Keeping Software Alive: The Maintenance Phase, Explained

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Keeping Software Alive: The Maintenance Phase

System Analysis and Design · Chapter 8: Maintenance, Risk, and SecuritySection 8.1 · lesson 53 of 697 min · free with a free account

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In this lesson

The maintenance phase: its 4 types, its cost, its controls, and its end.

  • Explain what the maintenance phase covers
  • Distinguish corrective, adaptive, perfective, and preventive maintenance
  • Explain why maintenance is usually the largest share of lifetime cost
  • Explain configuration management, change management, and system retirement

Transcript

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Maintenance, Risk, and Security

Keeping Software Alive

Go-live is not the end of a system's story. For most systems, it is closer to the beginning. This section covers the maintenance phase. Its four types, why it costs so much, how changes to a live system are controlled, and how a system is finally retired.

After Go-Live

The Maintenance Phase

Once a system is implemented and delivered, it enters the maintenance phase. That is the ongoing work needed to keep it running, accurate, and useful after go-live. Maintenance is not just fixing the bugs that slipped through testing. It covers everything from correcting a genuine defect, to adjusting the system as its environment changes, to improving it based on how people actually use it. For most systems, this phase runs for years. It is typically far longer than the time it took to build the system in the first place.

Figure 8.1

4 Types of Maintenance

Maintenance work is generally grouped into four types. They sit along a spectrum, from reactive, responding to something that has already gone wrong, to proactive, anticipating a need before it becomes a problem. At the reactive end is corrective maintenance, fixing a defect. Adaptive maintenance follows a change in the system's surroundings. Perfective maintenance improves something that already works. And at the proactive end, preventive maintenance heads off trouble before it arrives.

The 4 Types

What Each One Addresses

Here is what each type addresses, with an example. Corrective maintenance fixes a defect that caused an incorrect result, or a failure. A shipping calculator that charges the wrong rate for one zip code is fixed to charge correctly. Adaptive maintenance adjusts the system to a change in its external environment. Updating a system so it keeps working after the operating system it runs on is upgraded is adaptive. The trigger is outside the system, not a defect in it. Perfective maintenance improves performance or usability based on feedback, with nothing actually broken. Redesigning a confusing checkout screen, after users report it is hard to use, is perfective. Preventive maintenance makes a change now, to reduce the risk of a future problem. Refactoring an outdated, hard-to-modify piece of code before it causes a defect is preventive.

Maintenance Costs

Where Most of the Money Goes

Maintenance is commonly estimated at sixty to eighty percent of a system's total lifetime cost. Initial development makes up the rest. Three factors drive this. Systems stay in use for years, often far longer than anyone originally planned. Their environment keeps changing around them. New regulations, new integrations, and new user expectations, even when the system's core purpose does not change. And years of incremental changes pile up. Code that was once simple becomes harder, and more expensive, to modify safely. Especially if it was poorly documented along the way. Together, these add up to far more total effort than the original build.

Controlling a Live System

Configuration and Change Management

Once a system is live, uncontrolled changes are one of the fastest ways to destabilize it. Two related practices keep maintenance safe. Configuration management tracks and controls exactly which version of each component is running in production. The code, the documentation, and the configuration settings. The team knows precisely what is live at any given moment, so a problem can be traced to a specific, known state. Change management is the formal process for proposing, reviewing, approving, and scheduling a change, before it is made to a live system. A requested change to a live payroll system goes through review and approval before it is deployed, rather than being pushed straight to production. Together, these practices mean a team always knows what is running. And nothing changes in production without someone having reviewed the consequences first.

System Retirement

Ending a System's Life Well

No system stays in maintenance forever. System retirement, or decommissioning, is the formal end of a system's life. It is triggered when the cost or risk of maintaining a system outweighs its remaining value. Often because a replacement has taken over its role. Retiring a system well takes real planning. Data the organization still needs has to be migrated to the replacement, or properly archived. Users have to be transitioned, and if needed, trained on whatever takes the old system's place. The old infrastructure has to be formally shut down, rather than simply abandoned. And any legal or regulatory rules about how long records must be kept have to be satisfied, before old data is finally destroyed.

