Streaming RAID

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.