Customers are also looking to information technology strategies for ways to more effectively run their businesses and to create strategic competitive differentiation. Without high availability, new business strategies will not be able to develop to their full potential. System availability is often measured as the percentage of time a system is able to be used for its intended purposes. Each time period a system is unavailable is known as an outage. For practical system analysis, outages should include both planned and unplanned outages.
Planned outages are due to such scheduled activities as services, upgrades and reconfiguration.
Planned outages typically can account for significantly more downtime than unplanned outages. As such, planned outages should not be overlooked in system availability analysis. The level of availability required is a business decision, dictated by a customer's IT strategy. Achieving a higher level of availability generally requires appropriate planning, organizational process and training, maintenance and system architectures designed to support the specific availability requirements. As shown in the following figure, some applications may be well served by standard availability offerings.