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As the measurement and analytical results indicate, if the number
of client nodes is smaller than the number of server nodes,
server-driven protocols tend to have a higher write performance
than the client-driven protocols since more nodes are involved in
sharing the duplication work. Between the server driven protocols,
the synchronous one is preferred because it has a higher
reliability with only slightly lower bandwidth. On the contrary,
if the total number of the client nodes is greater than that of
the server nodes, the client-driven protocols are better than
their server-driven counterparts. Between the client-driven
protocols, the asynchronous client duplication is the most
favorable since it has the highest write performance and the
second best reliability. These observations lead us to propose a
hybrid protocol to optimize the tradeoff between the reliability
and bandwidth performances.
A scientific application is usually required to specify the total
number of parallel jobs or clients it needs before running in a
cluster. In the hybrid duplication protocol, each client compares
the total server number in one storage group with the total number
of parallel clients of the current application. If the server
number exceeds the client number, the synchronous server
duplication is used to mirror the data. Otherwise, the
asynchronous client duplication is preferred. In this way, this
hybrid protocol always tries to achieve a considerably high write
performance or reliability with little degradation of the other.
Next: Conclusion and Future Work
Up: Reliability and Availability Analysis
Previous: Availability Analysis
Yifeng Zhu
2003-10-16