Why won’t Windows recognize an MacOS partitioned external hard drive?

Clayton U August 14, 2013
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My wife has an iMac with OS X Lion on it. We partitioned her HD to run bootcamp with Windows 7 to play some games. Bought a Seagate Backup Plus external USB HD for extra space for games on the Windows 7 end and Time Machine for her iMac. Time Machine does not work with the Paragon driver the ext HD came with so I decided to partition it into two parts; one for Mac, the other for Windows.

I looked up about the different HD formats for Mac and Windows. Used Disk Utility to partition the ext HD 50/50. Named the top partition Mac and chose the format Mac OS Extended (Journaled), named the bottom Windows and chose the format NTSF.

After running Time Machine on the Mac partition I restarted the iMac to Windows 7. I did not eject and unplug the ext HD before restarting, not sure if it played into my problem or not but thought I’d mention.

Once Windows 7 started I opened up My Computer and I did not see the ext HD listed. I ran Disk Management and saw the ext HD listed but it did not show any partitions. Just shows the entire ext HD unallocated.

What do I need to do in order for Windows to see the necessary partition?

Been reading up on the different “options” for the partitions; i.e. GUID and MBR.

  1. Clayton U
    August 15, 2013 at 7:09 pm


    I originally read that link you provided before I was having the issues. I solved the problem yesterday. I changed the Windows partition on the external HD to MS-DOS, ejected the HD, rebooted into Windows 7, plugged in the HD, Windows saw HD right away, went into Disk Management and changed the Windows partition from MS-DOS to NTSF.

    Thanks for everyone's help.

    • Hovsep A
      August 16, 2013 at 12:50 pm

      Thanks for your feedback:) your valuable solution will help others:)

  2. Justin Pot
    August 15, 2013 at 4:17 pm

    Did you install the Bootcamp tools after installing Windows? Because that's essential if you want to see these drives. Simple thing, I know, but I thought I'd check.

  3. Jan F
    August 15, 2013 at 6:56 am

    I am a bit surprised you are having issues because your iMac and OS X version suggests that the drive is most likely formatted using the GUID/GPT partition scheme which Windows 7 should have no issues with reading.

    Actually, being curious I just tested it with Lion and Windows 7 (no bootcamp):
    I partitioned a drive with one OS X Extended partition, one ExFAT using the GUID partition scheme and Windows detected the ExFAT partition right away.

    Maybe it's a derp from bootcamp? Anyway, the options you were reading up on are most likely the solution to your problem.

    Since you only used Time Machine so far and Windows couldn't even access the drive I assume you have no problem with formatting the drive again losing all data currently stored on it?

    Go into Disk Utility, select the external drive and click on the partition tab.
    Select 2 partitions etc. as you did before ~ OS X Extended for Time Machine, ExFAT or Free space for Windows. At the bottom click options and select "Master Boot Record". Then finally apply the settings and let the drive partition.

    Maybe bootcamp only likes MBR partitions ~ hope this solves your issue.

  4. Hovsep A
    August 14, 2013 at 8:47 pm

    have you tried to use windows restore point to revert back just before the problem started?

    How to view HFS+ hard drives from Windows

    • Clayton U
      August 14, 2013 at 9:05 pm

      Not quite what I am asking.

      Bought the external HD because it is compatible with Mac and Windows because of the pre-installed Paragon driver (allowing Mac to read and write on NTSF). However, there was a note saying Time Machine wouldn't be able to be used. So I reformatted the external HD.

      I'm wanting to know why the partitioned disk is not showing up in My Computer. In Disk Management the entire external HD is unallocated. Only option when right clicking not grayed out is to format it.

    • Hovsep A
      August 14, 2013 at 9:33 pm

      how you reformatted the external hard drive? which file systel

      The best ways to format an external drive for Windows and Mac

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