Cleaning Policies in Mobile Computers Using Flash Memory1

Flash memory shows promise for use in storage devices for mobile computers. However, flash memory cannot be overwritten unless erased in advance. Erase operations are slow that usually decrease system performance, and consume power. For power conservation, better system performance, and longer flash memory lifetime, system support for erasure management is necessary. In this report, a non-update-inplace scheme is proposed to implement a flash memory server. A new cleaning policy is used to reduce the number of erase operations and to evenly wear out flash memory. The policy uses a fine-grained method to effectively cluster hot data and cold data in order to reduce cleaning overhead. Performance evaluations show that erase operations are significantly reduced and flash memory is evenly worn.