Introduction

The availability of a system or component is the amount of time it works normally. For example, a system that works normally for 12 hours a day is 50% available.

Critical systems often need to be highly available, with as little as a few minutes per year of downtime. If your system is required to be 99.999% available, you may need to implement one or more high availability solutions to increase the availability of your system.

There are three main areas where you can implement high availability:

Middle-tier
Infrastructure
Applications