We frequently harp on not only keeping data backups, but also on ensuring that your backups are good. (That’s why Adam Engst has designated every Friday the 13th as International Verify Your Backups Day.) It’s inconvenient to lose some recent files or email messages, but a good backup policy is even more essential for larger projects — like an entire movie. Two people involved explain how Pixar nearly lost a year’s worth of work on the movie “Toy Story 2” after someone accidentally entered rm * (the Unix command to delete all files) and the company discovered their backup had been compromised. The film’s salvation came from an unexpected source.