== Another aphorism of system administration

> If you haven't tested it, it doesn't work.

I got this from the Extreme Programming movement, but it's just as
applicable to systems and procedures as it is to developing software.
(Remember [[verifying backups|CheckYourBackups]]? That's an instance
of this aphorism.)

This has an important corollary:

> If you aren't checking it, it's broken.

For example, when you have a spiffy hardware RAID system you should
make very sure that you do indeed get notified when a disk goes bad
and your RAID ceases to be redundant. Otherwise, you will sooner or
later appear in a
[[comp.risks digest|http://catless.ncl.ac.uk/Risks]] story.