Streaming RAID: a disk array management system for video files

Abstract

The characteristics of digital video files and traffic differ substantially from those encountered with data applications: (i) video files are much larger than data files, and (ii) video traffic is continuous in nature while data traffic is bursty, with the data rate of a video stream much higher than the mean rate of a data traffic source. Accordingly, conventional file servers and associated storage systems are not well suited to support video services over local area networks; instead, new servers capable of handling the specific characteristics of video files and traffic are needed. In this paper, we describe a video applications server software called StarWorks ™ , focusing primarily on its underlying storage management system. The latter manages an array of Winchester disks, and uses a disk access algorithm particularly suitable for video streaming, and is thus referred to as " Streaming RAID ". We also characterize the performance of the system by determining the number of streams that can be supported for a given memory size and a given start-up latency requirement.