Availability Guide for Problem Management

Availability Guide for Problem Management–125509
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Preventing Unplanned Outages
Overview
When unplanned outages occur, systems or applications may become unavailable to the
end user. By preventing unplanned outages, you will move closer to the goal of 24-hour-
a-day, 7-day-a-week, 365-day-a-year (24x7x365) operations.
This section defines unplanned outages and describes types of unplanned outages that
can affect the availability of your system. After reading this section, you should be able
to manage your operations in a way that minimizes unplanned outages and the impact
they have on applications and end users.
What Is an Unplanned Outage?
An unplanned outage is a period of time during which a system or application is
unavailable to its end users because of an unexpected or unavoidable problem such as
faulty hardware, design error, operator error, or environmental disaster.
Outage Classes
Tandem classifies unplanned outages using a scheme based on International Federation
of Information Professionals (IFIP) fault classifications. Following this scheme, every
unplanned outage falls in one of these categories, according to its cause:
Physical Caused by mechanical or electrical failure of a properly designed
hardware component
Design Caused by an error in the design of a hardware component or in
the design of software running on that component
Operations Caused by accidental, uninformed, or malicious action on the part
of a system operator or other operations management personnel
Environmental Caused by uncontrollable environmental conditions, including loss
of electrical power, temperature extremes, and flooding