SAIL: self-adaptive file reallocation on hybrid disk arrays

Flash-memory based solid state disks, though currently more expensiveand inadequate in write cycles, offer much faster read accesses while consumemuch less energy compared with hard disk drives. In order to gain complementarymerits of hard disks and flash disks, we propose a hybrid disk array based storagearchitecture for data-intensive server-class applications. Further, on top of the proposedstorage architecture, a self-adaptive file reallocation strategy, called SAIL,which is able to adapt to dynamically changed file access patterns, is developed.Comprehensive trace-driven experiments demonstrate that compared with a veryrecent file placement technique PB-PDC, which also employs the combined advantagesof a hard disk and a flash memory device, SAIL exhibits its strength in bothperformance and energy consumption while maintains the reliability of flash disksby confining their write cycles.