Availability can mean different things for different organizations. For this discussion,
we??™ll consider a system to be available when it is up (meaning that the database
can be accessed by users) and working (meaning that the database is delivering the
expected functionality to business users at the expected performance).
Most businesses depend on data availability. More recently, accessibility to data via
web-based solutions means that database failures can have an even more dramatic
impact on business. Failures of such systems accessed by a wider community outside
of company boundaries are, unfortunately, immediately and widely visible and
can seriously impact a company??™s financial health and image. Consider the webbased
customer service provided by package shipping companies that enable customers
to perform package tracking. As these customers come to depend on such service, interruptions
in that service can cause these same customers to move to competitors.
Taking this a step further, consider complexities in accessing data that resides in
multiple systems.
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