Chapter 13. Availability Metrics

Imagine you are in the middle of a stock transaction on the Internet and then the application hangs for more than half an hour. Or, it is Friday morning and you are running your quarter-end financial report, which is due Monday, and your system crashes and stays down for 96 hours. Or, you are doing a business transaction on a well-known web site and the server supporting it crashes, rendering the site unavailable for a prolonged time. Scenarios such as these are far more frequent than desirable and are incurring costs and decreasing productivity.

The following was from a financial news posted on the Netscape Web site not long ago:

Nasdaq will extend trading for one hour today, to 5 P.M. EDT, after a network problem ...

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