In the following IT Dojo video, I show you how to use Target Disk Mode (TDM) to access the hard drive of a Mac that won't boot.
Original blog post:
In the blog post, I point out that TDM can be a security risk. Accessing a drive through TDM bypasses most security for local accounts and even network accounts. I could find only two exceptions. First, if you configure an Open Firmware Password, the machine will not enter TDM. Second, if you encrypt your home folder using FileVault, you won't be able to access the data without the FileVault password. You'll also have to find the hidden FileVault image using the "Go to Folder" menu option or terminal.
Despite TDM's security risks, I think it's an extremely handy feature that I would like to see Windows offer. Besides, I subscribe to the general assumption that if someone has physical access to the machine they can probably access the data on that machine. What do you think?