I have an external 1.5 TB hard drive split evenly with a partition for backup and a partition that was used for Time Machine on my previous computer (OS X Lion).

Now I'm using this hard drive with a new computer (OS X Lion), and I don't want the Time Machine partition anymore. I should also point out that I've never configured Time Machine on my new computer.

I'm trying to remove the Time Machine partition, but the minus (-) option isn't available. Does anyone know why or how I could get the (+/-) options un-grayed?

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  • Disk Utility isn't able or willing to resize partitions so using that tool, you can rename or erase the existing partitions, but not change them. You'll need a tool that works with FAT better to accomplish this.
    – bmike
    Aug 26, 2011 at 16:30
  • Are you sure? According to several sites I've read, since 10.5 you've been able to do just that. macs.about.com/od/applications/ss/diskutilitysize.htm Aug 26, 2011 at 16:45
  • 2
    I suspect the key is in the message "You can't resize the partitions on this disk because it uses the Master Boot Record partition scheme". I have a feeling you can only edit partitions on GUID disks.
    – calum_b
    Aug 26, 2011 at 16:49
  • 1
    Thanks scottishwildcat, I should actually read the entire window before submitting the questions :) Aug 26, 2011 at 17:00
  • 2
    Well, if nothing else, it's a classic example of why too much text in a GUI is a bad thing :)
    – calum_b
    Aug 26, 2011 at 17:10

1 Answer 1


Disk Utility isn't willing/able to resize partitions on MBR disks.

It a way, it's telling you now (poorly) that you can only rename or erase the partitions. It's happy to create this scheme, just won't touch it keeping any data intact.

You will need another tool to make changes to that particular flavor of partition scheme unless you are willing to let Disk Utility repartition and erase all the data.

I don't see a recent article (or have a drive to test on hand), but it sure was a limitation on Leopard.

Mac OS X 10.5: About resizing disk partitions

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