Analysis of Prediction and Replacement Algorithms Applied to Real Workload for Storage Devices

Abstract

This work evaluates cache algorithms for block devices in terms of hit rate for different replacement and prediction algorithms, and also focuses on choosing suitable replacement and prediction strategies to be implemented in a storage array caching solution employing solid-state drives. As case study, a real workload was continuously collected from web proxy server network. Such replacement and prediction algorithms were evaluated in detail and compared between them considering traced SCSI commands collected from Linux kernel. Comparison results for replacement algorithms LRU, CLOCK, LRFU and LRU-WAR applied to real workload indicates that LRU obtained good results in the majority of the cases. GHB and ReadAhead prefetching algorithms also were integrated and improvements of about 5.5% were achieved when ReadAhead was used.