Answer 5_7_5

Question 5

State three different types of maintenance.  Explain why maintenance is such a high proportion of the cost of running software.

• Corrective maintenance - gets rid of bugs that might take time to show up.  Often this is done by downloading corrective patches from websites;
• Adaptive maintenance - systems may be adapted to changing requirements, for example changing single-user software to multi-user software.  A new operating system may require some adaptive maintenance to be done;
• Perfective maintenance - the system can be made to work even better without changing its functionality.  For example reports can be made in a clearer format.

Reasons for expense include:

• Maintenance is time consuming;
• The code may not be clear.
• Documentation can be poor.
• Bigger errors can occur due to ham-fisted maintenance by less experienced staff.

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