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I installed Snow Leopard on my Macbook Pro. I then installed Windows 7 in a Boot Camp partition. Then using Windows 7's disk management console, I resized my Windows 7partition and created a 3rd NTFS partition for data, intending for both Windows 7 and Snow Leopard to read/write this partition.

I installed MacFuse and NTFS-3G in Snow Leopard, but Snow Leopard still shows I have a single Windows 7 partition. How can I get Snow Leopard to recognize my third partition?

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Is this 3'rd partition (still) visible to Windows 7? What does the Window's 7 Disk Manager show? Since Window 7 is GPT aware it should have updated the GPT. However, perhaps the hybrid MBR created by OS X Boot Camp confused the Windows 7 partition tool? – irrational John Jun 20 '10 at 2:20
yes, I had no trouble read/writing to the 3rd partition from Win7. I've since scrapped this setup though and not running SL at all anymore, so I don't have any additional details to provide. thanks for contributing though – kenwarner Jun 21 '10 at 14:34

Windows and Snow Leopard use different areas of the HD to store the partition layout (in fact there are three ways, OS X EFI, MS-DOS Bootsector and Vista/Win7 EFI). If you create a partition from Windows it will not make it's way into layout table of OS X.

Try a Mac software named EFIXIT. It has a feature to synch the different types. I'm not entirely sure if it can sync back from Windows to OS X, but if you create the extra partition under OS X it can sync the new partition into Windows.

(I have done a 3-Partition layout in the past. However, my sequence was: Install Windows on Bootcamp Partition, then on the Mac shrink the Mac parition (using DiskUtil), create a new partition, use EFIXIT to sync it and format it with FAT32).

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where is this efixit software? – kenwarner Mar 3 '10 at 22:05
sorry, got the name wrong ... it's called REFIT (or part of the REFIT software) – Nicholaz Mar 4 '10 at 10:59

In addition to Nicholaz's answer, it is worth noting that for a partition to be read/write capable in both Windows and OS X, it must should be formatted in FAT32, as it is common to both OS's. Unless you plan to install third party software (which in my experience is unstable), OS X is incapable of writing to NTFS partitions.

Newer versions Mac OS X are capable of reading and writing to the legacy FAT file systems(16 & 32). They are capable of reading, but not writing to the NTFS file system. Third party software is still necessary to write to the NTFS file system under Snow Leopard 10.6.4.

Quote taken from Wikipedia on File Systems

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