How to create NTFS data partition that can be seen from OS X and W7

[churin]

I am a long time user of Windows machine and recently I added an Apple machine. It is MB Air with 250GB SSD. I installed W7 using the Bootcamp assistant. In the process 100GB was allocated to the OS X and W7 was installed on the remaining 150GB. W7 worked just fine and I could switch between the two OSes.

On my Windows machine I always create partition(s) for data storage. To follow this practice, I created a separate partition out of the Bootcamp partition(W7 partition). This is where my present problem happened.

By using iPartition, I shrunk the W7 partition to 60GB and left the remainder as an unallocated space. Then after switching to W7, a data partition was created using the 90GB unallocated space. Problem: The data partition was not shown on the OS X.

I tried creating data partition differently: This time I used iPartition to create the NTFS data partition. Problem: The data partition was not shown on W7.

Is there a way to create a NTFS partition which can be seen both from OS X and W7? I am aware of read/write issue even if the partition is seen but I know the solution.

 

[Dr McKay]

Format the partition in exFAT (Also known as FAT64). The latest version of Windows Vista and Windows 7 will be able to read and write to it, and also Snow Leopard.

Just make sure you format it from Windows 7, that way both OS's will be able to read & write to it, Ive heard any exFAT formats done on OS X wont be readable on Windows.

 

[churin]

Please note that the issue is that the partition is not seen as valid drive and not about ability to read/write on it. If it is created on OS X, W7 cannot see it, and if it is done on W7, then the OS X cannot.

Do you mean that if it is created in exFAT on W7, it will be seen on OS X ? If so, what third party software to use to do it, since W7's built-in utility allows only NTFS or FAT32?

 

[Quad5Ny]

The data partition is probably not showing up on Windows 7 because it has not been updated on one of the partition tables.


Apple computers use a GUID Partition Table (GPT) but most of the time Windows will only let you install on a Master Boot Record. So to do this the Boot Camp Assistant overwrites the Protective MBR and creates a Hybrid MBR in its place which stores the first 4 partition entry's.

Windows does not have access to updating the GPT, which is why it did not show up on OS X after you created it (it only updated the Hybrid MBR). And on the other side iPartition might have not updated the Hybrid MBR (Either that or maybe it just didn't format it. You did check to see if the new partition was Formatted, right?)


Anyway I think the solution to this would be to use the Partition Sync tool in rEFIt. It should (hopefully) take care of updating the Partition Tables. Please remember to backup your data before doing this.

 

[churin]

I dabbled with rEFIt and saw the following but do not know what to do with it. Present situation is that the partition is created by W7 so that OS X cannot see it.

 

[Quad5Ny]

For some reason you have a Extended/Logical partition. OS X can only read from Primary partitions.

Seeing as you only have 4 partitions, follow these instructions:

1. Go into Windows & launch Computer Management (Start > Type "compmgmt.msc" > Press Enter)
2. Click "Disk Management" on the left
3. On your HD you should see a Blue Partition (This is a Logical Partition residing inside a Extended Partition)
4. Right Click on it and choose "Delete Volume"
5. It will turn Green (This is Extended Partition Free Space)
6. Right Click on it again and Choose "Delete Partition" (There should now be a block of Black Free Space)
7. Open a Elevated Command Prompt (Start > Type "cmd" > Right click on cmd> Choose "Run as administrator")
8. Type "diskpart" & Press Enter
9. Type "list disk" & Press Enter
10. Type "select disk 0" & Press Enter (I'm guessing 0 is the HD OS X/Windows is on. If its a different one, refer to the output from "list disk")
11. Type "create partition primary" & Press Enter
12. Type "exit" & Press Enter
13. Close the Command Prompt
14. Find your newly created partition in Computer Management
15. Right Click on it and choose "Change Drive Letter and Paths..."
16. Click "Add", Choose a Letter then Click OK
17. The Format Box should now popup (I recommend NTFS or exFAT w/ Allocation unit size set to "Default allocation size" & "Quick Format Checked")
18. Click "Start" and Let it Format (Creating a File System)
19. Close Computer Management
20. Restart & Launch the rEFIt Partition Sync Tool

After everything is working you can either keep or Uninstall rEFIt.

Remember backup your data in case I made a mistake or something goes wrong.

 

[churin]

I followed the instructions but the data partition so created still did not show up on the OS X.

The rEFIt used was one for OS X and booted from the CD. I do not know if this is anything to do with my present problem.

On the rEFIt, I responded by entering Yes to the proposed change as below.
If I should start over, I wonder what should be the correct steps to take after creating the Bootcamp partition which means installing W7.