Automation - The Practice of Cloud System Administration - page 242

12.1.1 The Left-Over Principle
Using the left-over principle, we automate everything that can beautomated within reason.
What'sleftishandledbypeople:situationsthataretoorareortoocomplicatedtoautomate.
This view makes the unrealistic assumption that people are are infinitely versatile and ad-
aptable, and have no capability limitations.
The left-over principle starts by looking at the tasks that people do, and uses a number
of factors to determine what to automate. In the area of system administration, there are
many things that operations staff do. All of them can be classified along the axes shown in
Figure 12.1 .
Figure 12.1: Tasks can be classified by effort and frequency, which determines the next
step in how to optimize them.
The x -axis is labeled from “rare” to “frequent,” representing how often a task is done.
The y -axis is labeled from “easy” to “difficult,” representing how much effort the task re-
quires each time it is performed.
• Tasks classified as rare/easy can remain manual. If they are easy, anyone should be
able to do them successfully. A team's culture will influence if the person does the
right thing.