One of the initial criticisms leveled against Mac OS X 10.7 Lion was that, because it’s currently available only from the Mac App Store (a $69 USB drive version is slated to become available this month), it’s not obvious how to recover from problems if your boot hard disk or solid-state drive is damaged. In most situations, where your boot drive is sufficiently functional, you can still perform various recovery actions thanks to a special hidden partition called Recovery HD. In case of trouble, either hold down Command-R at startup, or hold down the Option key at boot to select and start up from that partition. The Recovery HD partition may be read-only and small — only about 650 MB — but its tools can be extremely helpful (thanks to Joe Kissell’s “Take Control of Upgrading to Lion” for these details).
Once your Mac has booted into Recovery mode, you have seven possible actions, the first four of which appear in a Mac OS X Utilities window, and the remaining three of which are available from the Utilities menu:
Restore from a Time Machine Backup. As you would expect, this option enables you to restore from a Time Machine backup on another mounted disk.
Reinstall Mac OS X. How could you reinstall Mac OS X — which is a 3.76 GB download — from a disk that’s only 650 MB in size? Simple — this option downloads the Lion installer from the Mac App Store again. Make sure you have a fast Internet connection.
Get Help Online. Sometimes you just need to look something up, and this option launches Safari to display some local help files. If you have an Internet connection, you can search the Web in general as well.
Disk Utility. This option runs Disk Utility, so you can repair the disk having problems.
Firmware Password Utility. Use this utility to set, change, or remove a firmware password from your Mac.
Network Utility. With Network Utility, you can troubleshoot network connections.
Terminal. Sometimes it’s comforting (or at least useful) to have access to the full Unix command line.
(For a lot more interesting information about Lion Recovery, see Apple’s technical article “About Lion Recovery.”)
But back to my original point — what do you do if your boot drive is sufficiently damaged or otherwise dysfunctional that you can’t boot into Recovery mode? Apple has now released the Lion Recovery Disk Assistant, a standalone app that you can use to make an external Lion Recovery drive using the contents of your existing Recovery HD partition. You must do this on a Mac running Lion, and if your Mac came with Lion pre-installed, the external Lion Recovery drive will boot only that model of Mac; if you upgraded from 10.6 Snow Leopard, the external Lion Recovery drive will boot any Mac upgraded from Snow Leopard. Luckily, because the Recovery HD partition is so small, you can use any external drive that’s at least 1 GB in size, a perfect use for some old USB thumb drive you may have lying around. Just make sure it doesn’t contain any useful data, since it will be erased in the process.
To make your external Lion Recovery drive, follow these steps:
Download the Lion Recovery Disk Assistant (1.07 MB) from the Apple Support Downloads site (it doesn’t appear in Software Update and I somewhat doubt it ever will).
Connect the external drive and launch the Lion Recovery Disk Assistant.
Select the drive and click Continue to start the process of copying the data from the Recovery HD partition. This will take a few minutes.
When finished, the installer tells you how to use the external Lion Recovery drive (hold down the Option key at boot to select the drive). Note that you won’t be able to see anything on this drive; the partition doesn’t even appear in Disk Utility.
The process was simple and easily accomplished, and when I tested my external Lion Recovery drive, it worked perfectly. Although I don’t expect most Mac users to understand the utility of such a tool, I strongly encourage all TidBITS readers running Lion to create one of these external Lion Recovery drives for Macs upgraded from Snow Leopard. And, if you get a new Mac with Lion pre-installed, create another one for that Mac. The simple fact is that you can never anticipate what will go wrong, and if Murphy has anything to say about it, the first time something goes wrong it will be sufficiently bad to prevent you from using your boot drive’s Recovery HD partition.
One final note. A different way to obtain a bootable Lion recovery volume is to clone the disk image hidden inside the Lion installer onto a DVD, thumb drive, or other volume (as Joe discusses in “Take Control of Upgrading to Lion”). Doing so is a bit trickier than using the Lion Recovery Disk Assistant and requires more space (4 GB or more). But you end up with a bootable volume that has all the capabilities of the Lion Recovery drive, plus a complete copy of the Lion installer — meaning you won’t need to download it again if you ever need to reinstall Lion.