As with normal operating systems, server cluster
applications run on top of an abstract cluster interface to
isolate the application from hardware changes and to
isolate faults in one application from affecting other
applications in the same data center.
– For fault tolerance and scale, many web sites are implemented
on distributed clusters of computers housed in one or more
geographically distributed data centers.
– If one computer fails due to a hardware fault, software crash, or
power failure, another computer can take over its role.
– If demand for the web site exceeds what a single computer can
accommodate, web requests can be partitioned among multiple
machines.