||Oracle Tips by Burleson
Oracle10g Grid Computing
Chapter 12 - RAC Design Considerations
Failure of the Application Server
application server usually serves the web pages, reports, forms, or
other interfaces to the users of the system. If there is only a single
application server and it goes down, even if the database is fully
functional, there is no application to run against it. A failed
application server without redundancy means no one can use the
database, even if all other components are still functional. This also
applies to single web cache servers or OC4J servers.
Failure of the Database Server
of the database server is the one failure that is taken care of in a
normal RAC configuration. Failure of a single database server leads to
failover of the connections to the surviving node. While not a
critical failure that will result in loss of the system, a single
server failure means a reduction in performance and capacity. Of
course, a catastrophic failure of both servers will result in total
loss of service.
the servers will have disk controllers or interfaces that connect
through the switches to the SAN arrays. These controllers or
interfaces should also be made redundant and have multiple channels
per controller or interface. In addition, multiple network interface
cards (NICs) should also be redundant, with at least a single spare to
take the place of either the network connection card or the cluster
interconnect should a failure occur.
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