When hard-drive disaster strikes, you need to start up your Mac from another drive to repair it. In days gone by, you would typically boot from the install CD or DVD that came with your Mac (assuming you could recall where you stashed it) and run Apple's Disk Utility from there. But today's Macs no longer ship with any optical disc--heck, most Macs ship without any optical drive. So what do you do instead? Your best bet is to prepare ahead.Related StoriesIs Apple's move from Samsung to Sandisk in Retina MacBook causing fan spin issues?How to think like a Mac geek
