recently i installed windows 7 along with mac OS X Yosemite(using bootcamp).Now i have two partitions one for mac and one for windows.

Now Can i split the windows partition in to two partitions without loosing any of my OSs.


No !
Don't ever let Windows touch the partitioning.
Tears will ensue.
It simply does not understand how Boot Camp has fooled it into believing it's on an MBR disk.

Disk Utility will not let you add a new Partition either. 4 is your max without some very tricky Terminal juggling. I'd leave it alone unless you are very confident in Terminal.

iPartition is really the only app that could do it, but has major limitations if you are using Core Storage.


You may be able to do it using a combination of tools:

  • GParted -- This Linux tool should enable you to shrink the Windows partition and create a new one in the free space. It will, however, wipe out the hybrid MBR that your system probably relies upon to enable Windows to boot. If you don't normally run Linux, you could run GParted from an Ubuntu installation disk (select the option to try it before installing) or some other Linux emergency tool.
  • gptsync -- This EFI program, which comes with rEFIt and rEFInd, can create a new hybrid MBR. Note that the rEFInd version is significantly updated and "smarter," which might or might not be necessary given your needs. To launch it from rEFInd, you must fiddle with rEFInd's configuration, since hybrid MBRs are ugly and dangerous and I didn't want users creating hybrid MBRs by mistake. (I maintain rEFInd.)
  • gdisk -- This program, which is available for Linux, OS X, and Windows, should be able to create a new hybrid MBR. It's much more flexible than gptsync, which makes it more capable; but it's also important that you understand what you're doing if you use it. Note that I wrote gdisk.

There may be other tools that can perform one or both of these tasks, but I'm not familiar with them. Tetsujin is quite correct to warn against using the standard Windows partitioning tool for the job; it will act on the MBR side and ignore the GPT site, which is likely to lead to disaster.

In sum, you should be able to use GParted and either gptsync or gdisk to do what you want. Be VERY cautious, though. Read up on the subject (start with my page on hybrid MBRs) and back up all your important data before you begin. If you have any doubts about the process, don't do it! Resizing partitions on a hybrid MBR disk is possible, but it's also extremely dangerous, so a mistaken understanding of how it's working is likely to lead to disaster.

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