Flash memory file caching for mobile computers

We examine the impact of using flash memory as a second-level file system buffer cache to reduce power consumption and file access latency on a mobile computer. We use trace-driven simulation to evaluate the impact of what we call a FLASHCACHE. We relate the power consumption and access latency of the storage sub-system to the characteristics of the FLASHCACHE: its size, the unit of erasure, and access costs. We find that a FLASHCACHE can reduce the power consumption of the storage subsystem by 20-40% and can improve overall response time by 30-70% when combined with an aggressive disk management policy. When combined with a more conservative policy, power is reduced from 40-70% while overall response time is improved 20-60%. We also find that durability is not a problem; a 4 MB FLASHCACHE will last 33 years.<
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