What's the secret to adding partitions in DU without erasing?

Not 100% sure, but I think they have to be formatted as Mac OS Extended (Journaled). Can you give some info about that?

partitioning with Disk Utility will erase all data on the drive...

to do a live "resize" you have to use a utility such as Partition Genius.

I'm old school and don't trust them... i tend to backup each partition, re-partition the drive, then copy data back to each partition.

http://www.spotmau.com/products/package/partition_genius.html

3rdfinger said:

partitioning with Disk Utility will erase all data on the drive...

to do a live "resize" you have to use a utility such as Partition Genius.

Click to expand...

Wrong. Leopard Disk Utility allows non-destructive partitioning of HFS+ partitions. Used it a number of times myself. A Boot Camp partition, though, will make the issue moot. That make all utilities fairly useless and a multi-step process of cloning, deleting, repartitioning, and restoring is needed.

Vader said:

I want to add a few partitions temporarily to one of my external HDs. In Disk Utility, my boot drive gets a "+" option to add a partition without erasing, but my other two drives have the option grayed out. Does it have something to do with having leopard installed on the drive? My boot drive and one other have a GUID partition table and another has a Master Boot Record. My third external has Tiger installed and has an Apple Partition Map, I am allowed to click the "+" on this drive as well.

Click to expand...

Well, I really don't understand why the one external with GUID doesn't allow for repartitioning (unless it has very little free space left), but the one with Master Boot Record will not allow it as that is a PC partition scheme, and would not allow repartitioning until it were reformatted to Mac OS Extended (Journaled) utilizing an APM or GUID partition scheme.

The GUID external is a puzzler though!

Actually so there is no confusion, I only feel certain that the problem is with the one Master Boot Record partitioned volume. The one GUID that will not allow you to resize the partitions is the kicker.

If by having OSX installed you mean that you believe a full, bootable installation of OSX on the volume is required, that is not correct.

I just checked a couple of external drives I have with GUID partition maps that do not have OSX installed, and they still allow partition additions and resizing as opposed to yours!

Anyhow, didn't want to leave you with impression that they had to have an OSX installation!

JohnNotBeatle said:

Wrong. Leopard Disk Utility allows non-destructive partitioning of HFS+ partitions.

Click to expand...

AWESOME! i stand corrected.

i just tried it on a second internal HD and it started giving me a "grayed out" when the partition was out of room to "split"...

is the partition full?

Vader said:

Sorry if my previous post wasn't clear. I can add partitions to all the GUID and APM (Only reason the one GUID seemed like I couldn't was because it already had 2 partitions and I had to select which partition to add a partition to.) That is what I was trying to say in my last post, sorry I wasn't clear.

I just need to reformat the one drive that has Master Boot Record and everything will work as expected.

Click to expand...

Oh OK! That is cool then as I am sure you will be set then once you get the new partition scheme set up then and I can see that I misread your post about that! You said it right, I just did not read it right! All's well that ends well- and at least there is a reason for the result on the MBR drive!

Edit: Just make sure you change the partition scheme under "Options" in the partition tab of Disk Utility when you do that. Just erasing the MBR drive will not change the partition scheme by itself if I remember right. Erase the drive, then go into the partition tab- but the options button at the bottom will probably still be grayed out. Just change the number of partitions at the top to any number other than one, then put it back to one immediately and the options key will turn black so you can select it and change the type. Best to use GUID if you have an Intel based Mac and APM for a PowerPC based Mac so it could be bootable if you desire down the road (for a cloned boot drive, etc.)!

Great to hear- thanks for letting us know that it worked so other people searching in the future can know that!