Conclusion

Due to their poor locality, high update rates, lack of idle time, and high reliability requirements, transaction processing application such as those exemplified by TPC-C are among the most demanding I/O applications. In this paper, we have explored how to integrate eager-writing, mirroring, and striping in a eager-writing disk array design that effectively caters to the need of these applications. Mirroring and striping improves read performance, while eager-writing improves write performance and reduces the cost of data replication. The combination provides a high degree of reliability without imposing excessive performance penalty. To fully realize the potential of an EW-Array, we must address two issues. One is the careful balance of extra disk capacity that is devoted to each of the three dimensions: free space dilution for eager-writing, the degree of mirroring, and the degree of striping. The second is the intelligent scheduling of the queued requests so that the flexibility afforded by the high degree of location independence associated with eager-writing is fully exploited. Simulation and implementation results indicate that the prototype EW-Array can deliver latency and throughput results unmatched by conventional approaches for an important class of transaction processing applications.