IRWIN AND JOAN JACOBS CENTER FOR COMMUNICATION AND INFORMATION TECHNOLOGIES Dynamic Atomic Storage Without Consensus

This paper deals with the emulation of atomic read/write (R/W) storage in dynamic asynchronous mes-sage passing systems. In static settings, it is well known that atomic R/W storage can be implemented in afault-tolerant manner even if the system is completely asynchronous, whereas consensus is not solvable.In contrast, all existing emulations of atomic storage in dynamic systems rely on consensus or strongerprimitives, leading to a popular belief that dynamic R/W storage is unattainable without consensus.In this paper, we specify the problem of dynamic atomic read/write storage in terms of the interfaceavailable to the users of such storage. We discover that, perhaps surprisingly, dynamic R/W storageis solvable in a completely asynchronous system: we present DynaStore, an algorithm that solves thisproblem. Our result implies that atomic R/W storage is in fact easier than consensus, even in dynamicsystems.