OS X has a couple of ways to bypass the normal starup process from your main boot device.  One extremely useful one (for reasons discussed in a later post) is to start up OS X in “Firewire Target Mode”.  If you hold down the “T” key when powering up, the machine will start up as a Firewire drive.  The screen displays an extremely large version of the Firewire logo on the primary display and you can connect a Firewire cable from the machine to another machine’s Firewire port.  The computer should mount like any other external Firewire device, turning your computer into the world’s most expensive external disk drive.

This can be extremely useful for copying files off a machine to another one, and in my case what made it especially useful is that it is easy to boot up a machine in Firewire mode even if the video is not working.  You can easily hold down the “T” key while booting, even if the screen isn’t visible (more on that in a later post).  Any other transfer off a machine usually requires either physically removing the hard drive, or interacting with the operating system to turn on network sharing of one kind or another.  This is quite impossible when you can’t interact with the video.

This also brings up the importance of encryption of sensitive information, since anyone getting physical control of your machine can boot it up and attach another computer to it.  One encryption approach uses File Vault to encrypt your whole home directory.  This is very good encryption for someone that doesn’t want to think about it.  I personally don’t use it for a few reasons.  One, I don’t feel the need to waste my computer’s time encrypting iTunes songs, temporary internet files, and other trivia in my home directory that I don’t care about and that will lengthen a back up process.  And two, it complicates the ability to pull off files like with this Firewire trick.

Another encryption approach uses Disk Utility to define encrypted file shares of my choosing.  I define a dynamic file share and set encryption for it as needed for some of the categories of documents I store (like “Admin”, or “Financial”) and treat these file shares like top level folders on a drive.  There are multiple encryption choices and only the files I want encrypted are placed in the file shares.  These partitions are mounted or dismounted as needed for my work.

So, with the mounted Firewire computer I was able to drag off and backup the encrypted and unencrypted files from the soon-to-be-shipped-off-for-repair computer.  This made me feel safe about my data, and safe to ship off my computer with the sensitive files locked up.