Reliability

Okay, so let's say you've got 5 9's of availability. That's 99.999% uptime. Pretty solid. But what about reliability?

Reliability is about how well your system works when it's up. For example, maybe your server is responding to HTTP requests, but it's returning erroneous data because some dependency is down. That's not reliable.

The reliability of S3 is very high out of the box.