RoBuSt: A Crash-Failure-Resistant Distributed Storage System

TL;DR

RoBuSt is a distributed storage system that is provably resistant to crash failures caused by adaptive adversaries, supporting both lookup and write requests with efficient communication, computation, and storage overheads.

Contribution

It extends previous work IRIS to handle both lookup and write requests while maintaining crash-failure robustness against adaptive adversaries.

Findings

Supports up to rac{1}{\,log\, ext{log}\,n} crash failures

Processes requests in polylogarithmic rounds, time, and work

Maintains logarithmic storage overhead

Abstract

In this work we present the first distributed storage system that is provably robust against crash failures issued by an adaptive adversary, i.e., for each batch of requests the adversary can decide based on the entire system state which servers will be unavailable for that batch of requests. Despite up to $\gamma n^{1/\log\log n}$ crashed servers, with $\gamma>0$ constant and $n$ denoting the number of servers, our system can correctly process any batch of lookup and write requests (with at most a polylogarithmic number of requests issued at each non-crashed server) in at most a polylogarithmic number of communication rounds, with at most polylogarithmic time and work at each server and only a logarithmic storage overhead. Our system is based on previous work by Eikel and Scheideler (SPAA 2013), who presented IRIS, a distributed information system that is provably robust against the same kind of crash failures. However, IRIS is only able to serve lookup requests. Handling both lookup and write requests has turned out to require major changes in the design of IRIS.