USENIX 2002 Annual Conference - Technical Program Abstract
Maximizing Throughput in Replicated Disk Striping
of Variable Bit-Rate Streams
Stergios V. Anastasiadis, Department of Computer Science, Duke University; Kenneth C. Sevcik, Department of Computer Science, University of Toronto; Michael Stumm, Dept of Electrical and Computer Engineering, University of Toronto
In a system offering on-demand real-time streaming of media files, data
striping across an array of disks can improve load balancing, allowing
higher disk utilization and increased system throughput. However, it can
also cause complete service disruption in the case of a disk failure. Reliability
can be improved by adding data redundancy and reserving extra disk bandwidth
during normal operation. In this paper, we are interested in providing
fault-tolerance for media servers that support variable bit-rate encoding
formats. Higher compression efficiency with respect to constant bit-rate
encoding can significantly reduce per-user resource requirements, at the
cost of increased resource management complexity. For the first time, the
interaction between storage system fault-tolerance and variable bit-rate
streaming with deterministic QoS guarantees is investigated. We implement
into a prototype server and experimentally evaluate, using detailed simulated
disk models, alternative data replication techniques and disk bandwidth
reservation schemes. We show that with the minimum reservation scheme introduced
here, single disk failures can be tolerated at a cost of less than 20%
reduced throughput during normal operation, even for a disk array of moderate
size. We also examine the benefit from load balancing techniques proposed
for traditional storage systems and find only limited improvement in the
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