Installability Requirements

Definition

An installability requirement is a utility requirement that specifies a required amount of installability, which is a quality factor that is defined as follows:

Installability

adj.[quality factor] the ease with which something can be successfully installed in its production environment(s).

Objectives

The typical objectives of an installability requirement are to:

• Ensure that the application or component is easy to install.
• Ensure that time and money are not wasted during the installation process.
• Improve the morale of the engineers that will install the application or component.
• Minimize installation defects.

Examples

The following are typical examples of installability requirements:

• “The average effort required by a typical well-staffed and trained deployment team to install the application shall not exceed 16 person-days.”
• “The average effort required by a typical user to install the application shall not exceed 15 minutes.”

Guidelines

The following guidelines have been found to be useful when producing installability requirements:

• The scope of an installability requirement can be:
  • An application
  • A component
• Installability is typically specified in terms of the maximum average amount of person-hours required for trained operators and/or hardware engineers to perform the installation (including any associated informal testing) in accordance with the associated installation manual.
• Installability requirements can be validated during the delivery phase by observing the performance of the application and component installation tasks of the deployment activity. However, these tasks need to be repeated a statistically significant number of times to determine a reasonable lower limit on the average installation time.
• Installability requirements are especially important when dealing with:
  • Packages software applications that are to be installed by relatively untrained users or customer personnel.
  • Applications with extremely high operational availability requirements (because of the occasional need to reinstall applications or components that have failed).