I've been long overdue for some sysadmin house cleaning - cleaning up my backup drives, and organizing the hundreds of Gigs of data that I've managed to convince myself are important.

Finally today I managed to remove many of the obsolete and duplicate items on my 400GB LaCie external firewire drive, assisted by Grand Perspective, a little software utility for MacOS X that visualizes files via a tree map. This gives a nice graphical overview in which every single file is represented by a rectangle, color coded by folder (for example). The size of the rectangle is proportional to the size of the file on disk. This makes it relatively easy to spot duplicate files and folders.

Within a couple of hours I was able to remove approximately 180GB of files that were duplicates or no longer of interest.