Disk Utility: choose disk or volume? When using disk utility to verify/repair permissions (or verify/repair the disk itself), I've never been clear whether I should perform operations on the disk ("WDC WD1200BEVE-00WZT0" in my case) or on the volume nested beneath it ("MacintoshHD"), or both. I usually do both, but is this necessary?
It can't hurt to repair permissions on your actual disk, but it is quite unnecessary, because "Macintosh HD" contains the actual operating system, so the stuff that you want to repair.