Availability Guide for Application Design

Instrumenting an Application for Availability
Availability Guide for Application Design—525637-004
8-7
What Is Instrumentation and Why Is It Necessary?
What Is Instrumentation and Why Is It
Necessary?
Instrumentation provides the interfaces between objects in the system and operations
utilities that monitor and control these objects. To facilitate this control, HP subsystems
and user applications must:
•
Generate events to indicate state changes in objects they control.
•
Provide an interface for accepting commands from management applications and
provide responses to those commands.
Figure 8-1 on page 8-7 shows a simplified operations management model featuring
instrumented interfaces.
Why Is Instrumentation Necessary?
Even after you have installed the most reliable commercially available computer
system and followed correct application design principles, end users can still lose the
availability of the application for a variety of reasons such as:
•
A disk is full
•
All Transaction Management Facility (TMF) audit-trail files
are full
•
An error was made in the checkpoint logic of a process pair
•
A programming error stops the primary process and the same error stops the
backup after takeover
•
An operational or procedural error has stopped a critical application component
Instrumentation provides the means for anticipating or detecting these kinds of
problems and, in many cases, can help to apply a speedy solution. While HP provides
instrumentation for most system-level subsystems, as many potential problems exist in
the application itself that might take the application offline. Hence, to be sure that
application downtime is kept to a minimum, HP recommends that you apply
instrumentation to all critical modules in your application.
Figure 8-1. Instrumented Operations Management Model
Management
Application
Managed
Objects
Managing System Managed Subsystem
Commands
Responses
Events
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