Rada deh & Al-Ameed
Copyright ?© 2007, Idea Group Inc. Copying or distributing in print or electronic forms without written permission
of Idea Group Inc. is prohibited.
With the concept of using an N+1 configuration (N active nodes with 1 spare node), it
provides a very flexible and cost effective clustering scenario to enable highly available
applications. As an instance, with a four-node cluster in an N+1 configuration, you can have
three of the four nodes set up to actively provide different services while the fourth node is
a passive node that is ready to assume the services of any of the three active nodes in the
event of a server failure.
Clustering is powerful, but not all database clustering is the same. There are as many implementations
as there are databases. The costs of these vary significantly, and many vendors
leave too many of the practical issues of clustering up to the application programmers,
which significantly impacts the cost and complexity of the solution (Choosing the Right
Database, 2004). Even among databases that provide clustering, many of the challenges of
clustering are not addressed in the design of the database. Instead, the expectation is that
application designers will do the necessary programming to make it to work.
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