Topic: Reliability and Integrity

Reliability refers to the operation of hardware, the design of software, the accuracy of data or the correspondence of data with the real world. Data may be unreliable if it has been entered incorrectly or if it becomes outdated. The reliability of machines, software and data determines our confidence in their value.

Integrity refers to safeguarding the accuracy and completeness of stored data. Data lacks integrity when it has been changed accidentally or tampered with. Examples of data losing integrity are where information is duplicated in a relational database and only one copy is updated or where data entries have been maliciously altered.

Now that technology and computers are so often used in an innumerable amount of places, reliability is becoming a critical aspect of information technology in our society. For example, the software used in airplanes and air traffic control centers must be extremely reliable, considering the fact that many lives are in grave danger in the event of a failure.

Software Reliability is the probability of failure-free software operation for a specified period of time in a specified environment. Software Reliability is also an important factor affecting system reliability. It differs from hardware reliability in that it reflects the design perfection, rather than manufacturing perfection. The high complexity of software is the major contributing factor of Software Reliability problems.

 Failure cause: Software defects are mainly design defects.  Wear-out: Software does not have energy related wear-out phase. Errors can occur without warning.  Repairable system concept: Periodic restarts can help fix software problems.  Time dependency and life cycle: Software reliability is not a function of operational time.  Environmental factors: Do not affect Software reliability, except it might affect program inputs.  Reliability prediction: Software reliability can not be predicted from any physical basis, since it depends completely on human factors in design.  Redundancy: Can not improve Software reliability if identical software components are used.  Interfaces: Software interfaces are purely conceptual other than visual.  Failure rate motivators: Usually not predictable from analyses of separate statements.

 Human errors when data is entered.  Errors that occur when data is transmitted from one computer to another.  Software bugs or viruses Hardware malfunctions, such as disk crashes Natural disasters, such as fires and floods.

 Backing up data regularly.  Controlling access to data via security mechanisms.  Designing user interfaces that prevent the input of invalid data using error detection and correction software when transmitting data.

 ITGS compiled notes  