Availability is the absence of outages. Standard performance benchmarks, and even detailed measurements of system performance based on specific workloads, provide no direct insight into availability levels. Such benchmarks do not indicate how prone a system will be to outages, nor what it will cost to prevent outages.

Even in a relatively protected data center environment, outages have a wide range of common causes. These include bugs in system and applications software, hardware and network failures, as well as operator errors. When computing resources are moved closer to end users, user error also becomes a major source of disruptions.

Production environments contain large numbers of interdependent hardware and software components, any of which represents a potential point of failure. Even the most reliable system experiences some failures.

Thus, maintaining high availability levels may require specialized equipment and software, along with procedures to mask the effects of outages from users and enable service to be resumed as rapidly as possible with minimum disruption to applications and loss of data. The less reliable the core system, the more such measures will be necessary.

Availability can be realized at several levels. Subsystem duplexing and resilient system designs have cost premiums. For example, to move from the ability to restart a system within 30 minutes to the ability to restart within a few minutes can increase costs by orders of magnitude.

Project Management Made Easy

Project Management Made Easy

What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.

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