In the last post, I use the excellent SuperDuper! tool to make a
bootable clone of my hard drive. There are some (more advanced)
techniques that can be used that allow bootable clones to be created
on the command line using free tools. I had some trouble getting
clones to work on the command line, but finally worked through the
problems using the technique described below. Most all of this
information is in Bombich Software’s guide.
- Use Disk Utility to set the drive to use a GUID partition table
Macs can boot without this being the case, but since the internal disk
uses this kind of a partition table, it’s good to have your clone use
the same setup. I’m pretty sure this isn’t necessary, but it worked for
me as I was trying to solve some issues with the clones working.
- Ensure the volume’s “Ignore Ownership on this volume” is *not* checked
By default, external drives will set this option when OS X formats
them. This will ruin the clone, as the system will not boot if files
are set to a UID of 99. So, immediately after formatting your drive,
right click on it and open the “Get Info” option. At the bottom of
that panel, *uncheck* the option that says “Ignore Ownership on this
volume”. This will allow the copy you are going to make to boot.
- Clone with a command like asr, ditto, rsync, etc.
I used ditto successfully:
sudo ditto -X / /Volumes/Clone
For incremental backups, rsync can be used as is described on Bombich Software’s guide to backups:
sudo rsync -xrlptgoEv –progress –delete / /Volumes/Clone
- When booting, get diagnostic information with Command-V
During the first boot from the clone, you can hold down Command-V as
the system boots to get more information about the boot process. If
something goes wrong, at least you’ll have some error messages you can
use as a basis for a search on the internet.