Key Terms

The Vocabulary of This Section

Let's lock in the key terms. The maintenance phase is the work of keeping a system running, accurate, and useful after go-live. Corrective maintenance fixes a defect. Adaptive maintenance adjusts to a change in the environment. Perfective maintenance improves what already works. Preventive maintenance heads off a future problem. Configuration management tracks exactly what is running in production. Change management is the formal approval process for changes to a live system. And system retirement is the formal, planned end of a system's life.

Key Takeaways

What to Carry Forward

To pull this together. The maintenance phase keeps a system running, accurate, and useful after go-live, and typically lasts far longer than development. Corrective, adaptive, perfective, and preventive maintenance range from reactive to proactive. Maintenance commonly accounts for sixty to eighty percent of a system's total lifetime cost. Configuration management tracks what is running in production. Change management controls how it is changed. And system retirement requires planning for data migration, user transition, infrastructure shutdown, and records retention.

About System Analysis and Design at UPI Study

System Analysis and Design (Computer Science 390) is a self-paced online course of 69 video lessons in 9 chapters, from the analyst's role and requirements to UML modeling, interface and database design, testing, maintenance and project management. It carries a NCCRS credit recommendation for 3 semester credits.

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Universities that work with NCCRS

System Analysis and Design carries a NCCRS credit recommendation. These universities work with NCCRS; some are UPI Study's signed partners. ACE and NCCRS have over 2,100 cooperating colleges that will consider accepting credits; the final decision is with the universities.

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FAQ

Questions students ask us

About Keeping Software Alive: The Maintenance Phase

What are the four types of software maintenance?
The four types are corrective, adaptive, perfective, and preventive maintenance. Corrective fixes a defect, such as a shipping calculator charging the wrong rate. Adaptive adjusts the system to an outside change, such as an operating system upgrade. Perfective improves something that already works, like redesigning a confusing screen. Preventive changes something now, such as refactoring outdated code, to reduce the risk of a future problem.
What is the difference between adaptive and perfective maintenance?
Adaptive maintenance responds to a change in the system's external environment, while perfective maintenance improves a system that is working, based on feedback. Keeping software running after the operating system beneath it is upgraded is adaptive, because the trigger lies outside the system. Redesigning a checkout screen that users find hard to use is perfective, because nothing is broken; the goal is better performance or usability.
Why is maintenance the most expensive part of the software life cycle?
Maintenance costs the most because systems stay in use for years, their environment keeps changing, and accumulated changes make the code harder to modify. It is commonly estimated at 60 to 80 percent of a system's total lifetime cost. Systems often run far longer than planned, new regulations, integrations, and user expectations keep arriving, and incremental changes pile up, especially in poorly documented code, so total effort far exceeds the original build.
What is the difference between configuration management and change management?
Configuration management tracks exactly which version of each component, including code, documentation, and settings, is running in production, while change management is the formal process for proposing, reviewing, approving, and scheduling changes to a live system. Together they mean a team knows what is live at any moment and that a change, such as an update to a payroll system, is reviewed before it is deployed.

About the System Analysis and Design course

How many college credits is System Analysis and Design?
System Analysis and Design (Computer Science 390) carries a NCCRS credit recommendation for 3 semester credits. ACE and NCCRS have over 2,100 cooperating colleges that will consider accepting credits; the final decision is with the universities.
How much does System Analysis and Design cost and what is included?
$250, paid once, with lifetime access: all 69 video lessons, a practice quiz after each, the graded work and final exam, and an official transcript when you finish. Students who want several courses choose UPI Study PRO instead.
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UPI Study has signed partner agreements with universities such as Thomas Edison State University, University of the People and Charter Oak State College, and works with universities such as Penn State, SNHU and SUNY. ACE and NCCRS have over 2,100 cooperating colleges that will consider accepting credits; the final decision is with the universities. Use "Find my college" on this page to check yours.
How long does System Analysis and Design take?
It is self-paced with no deadlines. The 69 lessons total about 9 hours of video; most students add reading and practice time and finish in a few weeks to a few months, on their own schedule.
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Quizzes and assignments are online in the course. The final exam is taken online with proctoring; a person on the UPI Study team checks assignments, usually within two days.
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