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Reliability

Reliability. and. Integrity. Made by: Sambit Pulak XI-IB. Definition:.

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Reliability

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  1. Reliability and Integrity Made by: Sambit Pulak XI-IB

  2. Definition: 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 Data may be unreliable if it has been entered incorrectly or if it becomes outdated.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.

  3. Hardware Reliability Hardware Reliability is the ability of hardware to perform its functions for some period of time.

  4. Software Reliability  Software Reliability is defined as: the probability of failure-free software operation for a specified period of time in a specified environment. Although Software Reliability is defined as a probabilistic function, and comes with the notion of time, we must note that, different from traditional Hardware Reliability, Software Reliability is not a direct function of time. Electronic and mechanical parts may become "old" and wear out with time and usage, but software will not rust or wear-out during its life cycle. Software will not change over time unless intentionally changed or upgraded. Software Reliability is hard to achieve, because the complexity of software tends to be high. While any system with a high degree of complexity, including software, will be hard to reach a certain level of reliability.

  5. Data Integrity In short, Data Integrity refers to the validity of data. Data integrity can be compromised in a number of ways: • 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 There are many ways to minimize these threats to data integrity. These include: • 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

  6. Types of integrity constraints Data integrity is normally enforced in a database system by a series of integrity constraints or rules. Three types of integrity constraints are an inherent part of the relational data model: entity integrity, referential integrity and domain integrity. Entity integrity concerns the concept of a primary key. Entity integrity is an integrity rule which states that every table must have a primary key and that the column or columns chosen to be the primary key should be unique and not null. Referential integrity concerns the concept of a foreign key. The referential integrity rule states that any foreign key value can only be in one of two states. The usual state of affairs is that the foreign key value refers to a primary key value of some table in the database. Occasionally, and this will depend on the rules of the business, a foreign key value can be null. In this case we are explicitly saying that either there is no relationship between the objects represented in the database or that this relationship is unknown. Domain integrity specifies that all columns in relational database must be declared upon a defined domain. The primary unit of data in the relational data model is the data item. Such data items are said to be non-decomposable or atomic. A domain is a set of values of the same type. Domains are therefore pools of values from which actual values appearing in the columns of a table are drawn.

  7. Poor data reliability and integrity can have enormous social, political and economic impacts.

  8. Bibliography http://itgsopedia.wikispaces.com/Strand+1+Index http://www.ruthtrumpold.id.au/itgswiki/pmwiki.php?n=Main.Reliability http://www.ruthtrumpold.id.au/itgswiki/pmwiki.php?n=Main.Integrity http://www.webopedia.com/TERM/D/data_integrity.html https://docs.google.com/document/d/1i4FInCZKgK4OFZJrO6CJPv_luyNU3CcRLt18vD_qEXg/edit?pli=1 http://www.ece.cmu.edu/~koopman/des_s99/sw_reliability/

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