at floor level. The Seagate drive has a power block, so I leave the closest socket on the surge protector "open", with the power block next to it.

    When I need to use the drive, I just plug in the power block, and the drive "comes alive" and mounts on the desktop.

    When I'm done with the backups, I drag the drive icons to the trash to dismount them, then pull the power block out of the socket.

    It's downright clunky, but really the only option available.
    It works….

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