Availability

Availability, abbreviated as A, is the degree to which a system, service, or resource is accessible and operational when needed by users or clients.  It is a measure of reliability that indicates the percentage of time a system is functioning properly and able to perform its intended tasks without interruption.  It takes into account all events that stop planned production like breaks, lunches, or pre-arranged time.

In computing and technology contexts, availability is often expressed as a percentage and is calculated based on the total time the system is expected to be available versus the total time it is actually available.

High availability is a crucial requirement for many systems and services, especially in critical sectors like finance, healthcare, telecommunications, and e-commerce, where downtime can lead to significant financial losses, reputational damage, or even risks to public safety.  Organizations invest in redundancy, failover mechanisms, backup systems, and other measures to maximize the availability of their infrastructure and services.

 

ailability Formula

\( A =  RT \;/\; PPT  \)

Symbol

\( A \) = availability

\( RT \) = run time

\( PPT \) = planned production time