Disk placement for arbitrary-rate playback in an interactive video server

Abstract

Multimedia data, especially continuous media including video and audio objects, represent a rich and natural stimulus for humans, but require large amount of storage capacity and real-time processing. In this paper, we describe how to organize video data efficiently on multiple disks in order to support arbitrary-rate playback requested by different users independently. Our approach is to segment and decluster video objects and to place the segments in multiple disks using a restricted round-robin scheme, called prime round-robin (PRR). Its placement scheme provides uniform load balance of disks for arbitrary retrieval rate as well as normal playback, since it eliminates hot spots. Moreover, it does not require any additional disk bandwidth to support VCR-like operations such as fast-forward and rewind. We have studied the various effects of placement and retrieval schemes in a storage server by simulation. The results show that PRR offers even disk accesses, and the failure in reading segment by deadline occurs only at the beginning of new operations. In addition, the number of users admitted is not decreased, regardless of arbitrary-rate playback requests.

Supporting Dynamic Relocation of Video Data in Disk-Array-Based Video Servers

“…If a seg- Figure 2: Impact of Accessing Modified Video Object ment consists of a fixed number of frames, segments vary in size and the uniform load-balance of disks is not achieved in segment-based placement schemes. In [4], we have extended the disk placement scheme to apply VBR compression. In this paper, however, we concentrate on relocation method associated with general segment-based disk placement.…”

“…Moreover, to support variable-rate concurrent playbacks, one must resolve the concentration phenomena of resources in particular disks. As proposed in [4,5,6], we have concentrated on a disk placement method in which the video storage system distributes video segments evenly on multiple disks for playback at any desired speed in order to ensure uniform loadbalance of multiple disks. It is clear that the storage system in multimedia databases should support not only playback but also modification of video clips such as insertion and deletion.…”