OS X, as you’ve probably heard, no longer comes on a DVD. When your Mac won’t even start up, there’s no DVD to insert as a backup startup disk. That’s a scary place to be; if your hard drive is sick, then everything on it may be inaccessible to you. What you need is an emergency drive that can repair the hard drive and get you back in operation.
Apple is way ahead of you on this one. It offers three simulated repair disks: three ways to supply disk-repair and system software–repair tools in times of crisis.
Here’s the sneaky surprise: When you install El Capitan, it automatically creates an invisible hidden “hard drive” (a partition of your main drive that has its own icon) called Recovery HD. It’s a 650-megabyte “drive” that’s generally invisible to you. It’s also invisible to Disk Utility, so even if you erase your hard drive, the Recovery HD is still there to help you.
But if you can’t seem to start up your Mac properly, or if your hard drive is acting a little flaky, you’ll be glad you had this “separate” startup disk. On it, Apple has provided some emergency tools for fixing drive or software glitches, restoring files, browsing the web, and even reinstalling OS X.
Note
The OS X installer creates the Recovery HD partition only if your startup drive is an internal drive. In certain other situations, it won’t create the partition—for example, if you’re installing OS X onto a RAID volume or one with a non-standard Boot Camp partition setup.
You can power up your Mac from the Recovery HD in either of two ways:
Hold down ⌘-R as the Mac is starting up. You can let go when you see the Apple logo appear.
Hold down the Option key as the Mac is starting up. When you see the Startup Manager (Figure B-3, top), let go. Click the up-arrow button below the Recovery HD icon.
Either way, you wind up at the Utilities screen shown in Figure B-3, bottom.
Figure B-3. Top: This simple display of disk icons is known as the Startup Manager. It’s an easy way to specify which disk you want to start up from. Bottom: Here’s the point of the Recovery HD partition: a screen full of emergency utilities that can fix your Mac’s regularly scheduled hard drive. If there’s a pop-up menu at the bottom, it’s for choosing a Wi-Fi hotspot so that you can access the rest of your network. That might be useful when, for example, you want to access your Time Machine backups.
Here Apple has supplied you with four important tools:
Restore From Time Machine Backup. If your Mac is really hosed, this is the option you want. It restores your entire software world—programs, data, settings, OS X itself—from the Time Machine backup you carefully set up as you read Chapter 6.
This option completely erases your existing hard drive, so—you know. Be sure.
Once you choose this option, click Continue. You’re now asked to choose the Time Machine drive, then the time-stamped backup you want to restore from, and, finally, the drive or partition you want to wipe out. You get one more warning that you’re about to wipe out the destination drive. When you click Continue, the restoration begins. When it’s all over—usually a couple of hours later—the Mac restarts as though nothing ever happened.
Reinstall OS X. You can use this option to install a copy of OS X onto any hard drive—for example, you could reinstall it on your main internal drive.
Get Help Online. This option opens your Safari web browser, which presents you with some helpful information about using the Recovery Mode that you’ve fired up. You’re actually online at this point, so you can also visit any other website you might find helpful.
Quit Safari when you’re finished browsing; you return to the main OS X Utilities window.
Disk Utility. Use this option to open Disk Utility, the Mac’s hard drive diagnostics-and-repair program. You can use it to check, fix, erase, or partition any of your hard drives.
For example, you can repair the main startup disk, which is often the most useful option.
Those four options are the big-ticket items, but don’t miss the menu bar. The commands here let you open the Firmware Password Utility (Setting Up the Login Process), Network Utility (Migration Assistant), and Terminal (Saving a report).
OK, the Recovery HD concept is clever. And most of the time, it’s all you need.
But what if your hard drive is completely hosed? What then, smart guy? You can’t very well boot up from the Recovery HD if it’s sitting on the same dead hard drive.
Or what if you’ve just installed a brand-new, bigger, or faster hard drive? It doesn’t have OS X on it. It doesn’t have Recovery HD on it. How are you supposed to install El Capitan?
In those situations, recent Mac models—those released in 2011 and later—offer an even cleverer option: Internet Recovery. This mode offers the same exact options that the Utilities screen of Recovery HD would have—but you’re connecting to that software online, over a high-speed Internet connection. You’re literally starting up from Apple’s hard drives, thousands of miles away.
So even if your hard drive is dead as a doornail, you can still repair it, reinstall OS X, and so on.
To fire up Internet Recovery, make sure your computer is in a Wi-Fi hotspot or connected to an Ethernet network. Then hold down ⌘-R as the computer is starting up. You can let go when you see the screen that asks you to choose a Wi-Fi network. Do that, and then enter the password for the network, if necessary.
Now your Mac downloads a disk image containing just enough software to get you to the Utilities screen described in the previous section.
But what if the hard drive is so sick that you can’t start up from the Recovery HD—and your Mac isn’t new enough to offer the Internet Recovery feature? (Or what if it does offer that feature, but you’d rather repair your Mac a quicker way?)
The solution is to build yourself a bootable OS X flash drive or hard drive, as described on Gray Screen During Startup. Not only is it capable of starting up or reinstalling OS X, but it also has a complete set of recovery tools on board.
To use this emergency disk, hold down the Option key as the Mac starts up. You wind up at the Startup Manager screen shown in Figure B-3, top. From the pop-up menu, choose your Wi-Fi hotspot.
Now click the up-arrow button below the Recovery HD icon. (You may even see two Recovery HD icons—one of them is the USB flash drive, and the other is the invisible partition on your hard drive. Either one works.) Your Mac is starting up from the flash drive! After a moment, you wind up at the Utilities screen described earlier in this appendix.