Abstract
Most of the video on demand (VOD) servers utilize conventional hard disk drives (HDDs) to keep huge number of video files. Large-scale VOD servers need to provision a large number of concurrent requests with fast response time. However, improving the performance of VOD server has become so obstructive and limited due to high latency of the disk access and low I/O operation of the magnetic HDDs. By contrast, flash-based solid-state drive (SSD) has fast access reading and provides large I/O operation per second that makes it as an interesting alternative choice. Nevertheless, using SSD instead of the entire HDD is very expensive due to SSD costs high in price per gigabyte. Accordingly, combination of HDD and SSD can enhance the performance of the storage subsystem of a VOD server in a cost-effective way. In this paper, hybrid storage system (HSS) is proposed in VOD server in order to increase the number of simultaneous user requests and decrease startup latency in an economic way. The top 10% of popular videos are kept in SSD to exploit its fast access for read-intensive workloads. Our results show that the design of our proposed HSS produces high performance than the conventional VOD HDD-based server which the enhancement in the average total response times for all different request sizes by 65%. Also, the throughput is enhanced by 200%.