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Boot Camp isn't officially compatible with 3 TB hard disks. If you have a 3 TB hard disk, you can install Windows with this trick > http://www.twocanoes.com/support/winclone/installing-windows-via-boot-camp-on-a- large-(2.2-tb-or-larger-)-drive-in-lion-(10.7)-and-later
If you have a 3 TB Fusion Drive, it's not possible at the moment
Sorry to open an old thread but I need help. I have attempted to follow the instructions set forth by twocanoes.com. I just purchased my new 27" iMac with a 3 TB HDD. Well as we already know, that is the root of the problem. But I encountered a secondary issue. When attempting to create a 3rd partion (creating 3 1TB partions as told to do so by the instruction) I am only able to make 1 partion. I only have the option to remove it. I cannot add 2nd partion to make my 3 equal partions. Can someone please direct me to a resolution to create my third partion.
From what I have already looked up it is an issue relating to Lion.