Integrated Error Management for Media-on-Demand Services

Data servers for multimedia applications like News-onDemand represent a severe bottleneck, because a potentially (very) high number of users concurrently retrieve data with high data rates. In the Intermediate Storage Node Concept (INSTANCE) project, we develop a new architecture for Media-on-Demand servers that maximizes the number of concurrent clients a single server can support. Traditional bottlenecks, like copy operations, multiple copies of the same data element in main memory, and checksum calculation in communication protocols are avoided by applying three orthogonal techniques: zero-copy-one-copy memory architecture, network level framing, and integrated error management. In this paper, we describe design, implementation, and evaluation of our integrated error management mechanism. Our results show that the reuse of parity information from a RAID system as forward error correction information in the transport protocol reduces the server workload and enables smooth playout at the client.