13 Improving an attribute with another attribute

 

This chapter covers:

  • Checking one attribute can be necessary to control another
  • Recognizing that user needs are sometimes not explicit
  • Checking production software

In movies, it’s rare for sequels to be as good or outshine the first film. There are a few: The Godfather Part II, The Empire Strikes Back, The Dark Knight, and Aliens, among others. Near the end of the 1990s, the wizards of Pixar worked on the sequel to their 1995 film Toy Story (to be released in 1999) — which many think is better than the first movie, but also a sequel that almost didn’t happen.

One of the animators working on Toy Story 2 typed in a command to remove all files and directories — at the wrong location — and accidentally deleted about two years of data that all of the animators used to create the film (models for different parts of characters and other things). It was a disaster and Pixar had to recover the data from backups.

At the time, the whole movie encompassed around 10GB but when the system administrators at Pixar went to restore the data, they found out that the tapes they backed it up to could only hold 4GB of data. The error logs that could have told them that were stored on the same tape drive and because the drive was full the error log was empty. When the 10GB worth of data was being backed up to a 4GB tape, it started pushing out data it had previously written by overwriting it. The film was lost.

13.1  TL;DR

13.2  Recoverability

13.3  Integrity

13.3.1  Checksums

13.3.2  Test checksums with a data generating program

13.4  Backing up our files

13.5  Monitoring recoverability

13.5.1  One usability attribute can be required for another

13.5.2  Create the quality control plugin

13.5.3  Try out the quality control

13.6  Summary