Does anyone know how to change the UUID of a Volume? The background for this question is that I have a duplicate UUID issue:

I have /Volumes/OldMacHD with a UUID of XYZ. I have /Volumes/Mirror1 with a UUID of XYZ (same UUID! I bet that's because OldMacHD USED to be part of this mirror). I got these UUIDs via 'diskutil info /dev/thatdisknumber | grep UUID'.

I'd like to change the UUID of 'Mirror1'.

I discovered by chance the 'hfs.util' utility, since these are HFS volumes after all. The man page for hfs.util says that if you issue the -s flag, this changes the UUID. However, if you type hfs.util all by itself, it doesn't show you the -s option at all, just every option besides that! Grr. I tried it anyway:

sudo /System/Library/Filesystems/hfs.fs/hfs.util -s /dev/disk4 (the raid volume).  

Nothing happens. No error message, no success message. UUID exactly the same. I tried it while the volume was unmounted.

Any ideas?