Difference between Reliability and Availability
Feature |
Reliability |
Availability |
---|---|---|
Definition |
It is the ability of a system to deliver services correctly under given conditions for a given period of time. |
It is the probability that a system, at a given point in time, would remain operational under normal circumstances. |
Measurement |
Reliability can be measured using metrics such as Mean Time Between Failures (MTBF) or Mean Time to Repair(MTTR). |
Availability is usually measured as a percentage and is calculated as the ratio of the system’s uptime to the total time (uptime + downtime) within a given time frame. |
Focus |
It refers to a failure-free operation during an interval. |
It refers to failure-free operation under normal circumstances at a specific instant of time. |
Time Frame |
It is a long-term measure that looks at the overall performance of a system over its operational lifespan |
It is a short-term measure that assesses the system’s current state and its ability to be available and operational at any given moment. |
Reliability in System Design
The reliability of a device is considered high if it has repeatedly performed its function with success and low if it has tended to fail in repeated trials. The reliability of a system is defined as the probability of performing the intended function over a given period under specified operating conditions.
Important Topics for the Reliability in System Design
- How to achieve high reliability?
- Difference between Reliability and Availability:
- How to measure Reliability?
- What is a Single Point of Failure(SPOF)?
- How to avoid Single point of Failures?