OS X Mountain Lion: The Missing Manual

The Setup Assistant

What you see depends on whether you installed Mountain Lion onto an older OS X drive or an empty drive.

After Installing Over Snow Leopard or Lion

If you installed onto a drive that already had OS X stuff on it—accounts, files, settings, and so on—then after the Mac restarts, all you have to do is log in as usual. Enjoy the box that warns you about Lion’s upside-down scrolling habit (Full-Screen Mode, Safari). Click Start Using Mountain Lion, and start using Mountain Lion.

TROUBLESHOOTING MOMENT: Journaling

If you decide to erase your hard drive before installing Mountain Lion, you’re offered a choice of several formats for your hard drive. But you should stick with the factory setting, “Mac OS Extended (Journaled).” It turns on a special background feature of OS X known as file journaling.

When file journaling is turned on, your Mac keeps a personal diary of everything you do on your hard drive—opening, saving, deleting files, and so on. Journaling offers two benefits: a shorter startup time and safety in the event of a crash.

Here’s how it works: When you press the power button, OS X checks to see whether your computer was shut down properly (by choosing →Shut Down, for example, instead of just pulling out the plug).

If you didn’t shut down properly, OS X examines your hard drive the next time you start up to see if it needs repair. It has to scan the whole drive–which ...