Ask Different is a question and answer site for power users of Apple hardware and software. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I currently have a 640GB external HD that has 1 partition formatted as HSF+ Now I want to split some of the free space into a new FAT32 partition, without having to reformat the whole HD and losing all my data. I read that I'm supposed to be able to add new partitions in the Hard Disc Utility by clicking the "+" sign, without any loss of data. But in my case the "+" is not clickable and it says that this partition cannot be altered.

Can anyone tell me how to proceed. Or is it impossible without reformatting the whole disc?

I'm running OS X Snow Leopard 10.6.6

share|improve this question
up vote 0 down vote accepted

So far I know is that if you don't use the MAC OS EXTENDED Format and a GUID Partition table for the first partition you won't be able to adjust the size of the partition or squeeze in a new one. The only thing you can do is create a new partition with the free unpartitioned space on the ext. HD which is left over (supposed you left over some free unpartioned space).

share|improve this answer
Unfortunately I don't have unpartioned space left, and I don't have space to backup my data and reformat the whole disc :'( But thanks for the answer – Bart Mar 11 '11 at 20:48

You should unmount the disk before you try to change the partitions.

That should work.

share|improve this answer
Unmount is the same as right-clicking and ejecting the disc right? Unfortunately that's not working, it still says that this partition cannot be modified – Bart Mar 11 '11 at 17:26

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.