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Computer Science Colloquia

Tuesday, May 10, 2011
Abhishek Rawat
Advisor: Sudhanva Gurumurthi
Attending Faculty: Kevin Skadron, Chair

Olsson 236D, 10:00:00

A Master's Project Presentation
Accelerating Reliability Simulations for NAND Flash based Solid State Disks

Software based storage system simulators have been used for studying performance characteristics of different SSDs. Unlike performance characteristics which can be accurately measured by simulating I/O activity over a relatively short time period (e.g., a day), accurately measuring the reliability properties require simulating an SSD for at least 5 - 10 years, which is the expected retention time for storage. Simulating such a long period of time takes several days to even weeks or months for realistic workloads. In this work we examine this problem and optimize Microsoft Research's Disksim SSD extension, a popular SSD simulator, to speedup the simulation time. We also show that by skipping read requests, which do not contribute to the reliability metrics of concern, we can improve simulation time, albeit at the cost of accuracy. Using a set of workload traces obtained from Microsoft data centers, we show a simple approach to skipping reads that improves simulation time with low error rates.  We show that we can improve simulation time by approximately 50% for the most write intensive workload and approximately 85% for the most read intensive workload.