10.7: Create your own Recovery HD
Jul 25, '11 07:30:00AM
Contributed by: cycomachead
This hint shows how to create your own Recovery HD (Disc or Flash Drive).
Mac OS X Lion includes a hidden Recovery HD. This is a small partition about 650MB in size which you can boot from by pressing down Option at startup. It includes a variety of utilities which can help you troubleshoot a Mac.
It can be very handy to have a bootable copy of your own on some other media incase you need to troubleshoot a Mac with a bad drive, or something has happened to the recovery partition, unlikely but possible.
To do this we need to find and mount the hidden disk image with the Installer.
- Open up Terminal and type
defaults write com.Apple.Finder AppleShowAllFiles true
This is done to be able to see hidden files, including the disk image used to create the recovery disk.
- Restart Finder via your preferred method. (Force Quitting, killall in Terminal, or logging out all work the same.)
- In Finder find where you saved your Mac OS X Lion Installer to (probably your /Applications folder) and right click and select 'Show Contents.'
- Go into the Contents/SharedSupport folder and open InstallESD.dmg
- Now find BaseSystem.dmg and mount (open) it. The file is a 'hidden file' and will be slightly greyed out.
- Now you need at least 1.1GB of free space on a flash drive or DVD. You can use either a 2GB drive, or partition your larger one, but I recommend keeping the Recovery partition free from your normal files that go on a flash drive. Make sure this partition is formatted as Mac OS X Extended Journaled. (You'll probably want to have the rest of your flash drive formatted as FAT if you work in a multi-platform environment.)
- Copy over the entire contents of BaseSystem.dmg to your flash drive however you like. You can use Restore in Disk Utility, the Terminal, or your favorite cloning app. Make sure that you get all the invisible files that are there if you're copying over everything manually. Or if you're burning a disk, make sure you're burning the contents of the disk image, and not just the image itself (it won't be bootable that way).
- Restart the Mac holding down Option, and test the drive to see if it worked. If you named your flash drive Recovery HD then it will have a USB drive icon when it starts up compared to the Recovery HD with a hard drive icon, which is that part that is on your actual startup drive, or you can name it anything you like.
- Now, turn off the invisible file viewing in Finder if you want to. (There's no danger to keeping it on all the time as long as you know which files you can and can't mess with.) To do this go back into Terminal and type:
defaults write com.Apple.Finder AppleShowAllFiles false
- Restart Finder to see the setting take effect.
[crarko adds: I think it's always a good idea to have a different recovery device than a partition on the main boot drive.]
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