With the preliminary setup out of the way, the Snow Leopard installer will start the actual file copying. It will present a status window that displays an estimated time to complete, and a progress bar that provides a visual clue to how much work is yet to be done.
Copy and Restart
Once the Snow Leopard installer copies the core files to your hard drive, your Mac will restart. Don’t worry if you stay at the gray boot screen for a long period; this process can take a little time.
I waited for what seemed like at least three minutes, although I didn’t actually measure it. Eventually you will return to the installer screen and the status bar will reappear.
The installer will continue to copy necessary files, as well as configure the OS, getting it ready for your use. Once this process is complete, the Snow Leopard installer will display a new window announcing that the installation of Snow Leopard was completed successfully. You can click the ‘Restart’ button and start using your new OS. If you went off to take a coffee break while Snow Leopard was doing all the work for you, your Mac will restart on its own after a minute.
