Service Rate Region: A New Aspect of Coded Distributed System Design

TL;DR

This paper introduces the concept of service rate region in erasure-coded distributed systems, highlighting its importance in system design and analyzing how different codes affect the system's capacity to handle data requests.

Contribution

It characterizes the service rate regions for various codes and explores code design strategies to optimize system capacity and request handling.

Findings

Characterized rate regions of MDS, LRC, and Simplex codes.

Demonstrated effectiveness of hybrid replication-erasure codes.

Connected multi-set batch codes to maximizing service rate regions.

Abstract

Erasure coding has been recognized as a powerful method to mitigate delays due to slow or straggling nodes in distributed systems. This work shows that erasure coding of data objects can flexibly handle skews in the request rates. Coding can help boost the \emph{service rate region}, that is, increase the overall volume of data access requests that the system can handle. This paper aims 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, and2) 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. We show the effectiveness of hybrid codes that combine replication and erasure coding in terms of code design. We also discover fundamental connections between multi-set batch codes and the problem of maximizing the service rate region.