© 2005 by prentice hall chapter 5 maintaining information systems modern systems analysis and...
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© 2005 by Prentice Hall© 2005 by Prentice Hall
Chapter 5 Maintaining Information
Systems
Modern Systems Analysisand Design
Fourth Edition
Jeffrey A. Hoffer Joey F. George
Joseph S. Valacich
© 2005 by Prentice Hall© 2005 by Prentice Hall15-2
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.
© 2005 by Prentice Hall© 2005 by Prentice Hall15-3
© 2005 by Prentice Hall© 2005 by Prentice Hall15-4
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.
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