For those wondering “Why is there a progress bar when my Mac is starting up?,” there now seems to be an answer. Thanks to an Apple support document entitled “Gray progress bar appears under Apple logo during startup,” as well as some research done by The Unofficial Apple Weblog (TUAW), those plagued by the GOWFTPBTF (gray-screen-of-waiting-for-the-progress-bar-to-fill) now have an explanation as to why their computers are behaving this way.
“A gray progress bar may appear below the Apple logo each time the computer starts up. The bar may remain a few minutes before the Finder or login window appear,” Apple’s support article TS3148 reads. “If this happens each time your Mac starts up, it probably indicates Mac OS X v10.6 is attempting to diagnose and resolve an issue with your hard disk or the data on it.”
As TUAW reveals, there are more possible instances that can trigger this behavior, including shutting down your Mac as it attempts to boot. An explanation provided by Apple itself includes hardware failure. In any situation, it is advised that, once you have experienced this, you should back up all your important data as soon as you get a chance to do so. In fact, as power users will agree, one should always keep backups, in case anything goes wrong. Eventually, something will.
“If this occurs each time you start your Mac, you should back up your important data because hard drive issues can potentially lead to data loss,” Apple says. “You can use Time Machine to back up your system to a different disk, or back up important files to MobileMe, a burnable disc, or a different location if available.”
And, while Apple advises the use of the Mac OS X built-in backup utility, Time Machine, TUAW claims the healthiest way to go may actually be a manual backup – simply archive all your stuff manually and store it on a separate volume. As many users have probably experienced, Time Machine can also create faulty backups, which eventually cannot be used to restore Mac OS X.
Mac OS X Gray Startup Screen (Progress Bar) Explained
Find out what causes Mac OS X to behave this way, and the steps you need to take