Any partition software just to partition unused space? Currently I have one portable external hard drive which I use for Windows. It's 1TB and over 300GB is used space. I would like to partition it so I can access the unused space from my Mac. Can you all recommend any partition software which does the job? I am afraid that it would wipe out my current data that's why.
You can use Partition Magic in Windows and divide hard on two virtual hard disks. And then use one for Mac and one for Win.

And for Mac and Win can work at one hard drive, just reformat a hard drive to FAT32.

If you don't want format your hard drive:


Open Partition Magic
Create a second virtual hard drive on free space. Recommended percent: 50% on 50%
Reformat second virtual hard drive to FAT32