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PAL1963 Level 1 Level 1

my mac does not see my external hard drive

iMac, OS X Mountain Lion (10.8.1)
  • Kenichi Watanabe Level 8 Level 8

    Run Disk Utility.  Does the external drive appear in the Disk Utility sidebar, in any way?

  • PAL1963 Level 1 Level 1

    No it does not show up in the disk utility

  • Kenichi Watanabe Level 8 Level 8

    Did this drive work with this Mac before, and does not work now for some reason?  Or is this the first time you are trying to connect this drive to this Mac?


    If you have not already since having this problem, shut down (power off) and then power up your iMac.  If the external drive has a power swtich, also turn it off and back on when you do this.


    You'll need to rule out possible causes...


    If you have another external drive (or something similar like a USB flash drive or iPod), connect it to the same USB port.  If it works, then the USB port on computer is probably fine.


    Try another USB cable, if you have one, in case the cable is bad.


    If the drive connects using FireWire, most FireWire drives also have USB, so try connecting it using USB.


    You should also shut down and try disconnecting all other USB (and/or FireWire) devices, except for standard USB keyboard and mouse (if used).  Start up the Mac and connect the external drive to a direct port on the Mac.  This will check for a device conflict, or a faulty device, that is interfering with your external drive.

  • sunitakharel Level 1 Level 1

    thank you kenichi, it helped me as well.

  • Jenna.chou Level 1 Level 1

    no not for me!  i am a new mac user and i have tested ALL ports on both MacPro 13" and my other netbooks that's windows based.  It detects fine on windows OS but when i plug it into the MacPro nothing shows up under DEVICES. 


    I am trying to transfer files on my I/O Magic 500GB external harddrive onto MacPro so I can reformat my other window based computer....


    i called AppleCare and the tech said that it's most likely the format of the external harddrive is not set up to be used on the Mac, since this is the first time I plugged the external drive into a Apple Device. 


    So what do I do now?  ALl of my external USB sticks (4GB, 8GB, 32GB) all work and I can see them under DEVICES in Finder.  My mini 32GB SD card also is detected by MacPro automatically. 


    I have like 350-500GB worth of stuff on my external I/O Magic harddrive and I don't think transferring one folder at a time onto UBS sticks is working out (which is exactly what I am doing right now)


    Please HELP!!!  Rookie MacPro user here!  (even though I have had iphone and ipad for yeras!  macPro is so different it takes time to get use to)


    thank you in advance for anyone who can please help me so i can transfer the files from external drive to the MacPro itself



  • Kenichi Watanabe Level 8 Level 8

    If it's 13", this is a MacBook Pro, correct?


    You did all the things in the previous post, including the one about disconnecting all other USB devices?  If this is a MacBook, you should also try it with the MacBook connected to its power adapter (instead of running off battery power).


    Do you know what disk format is used by that external drive?  If it's "FAT," Mac OS X should be able to read and write that format.  Those USB flash drives are probably formatted using FAT.  If it's formatted using "NTFS," Mac OS X should still be able to read it, although it will not be able to write to it.  If it's some other format, Mac OS X may not be able to access the drive.


    Do you still have your WIndows PC?  I'll assume you do, since you seem to be able to copy data to the USB flash drive. 


    If so, you can get another external drive that is at least the size of the data you need to transfer.  Make sure it is formatted using FAT, if it's not set up that way already, and make sure the MacBook can access it.  Copy your data from the old external drive to the new one.


    Or, you can try using a direct or network connection between the Windows PC and MacBook.  This document as information



    There is an automated process called Migration Assistant, but see Manual migrating to see how to set up a direct connection or network connection between Windows PC and Mac.

  • Jenna.chou Level 1 Level 1

    ok i just read the run disk utility post... which i just did.  I can see my external drive 'I/O Magic 500GB''.  now my HD is making some crazy sound not heard before when connected to win-based PCs. 


    i clicked on the partition tab and it's been the external has been blinking at me and making funny noises for few minutes now.  Ok now it's stopped.  I don't quite feel comfortable touching anything I have important documents on there I am afraid it will be erased (much like synching with iTunes is a one-way street and oh I have made that mistake before and lost all the files on my iphone before).


    You seem to know what you are doing and I have tried setting up a network before for all my PC's and Mac, I couldn't get it to work... like I said I am a rookie when it comes to MacPro and I have a few things I need support for setting up before I screw up and accidentally erase anything...


    Kinichi: Are you in North America?  Can you add me on Skype and maybe help me out?  I just reached the 3-months phone support so AppleCare technicians coudn't really help me but directed to this site which I believe you will solve my issues very easily. 

  • Kenichi Watanabe Level 8 Level 8

    Hopefully, you did not do anything to the drive on the Partition tab, such as Apply a new partition layout; that would reformat (erase) the hard drive.  Just going to the Partition tab does no harm.


