Minimization of buffer requirements using variable-size parity groups for fault-tolerant video servers

In this paper we propose storage allocation schemes to minimize the buffer requirements for fault-tolerant video-ondemand (VOD) servers with disk arrays. To guarantee the high reliability of video service, the servers usually adopt parity-encoding techniques in which data blocks and their associated parity block form a parity group. For real-time video service, all the blocks in a parity group are prefetched to cope with disk failure. Buffer overhead incurred by a prefetch can be reduced by decreasing the parity group size, which demands more storage space for parity blocks. Our proposed scheme called Round-level Parity Grouping (RPG) aims at restoring VBR video streams efficiently. Based on RPG we have developed a heuristic algorithm working towards effective buffer management. The experimental results show that our proposed schemes produce near-optimal buffer requirements.