Apple has released a trio of articles that offer new or updated information regarding disk repairs. Let's take a look at each.
Gray progress bar at startup and Snow Leopard
According to an Apple support article, Snow Leopard (Mac OS X 10.6) includes a new repair feature: the Mac may automatically attempt to diagnose and repair disk problems at startup. If this happens, you'll see a gray progress bar on the screen at the same point where the Apple logo appears. While this progress bar resembles the ones that appear during a Safe Boot (a topic I covered here last week) or an EFI firmware installation, Apple confirms that "this issue is not related to firmware."
If the progress bar continues to appear at every startup, it means there is a problem with your drive that the startup repair attempt (presumably the UNIX fsck function) is not able to fix. At this point, you can try alternative solutions--such as running Disk Utility's First Aid (which I doubt will help, as it does pretty much the same thing as fsck, but Apple says to try it) or other repair utilities (such as DiskWarrior or Drive Genius). As Apple warns, if nothing is able to fix the problem, you may ultimately need to erase your drive and restore your data from a backup.
Disk Utility's Repair Disk Permissions and Snow Leopard
Apple has updated its support article on Disk Utility's Repair Disk Permissions with information about changes in Snow Leopard. Most notably, Disk Utility in Mac OS X 10.6 "can only verify/repair permissions of other Mac OS X 10.6 disks. If you need to verify/repair a Mac OS X 10.5 or earlier Mac OS X version, you will need to use a Leopard or earlier disk."
More mysteriously, the article states: "In Mac OS X 10.5 or earlier, when you verify or repair disk permissions Disk Utility reviews each of the .bom files in /Library/Receipts/ and compares its list to the actual permissions on each file listed." The mystery is that the article does not describe what, if anything, Mac OS X 10.6 does differently.
Repair Disk Permissions messages that you can safely ignore
An updated Apple support article expands the list of error messages that you can "safely ignore" if they appear after running Repair Disk Permissions in Disk Utility. Even though over 100 messages are listed, it is not a complete list. Apple admits that these are only "examples" of such errors; others include almost any "ACL found but not expected..." message.
This has been a long-standing issue with Disk Utility (as I have noted here before). Frankly, I don't understand why Apple does not offer a better solution. The typical Mac user is probably unaware of these "safe" errors and likely to remain concerned after seeing them--especially as they often do not get fixed after selecting to Repair. Why can't Apple modify Disk Utility so that it either does not display these errors or identifies them as "safe"? Perhaps a fix here couldn't cover every possible ignorable error, but it could certainly cover most of them.
This story, "Bugs & Fixes: Apple Updates Disk Repair Advice" was originally published by Macworld.