Toy Story 2
So now you're doing your backups — but are you testing them to be sure they are working?
Here's what The Tao of Backup says:
If you really believe that your backups are sound, would you be comforable erasing everything on your hard drive right now, and restoring it from backups?It goes on to list all the many things that can cause backups to not work as you expected.
If not, why not?
No matter how sophisticated or comprehensive your backup system is, you will never know if it works unless you actually test it. Without testing, you can have no confidence at all.
Here are some stories of backups that didn't work. The most dramatic story is that of how Pixar almost lost the files for Toy Story 2 because of backups that weren't working:
In 1998, the most common way to back up a bunch of data was on tape, which is the system that Pixar was using. Unfortunately, these backups were not continuously tested, as the company does today and is the universally recommended best practice. ...I know individuals who've had problems with their backups, too. One person set up online backups with Carbonite — only to find, when she needed to restore files, that the backups had stopped working a couple months prior. Another person was able to restore her files, but found out they all had the same "create" date — the current date — instead of the original date.
This is where the trouble started, because the backups were stored on a tape drive and as the files hit 4 gigabytes in size, the maximum size of the file was met. ... This meant that new data was being written to the drive, but it was ‘pushing’ the older files off. But no-one at Pixar knew this yet.
It's easy to think of these automated backups as a "set it up and forget it" scenario — but things can go wrong with any backup plan.
So let's listen to Brian Teeman:
Repeat after me:
I will make regular backups of my own data.
I will test my backups to make sure they are actually useful.
Credits: Thanks to Kevin Henney, who builds websites, for pointing me to that Toy Story account.