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Chapter 5 Maintaining Information

Systems

Modern Systems Analysisand Design

Fourth Edition

Jeffrey A. Hoffer Joey F. George

Joseph S. Valacich

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Learning ObjectivesExplain and contrast four types of

system maintenance.Describe factors affecting maintenance

costs.Describe maintenance management

issues, including organizational structure, quality measurement, change management, and configuration management.

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The Process of Maintaining Information Systems

Process of returning to the beginning of the SDLC and repeating development steps focusing on system change until the change is implementedMaintenance is the longest phase in the SDLCFour major activities: Obtaining maintenance requests Transforming requests into changes Designing changes Implementing changes

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Maintenance is like a mini-SDLC

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Types of System MaintenanceCorrective maintenance

Changes made to a system to repair flaws in its design, coding, or implementation

Adaptive maintenance Changes made to a system to evolve its functionality

to changing business needs or technologies

Perfective maintenance Changes made to a system to add new features or to

improve performance

Preventive maintenance Changes made to a system to avoid possible future

problems

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By far, most maintenance is corrective, and therefore urgent and non-value adding.

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The Cost of Maintenance

Many organizations allocate eighty percent of information systems budget to maintenanceFactors that influence system maintainability:

Latent defects Number of customers for a given system Quality of system documentation Maintenance personnel Tools Well-structured programs

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A well-documented system is easier to understand, and therefore easier to maintain.

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Conducting System MaintenanceManaging Maintenance

Number of people working in maintenance has surpassed number working in development.Three possible organizational structures: Separate

Maintenance group consists of different personnel than development group.

Combined Developers also maintain systems.

Functional Maintenance personnel work within the functional

business unit.

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Advantages and DisadvantagesMaintenance Organization Type

Advantages Disadvantages

Separate Improved system and documentation quality

Ignorance of critical undocumented information

Combined Maintenance group knows all about system

Less emphasis on good documentation

Functional Personnel have vested interest

Limited job mobility and human or technical resources

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Conducting System MaintenanceMeasures of Effectiveness

Important factors to consider Number of failures Time between each failure Type of failure

Mean time between failures (MTBF) A measurement of error occurrences that

can be tracked over time to indicate the quality of a system

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Expect lots of failures early, but as corrective maintenance takes place, error rate should decrease rapidly

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Maintenance requests can be frequent

Prioritize based on type and urgency of request

Controlling Maintenance Requests

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Evaluations are based on feasibility analysis

The Flow of a Maintenance Request

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Configuration ManagementThe process of assuring that only authorized changes are made to the systemBaseline modules

Software modules that have been tested, documented, and approved to be included in the most recently created version of a system

System librarian A person responsible for controlling the checking out and

checking in of baseline modules when a system is being developed or maintained

Build routines Guidelines that list the instructions to construct an

executable system from the baseline source code

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Configuration Management ToolsSpecial software systems for managing system configurationControls access to modules in the system libraryTwo types Revision control: modules labeled as frozen

(unchangeable) or floating (checked out by programmer for modification)

Source code control: extend revision control to all interrelated modules

Historical changes can be traced and previous versions can be reconstructed

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SummaryIn this chapter you learned how to: Explain and contrast four types of system

maintenance. Describe factors affecting maintenance

costs. Describe maintenance management issues,

including organizational structure, quality measurement, change management, and configuration management.