Service Rate Region: A New Aspect of Coded Distributed System Design
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Erasure coding has been recently employed as a powerful method to mitigate delays due to slow or straggling nodes in distributed systems. In this work, we show that erasure coding of data objects can flexibly handle skews in the request rates. Coding can help boost the service rate region, that is, increase the overall volume of data access requests that can be handled by the system. The goal of this paper is to postulate the service rate region as an important consideration in the design of erasure coded distributed systems. We highlight several open problems that can be grouped into two broad threads: 1) characterizing the service rate region of a given code and finding the optimal request allocation, and 2) designing the underlying erasure code for a given service rate region. As contributions along the first thread, we characterize the rate regions of maximum-distance-separable, locally repairable, and Simplex codes. In terms of code design, we show the effectiveness of hybrid codes that combine replication and erasure coding, and also discover fundamental connections between multi-set batch codes and the problem of maximizing the service rate region.
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