|
As people increasingly count on computers, the reliability of
the computer become more and more important. Using high-
quality components cannot effectively increase the
reliability of the system. Therefore, to achieve higher
reliability, we have to add fault-tolerant technologies to
the system in the design. The redundancy components are
used in both hardware and software fault-tolerant
technologies that meet basic goal of fault tolerance,
that is, to perform the intended function actions even in the
presence of faults or unexpected conditions. Presently, the
hardware fault-tolerant technologies are pretty mature, but
there is no standardization, also these products for
special purpose are expensive. As for high availability
applications, for example, Intelligent Network, how to reduce
the system cost while still meet realistic needs is a major
concern. In this thesis, we propose a fault-tolerant
architecture through loosely coupled multicomputers for
building a high availability system, through it both software
and hardware fault tolerance can be achieved simultaneously.
The system architecture is not only cost saving but also
implementation feasible. The configuration includes two
computers linked by FDDI network, if the active computer or
the application fails, a corresponding standby one can take
over the task and continue to provide the services. We use
Markov process to model the method and evaluate the
reliability and availability of the system. We also discuss
the relationship between the improvement of the system and
the number of alternates in the application. We use a 080
freephone service as a scenario to demonstrate the system.
|