Changing partition size in external HD

I have my hard drive partitioned to use it with Time Machine and also use it for storing files. I want to change the size of the partitions. I've researched this a little bit... and I think I need to create a disc image of the partition. Then I have to wipe the drive clean and I can install the .dmg

I've never created my own .dmg so I want to make sure before I go ahead with anything.

You don't have to create a disk image or wipe the drive clean.

1. Attach the external hard drive to your computer and open Disk Utility from Applications, Utilities. Your external drive along with your MacIntosh HD and DVD drive should be showing on the left side in Disk Utility.

2. Highlight the external drive (where it gives the size of the drive) and then click on the "Partition" tab. You should see a box that says: "Volume Scheme". The scheme should say "current" and it will show one large partition.

3. Click the down arrow and select "2 partitions". Two partitions will appear. With your mouse drag the separator line until you have divided the partitions the way you desire. (It will show how much space for each to the right as you drag the line.) When you're satisfied, click "Apply".

You now have two partitions and your data (depends on how much you had on the drive) should still be intact.

Regards.

I've followed your directions, except I cannot bring myself to click the "apply" button. It seems like it will be creating 2 new entirely new partitions. The new partitions are called "Untitled 1" and "Untitled 2" and it just seems like they might not retain my files since they have to be renamed. I just can't afford to lose anything I have in my partition. Is there a way I can back up my drive just to be safe?

By all means make a backup first. You should backup whenever making changes to a drive's partition scheme or file system. Easiest way to backup that drive is to clone it to another drive. That means you need another external drive large enough to hold your data.

Also, don't forget to "name" your partitions before setting them.

Regards.