Reliability in software is software that has no failure and works in a special time period with a special environment. Hardware reliability is the probability of the absence of any hardware-related system malfunction for a given mission on the other hand software reliability is the probability that the software will provide a failure-free operation in a fixed environment for a fixed interval of time. The article focuses on discussing the difference between Hardware Reliability and Software Reliability.
Hardware Reliability
Hardware reliability is the probability that the ability of the hardware to perform its function for some period of time. It may change during certain periods such as initial burn-in or the end of useful life.
- It is expressed as Mean Time Between Failures (MBTF).
- Hardware faults are mostly physical faults.
- Thorough testing of all components cuts down on the number of faults.
- Hardware failures are mostly due to wear and tear.
- It follows the Bathtub curve principle for testing failure.
Software Reliability
Software reliability is the probability that the software will operate failure-free for a specific period of time in a specific environment. It is measured per some unit of time.
- Software Reliability starts with many faults in the system when first created.
- After testing and debugging enter a useful life cycle.
- Useful life includes upgrades made to the system which bring about new faults.
- The system needs to then be tested to reduce faults.
- Software reliability cannot be predicted from any physical basis, since it depends completely on the human factors in design.
Hardware Reliability vs Software Reliability
| Features | Hardware Reliability | Software Reliability |
|---|---|---|
| Source of Failure | Failures are caused due to defects in design, production, and maintenance. | Failures are caused due to defects in design. |
| Wear and Tear | Failure occurs due to physical deterioration in wear and tear. | In software reliability, there is no wear and tear. |
| Deterioration Warning | In this prior deterioration warning about failure. | In this no prior deterioration warning about failure. |
| Failure Curve | The bathtub curve is used for failure rates apply. | There is no Bathtub curve for failure rates. |
| Is Failure Time-dependent? | In this failures are time-dependent. | In this failures are not time-dependent. |
| Reliability Prediction | In this reliability can be predicted from design. | In this reliability can not be predicted from design. |
| Reliability Complexity | The complexity of hardware reliability is very high. | The complexity of software reliability is low. |
| External Environment Impact | Hardware reliability is related to environmental conditions. | External environment conditions do not affect software reliability. |
| Reliability Improvement | Reliability can’t be improved through redundant of hardware. | Reliability can be improved through redundancy of software. |
| Maintenance | Repairs can be made that make hardware more reliable through maintenance. | No equivalent preventive maintenance for software. |