    In the Disk Utility sidebar, do you see that external drive with a "volume" (disk) indented below the drive (device)?  If so, select that disk in the sidebar.  Down below (at the bottom of the window), what does it say for its Format?


    If you see a disk indented below the device in the Disk Utility sidebar, and its name is "greyed out," that means it is not currently mounted.  Try selecting it (the disk) in the sidebar, and clicking Mount (a button in the toolbar at the top of the window).  If that works, open a Finder window, and you may now see that disk under DEVICES in the Finder window sidebar.


    If you do not see any disk indented below the device (for the external drive) in the Disk Utility sidebar, it likely that your external drive is set up in a way that makes it not accessible from a Mac, unless you reformat (erase) it.  Then, you'll need to use another external device that is set up to be accessible from both a Mac and a Mac, or use a network connection.


    You can probably get in-person assistance at an Apple Store, if there is one nearby (and your Windows PC is also portable).  To do so, make a reservation at the Genius Bar using the store's web page



    (I don't use Skype.)

  • Lilian M. Level 1 Level 1


    I have a mac book air "13in, using Mac OS X Lion 10.7.5 and it does not recognize my 500GB samsung hardrive. It was recognized before and I used it both in PC and Mac and now the light on the HD does blink and the compurer seems like its processing something, but I cannot find it under devices anymore or any other place. The computer does not display any error messages either.

    The USB ports work fine and I also tried turning the computer on an off, as well as changing the cables, with no results.I cannot format this HD as I have family pictures and important documents there.

    I'm a rookie   Please help!

  • Kenichi Watanabe Level 8 Level 8

    It was recognized before and I used it both in PC and Mac

    It was recognize before with this MacBook Air, or on another Mac?


    Is it connected directly to the MacBook's USB port, and not through a USB hub?


    When you run Disk Utility, does it appear in the sidebar of Disk Utility in any way?


    If the MacBook was not connected to its power adapter, see if connecting it to the power adapter (so that it's not running off battery power), makes a difference.

  • Lilian M. Level 1 Level 1

    Hi Kenichi!


    Thank you for your promt and thorough response.


    The HD was recognized with this MacBook Air.


    It is connected directly to the MacBook's USB port.


    It took me a bit to find disk utility and it does appear on the side bar! It appears as a Samsung HD and also (separetly and below that) with the name I had given it. I click on the "Samsung" one and this is the info at the bottom of the window:

    Disc Description: Samsung S2 Portable Media

    Total Capacity: 500.11 GB (500,107,862,016 bytes)

    Connection Bus: USB

    Write Status: Read / Write

    Connection Type: External

    State S.M.A.R.T. : Incompatible

    USB Serial Number: 0000002CE0D70

    Partition Map Scheme: Master Boot Record (MBR)


    It does not give me the option to restore or to verify it


    AND when I click on the name I had given the HD it does give me the option to verify or restore it and this is the info at the bottom of the window:

    Mount Point: Not mounted

    Capacity: 500.11 GB (500,105,216,512 bytes)

    Format: MS-DOS (FAT32)

    Available: -

    Owners activated: -

    Space used: -

    Number of folders: -

    Number of files: -


    Is there any way to get the data in the HD back?


    Thank you once again.



  • Kenichi Watanabe Level 8 Level 8

    That sounds like it's working normally.  In the Disk Utility sidebar, Samsung S2 Portable Media is the "device."  Indented below the device is the "volume," which is the disk that appears in Finder (with the name you gave it when it was formatted).  The Mac's built-in drive should be listed in the sidebar similarly.


    So, I think you're probably not looking in the right place to "see" the hard drive.  Open a Finder window.  In the sidebar, look under DEVICES.  Does that external drive's disk (volume) appear there?  If so, click on it there to access it.


    If you want the disk to appear on the Desktop, in Finder, open its preferences.  On the General tab of Finder preferences, check the box for the types of items you want to see on the Desktop.


    If you don't see it, please post back.

  • Lilian M. Level 1 Level 1

    The HD does not appear in Finder under Devices.

    I changed the preferences in Finder so I can view devices on my desktop, still no success.


  • Kenichi Watanabe Level 8 Level 8

    Oh, in your previous post, I did not notice that it said

    Mount Point: Not mounted

    In Disk Utility, in the sidebar, the volume name (indented below the device) probably appears grayed out.  Select it in the sidebar of Disk Utility.  Near the top of the window, there is a row of buttons.  One of them says "Mount."  Click that button.  If it mounts, the name should no longer be grayed out and it should appear in Finder.


    It's possible that it will not mount, because it should mount automatically.  If the Mount command does not work, there may be some incompatibility or data corruption on the drive that prevents it from being mounted by the Mac OS X system.  You can try doing Verify Disk (on the First Aid tab).  If Verify Disk finds a problem, I would not do a Repair Disk at this point because that alters the disk, which is a risk.  You should transfer the data in some other way.

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