Several people have recommended using "time machine" for backing up.
I have a terrabyte for TM and it fills quickly.
I can backup my video files easily enough, but just what should I backup of FCPX so that a crash can be recovered from?
And where is all the relevant data located?
Cheers
Wayne

The trick is to move the Events files to another drive not included in the Time Machine queue and just back up the Project files to Time Machine. The Project files contain all the editing info and this is what you need in case of a catastrophic FCPX crash. The Event files contain all the video, audio and graphic files you are using in a project and can get big. Moving files is built into FCPX and works quite well. As a precaution you should back up the drive with the Events files manually to another drive.

Thanks William

I like to use Carbon Copy Cloner to make disk images. It makes restoring the backup as easy as formatting the target drive & using CCC to clone the backup back onto it.