Sharing Data between Windows and OSX Leopard

Hi, I created a how-to for creating a 3rd Data partition for the purpose of sharing data between OSX Leopard and Windows using Boot Camp. I thought I'd share it with everyone here.

The only downside is that this 3rd partition has to be formatted as FAT32. You can format your Windows partition in NTFS, which may or may not preserve performance. Perhaps someone with more knowledge about these things can chime in...

What you'll Need

-An Intel Mac
-Mac OSX Leopard & your Mac OSX Leopard installation disc 1 (for Boot Camp and Disk Utility)
-Windows XP SP2 or Vista (I used XP SP2 in the making of this tutorial)

Preparation

Decide How to Partition your drive:

We'll be splitting your total hard drive space into 3 partitions. One for Mac OSX Leopard, one for Windows, and one for your shared Data. It is easiest to complete this process with a brand new computer, but it can be completed if you are already running Boot Camp with Windows on your Mac. You will be stuck with the partition sizes you've already chosen unless you choose to resize your Windows partition.

If you are starting fresh, though, you'll have the opportunity to decide what size you want each of those partitions to be. This is an important decision because once you determine the partition sizes, it can be at best annoying and at worst difficult or impossible to change them (unless you are willing to delete everything and start from scratch).

Your decision will depend on the total size of your hard drive and the amount of software you use on each operating system. For example, if you use your Mac operating system for all computing and use Windows only for a one or two things, you can create a Windows partition that is relatively small compared to the Mac partition. Keep in mind that if you make your partition too small, there will not be enough room to install all the software you need, but if you make it too big, then you leave less room for your shared data.

Generally, you'll want to leave the most room for your Data partition: documents, videos, music, etc. These tend to take up the most hard drive space, and they are the kinds of things you'll want to share between the operating systems.

I would recommend a minimum of 15 gigabytes for each operating system. More if you install a lot of big software programs. I use both the Mac and PC operating systems equally, and my hard drive is 160GB, so I have decided to partition my hard drive as follows:

-Mac OS X Leopard: 30GB
-Data: 100 GB
-Windows XP SP2: 30 GB

Step 1: Backup!

If you have ANY important data on your computer (favorite song, youtube video, Antics project, email from Aunt Helen), back it up, because it might not be there at the end of this process.

Step 2: Install Mac OSX Leopard

This one will be easy for most of you, as it's already done! But if you have Mac OSX Tiger currently, or if you are wiping your computer to start from scratch, start by installing Mac OSX Leopard. At this point, your hard drive should still be one big partition. (If you have already installed Boot Camp and Windows, read on)

Step 3: Use Boot Camp to install Windows

You will follow the same process here as a normal Boot Camp installation, except that you will pay close attention to the partition size you create for Windows. Create the partition size (for Windows) that you decided in the preparation stage. In my case, that means I'll create a 30 GB partition for Windows, and the rest of the disc space will stay in the Mac partition (for now).

If you had already partitioned your hard drive using Boot Camp before you read this tutorial and you now want to resize your Windows partition, you should do it before you proceed to the next step. Once you move onto the next step, you are finalizing the partition size you have chosen for Windows.

Step 4: Edit the Windows boot file

You'll have to edit the boot.ini file in Windows so it will know which partition to boot from. In the next step, we will add a Data partition, which will render Windows unbootable if we don't make this change. Please be sure to make only the change specified. If this file is altered erroneously, it could render Windows unbootable, and you'll have to redo the Windows installation.

In Windows XP (if you're using Vista, this process might be a little different... I haven't tried it with Vista yet), Right click on 'My Computer' and choose 'Properties'. In the 'Advanced' tab, choose the 'Settings' button under 'Startup and Recovery'. Choose the 'Edit' button and carefully proceed. Your boot.ini file should look something like this:

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(3)WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(3)WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect

You'll notice that (3) appears twice. We are going to change each (3) to (4) so your boot.ini file will look something like this:

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(4)WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(4)WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect

Note: This text is only meant to illustrate the change. Please DO NOT copy and paste it into your boot.ini file, as yours may have small but vital differences.

Save your changes, and complete any business you have in Windows. You will not be able to boot back into Windows until we have completed the rest of this process.

Step 5: Create your shared data partition

Boot from your Mac OSX (Leopard) Install Disc 1. Hold down ‘c’ during startup to boot from the disc.

Choose ‘English’ and click the arrow in the lower right to continue.

DO NOT click on ‘Continue’ in the Welcome window. Wait for the finder bar to appear on the top of your screen and choose 'Utilities > Disk Utility'.

In the white space on the left of the Disk Utility Window, click on your hard drive (not the Mac or Windows sub-partition, but on the hard drive itself), and choose the 'Partition' tab.

Beneath ‘Volume Scheme’ you will see the current partition structure of your hard drive. If all has gone well, there should be a ‘Macintosh HD’ partition and your Windows partition (probably labeled ‘disk0s3’).

Click on your Mac partition and you will see information about that partition, including an editable ‘Size’ field. Change the Mac partition size to the size you chose during preparation by keying in the amount in gigabytes. In my case, that would mean 30 GB. Apply your change (Note: As this utility is running from a disc, it may be slow to respond to your keystrokes).

Once you have successfully shrunk your Mac partition, there will be free space available on your hard drive. Click on the free space and allow the size to be autofilled by the partitioning utility, as it will default to the remaining space available. In the two fields just above Size, BE SURE to change the Data partition’s ‘Format’ field to’ MS-DOS (FAT)’, as this is the only format that both Windows and Mac can share. In addition, change the ‘Name’ field to ‘Data’. Apply your changes, quit, and turn off your computer.

Step 6 (Optional): Test data sharing between Windows and Mac

Start up the computer and hold down the option key to invoke the Boot Camp boot manager. Choose Windows. Once you boot into Windows, double click on 'My Computer', and you will see that a new drive is available. It is labeled 'Data' and will have its own drive letter (usually D or E). Save a test document (.txt format is good for testing) in your new drive. Restart into Mac OSX, and you will see your Data drive available on your Mac desktop. Check to see if you can open, edit, and save changes to your test document. Restart into Windows, and check that you can see the changes, edit, and save new changes. You have just completed your computer's first Windows/Mac data sharing experience.

In the future, be sure to save all your music, videos, documents, and other data to your shared ‘Data’ drive so you will have access to them from both operating systems.

Step 7 (Optional): Move your 'Documents' folder to your shared drive

You may wish to move your ‘Documents’ folder on both operating systems to a folder on your shared drive, so your computer will save data there by default.

In Windows, right click on ‘My Documents’, choose ‘Properties’, then click on ‘Move’ to browse to the documents folder you created on your shared drive. Be sure to Apply your changes before closing the window.

In Mac OSX Leopard, Go to Apple Menu > System Preferences > Accounts. Make sure your account settings are unlocked for editing and control-click on your username. Choose ‘Account Settings’. Next to ‘Home Directory’, click on ‘Choose’ to browse to the documents folder you created on your shared drive. Click OK when you are done.