A feedback-based adaptive data migration method for hybrid storage VOD caching systems

摘要

Nowadays Video-On-Demand (VOD) caching systems are often equipped with hybrid storage devices, which have been designed to combine the high read speed of Solid State Disks (SSDs) and the large capacity of Hard Disk Drives (HDDs). However, the number of erase cycles of SSDs is limited. So it is important to control the write load of SSDs in real applications. This paper proposes a Feedback-based Adaptive Data Migration (FADM) method, which can utilize the real-time feedback of the write load of SSDs to adjust the rule of moving data between HDDs and SSDs. More specifically, a video in HDDs is allowed to be moved into SSDs when its popularity is higher than that of the least popular video in SSDs by a threshold. This threshold is adaptively adjusted according to the feedback of the write load of SSDs. With FADM, the desired lifetime of SSDs can be well guaranteed even under various user behaviors while good read performance can be maintained. Simulations are done to demonstrate the effectiveness of FADM.