97 Things Every Cloud Engineer Should Know

Chapter 6. A Cloud Computing Vocabulary

Jonathan Buck

Senior Software Engineer at Amazon Web Services

In any profession, being able to speak and understand the vernacular goes a long way toward feeling comfortable in your role and working effectively with your colleagues. If you’re just starting your career as a cloud engineer, you will likely hear these terms throughout your workplace:

Availability

The amount of time  that a service is “live” and functional. This is often expressed in percentage terms. For example, if someone says their service has a yearly availability of 99.99%, that means it will be unavailable for only 52.56 minutes in an entire year.

Durability

Even for the most reliable devices, any data stored on a computer is ephemeral over a long enough time frame. Durability refers to the chance that data will be accidentally lost or corrupted over a given time period. Like availability, it’s typically expressed as a percentage value.

Consistency

Consistency refers to the notion that when you write data to a data store, it (or the latest version of it) might not be immediately available. This is because cloud-based data stores are built on distributed systems, and distributed systems are subject to the CAP theorem. (Also known as Brewer’s theorem, it holds that there are three things a distributed data store can guarantee—consistency, availability, and partition tolerance—but ...