Diskutil resizeVolume error

Question

I am trying to resize my drive in my macbook pro to accomodate a fat32 swap partition to share inbetween xp and osx. However, I am getting an error. This is what I'm looking at:
zenith:~ jmeyer$ diskutil list
/dev/disk0
#: type name size identifier
0: GUIDpartitionscheme *149.1 GB disk0
1: EFI 200.0 MB disk0s1
2: Apple_HFS Zenith 148.7 GB disk0s2
zenith:~ jmeyer$ sudo diskutil resizeVolume disk0s2 88.5G "HFS+" Media 30G "MS-DOS FAT32" Windows 30G
Password:
Started resizing on disk disk0s2 Zenith
Verifying
Resizing encountered error The underlying task reported failure on exit (-9972) on disk disk0s2 Zenith
zenith:~ jmeyer$
Is there something that's missing or what am I doing incorrectly here?

Answer 1

Hi eeboarder,
   If you search you should be able to find what I did about the error. For instance, Apple's discussion of it can be found at Disk Utility reports "Underlying task reported failure" when repairing a volume. However, it's a non-specific error that doesn't indicate a problem in Disk Utility. I gather that it means that some system call made by Disk Utility failed and there are thus lots of possibilities.
   In most cases you would read about in a search, the disk in question was failing. Thus you should use every tool at your disposal, including verifying the disk with Disk Utility, to test the disk. However, I would guess that the problem here is that you're trying to resize a partition while it is being used as the boot volume. That should definitely fail; you can't erase the boot partition while the system is using it. I would think that the easiest way to do this would be to reformat and install. You can repartition the disk in conjunction with reformatting it.
   Since you tried to resize the boot partition while it was running, I gather that you weren't planning on reformatting and installing. Something may have changed recently but in the past, Apple disk tools have been unable change a partition without reformatting the disk. I assume that is because that's the only way to do it reliably. There are third party HFS disk tools that can resize a partition without losing data but there is certainly risk involved so I would never do that without a good backup.
Gary
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