Sharing external hard drive between Windows and Mac, airport extreme
The advice above is correct if you want to divide your hard drive into two parts, one for windows and one for mac. Or create one big Exfat partition that both computers can use. Plug the hard drive directly into your computer to use time machine with exfat.
I was interested in doing something like what you described above, but I wanted to create my backups over my home network using a drive connected to my airport extreme router.
(
airport and time machine: ExFAT and NTFS formats aren't supported).
Here is what has worked for me:
Mac
1. Format the Drive on my Mac using disk utility set to "Mac OS Extended with Journaling"
2. Plug that Drive into the USB port on my airport extreme.
3. Set Time Machine to automatically back up my mac on that drive.
Windows:
1. Installed the free program HFSExplorer
http://catacombae.org/hfsx.html
to allow Windows 7 to read the Mac partition on that hard drive.
2. Save files manually to that disk or search for a program to create automatic backups.
Windows 7 Home premium now sees my mac drive plugged in to the airport, and to my surprise is able to save files to that drive as well.
Windows backup did not recognize that drive as a valid backup destination, but for now I'm happy enough with the ability to manually save files and share them between either computer.
I'll look for another backup program later to try to automatically backup windows files to the airport drive.