Fork Sequential Consistency is Blocking

TL;DR

This paper proves that it is impossible for a storage protocol to simultaneously guarantee sequential consistency, wait-freedom, and fork sequential consistency when using an untrusted server.

Contribution

It establishes a fundamental impossibility result linking sequential consistency, wait-freedom, and fork sequential consistency in untrusted storage systems.

Findings

No protocol can ensure both sequential consistency and fork sequential consistency with wait-freedom.

The impossibility holds even when the server is correct.

Highlights fundamental limitations in designing reliable untrusted storage protocols.

Abstract

We consider an untrusted server storing shared data on behalf of clients. We show that no storage access protocol can on the one hand preserve sequential consistency and wait-freedom when the server is correct, and on the other hand always preserve fork sequential consistency.