How to format unallocated space

Discussion in 'OS X Mountain Lion (10.8)' started by Plineo, Jan 23, 2013.

  1. Plineo, Jan 23, 2013
    Last edited: Jan 23, 2013

    Plineo macrumors newbie

    Jan 4, 2013
    Murcia, Spain

    I'm new with Mac OS X and I have an external USB 1 TB HDD that I want to use with Time Machine. This hdd had 2 partitions 500 GB each, formatted in NTFS, because I used with Windows. While my new iMac was comming home, I decided to get ready to use the external hdd so I repartitioned the HDD. I erased first partition in order to format it later with the iMac, and I formatted the second partition with exFAT.

    Now that I have my new iMac and the external hdd connected, I can access partition exFAT without problems, but I cannot format the unallocated space with Disk Util, what's more, I can't do anything on this, except repartition the whole disk. Do you know why?

    I know I can connect the hdd to a Windows machine, format the space with whichever format and then in Mac OS X, erase and reformat in HFS+, but why??
  2. timme macrumors newbie


    Aug 13, 2014
    same problem

    i have this with my main harddisk of 3 tb... do i have to repartition the whole disk? and then restore it with time machine?

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