How do I repartition an external hard drive?

[Minxy]

Hi.
I'm using a MacBook Air and external Hard Drive which is broken up into three partitions, a Mac partition, PC, and Time Capsule/backup.

The Mac partition is almost full and so I would like to move some of the available space from PC drive to Mac drive without loosing any of the data I already have on each partition. In the past when using Windows I used a program called Partition Magic. I've had a look at Disk Utility in OSX but wasn't sure if it could do it.

Any ideas if this can be or how it can be done? Preferably a free option.

Thanks

 

[MacUser2525]

Well totally depends on the partitioning you have in place now. If you have mbr partitioned drive then your only choice is to try the partition magic and hope for the best. GPT partitioned drive then Disk Utility can resize the partitions but that can be tricky depending on the layout you now have in place. For instance partition one mac, partition two pc and three TM. You can use Disk Utility to delete the number two grab the diagonal lines in the corner on one to make it larger then click on the rest of the blank space then plus option to give you a number two partition back once you apply the changes. Any other layout than that and I am failing to see the sequence to get that done without all kinds of extra backup space needed. As it is you would need enough backup space to hold the pc files when doing first scenario.

Edit: Actually one being TM, two mac, three pc can work as well.

 

[Fishrrman]

If nothing else works, you can "do it the long way".
It will take more time, but it WILL accomplish your goal.

That is:
BACK UP everything to other drives.
RE-initialize the drive.
RE-partition it as desired, then...
Restore all the data to the new partitions.