Publications by Nuno Filipe de Sousa Santos

Recovery Algorithms for Paxos-Based State Machine Replication

André Schiper, Nuno Filipe de Sousa Santos

In this article, we propose and evaluate three different state recovery algorithms aimed for Paxos-one of the most popular distributed agreement protocols. Paxos is commonly used to maintain consistency among state machine replicas despite of failures of p ...

IEEE COMPUTER SOC2021

Achieving high-throughput State Machine Replication in multi-core systems

André Schiper, Nuno Filipe de Sousa Santos

The traditional architecture used by implementations of Replicated State Machines (RSM) does not fully exploit modern multi-core CPUs. This is increasingly the limiting factor in their performance, because network speeds are increasing much faster than the ...

Ieee2013

Optimizing Paxos with batching and pipelining

André Schiper, Nuno Filipe de Sousa Santos

Paxos is probably the most popular state machine replication protocol. Two optimizations that can greatly improve its performance are batching and pipelining. However, tuning these two optimizations to achieve high-throughput can be challenging, as their e ...

Elsevier2013

State Machine Replication : from Analytical Evaluation to High-Performance Paxos

Nuno Filipe de Sousa Santos

Since their invention more than half a century ago, computers have gone from being just an handful of expensive machines each filling an entire room, to being an integral part of almost every aspect of modern life. Nowadays computers are everywhere: in our ...

EPFL2012

S-Paxos: Offloading the Leader for High Throughput State Machine Replication

André Schiper, Zarko Milosevic, Nuno Filipe de Sousa Santos, Martin Biely

Implementations of state machine replication are prevalently using variants of Paxos or other leader-based protocols. Typically these protocols are also leader-centric, in the sense that the leader performs more work than the non-leader replicas. Such prot ...

2012

Quantitative Analysis of Consensus Algorithms

André Schiper, Martin Hutle, Fatemeh Borran, Nuno Filipe de Sousa Santos

Consensus is one of the key problems in fault-tolerant distributed computing. Although the solvability of consensus is now a well-understood problem, comparing different algorithms in terms of efficiency is still an open problem. In this paper, we address ...

2012

Tuning Paxos for high-throughput with batching and pipelining

André Schiper, Nuno Filipe de Sousa Santos

Paxos is probably the most popular state machine replication protocol. Two optimizations that can greatly improve its performance are batching and pipelining. Nevertheless, tuning these two optimizations to achieve high-throughput can be challenging, as th ...

2012

Swift Algorithms for Repeated Consensus

André Schiper, Martin Hutle, Fatemeh Borran, Nuno Filipe de Sousa Santos

We introduce the notion of a swift algorithm. Informally, an algorithm that solves the repeated consensus is swift if, in a partial synchronous run of this algorithm, eventually no timeout expires, i.e., the algorithm execution proceeds with the actual spe ...

Ieee Computer Soc Press, Customer Service Center, Po Box 3014, 10662 Los Vaqueros Circle, Los Alamitos, Ca 90720-1264 Usa2010

Latency-aware Leader Election

André Schiper, Martin Hutle, Nuno Filipe de Sousa Santos

Experimental studies have shown that electing a leader based on measurements of the underlying communication network can be beneficial. We use this approach to study the problem of electing a leader that is eventually not only correct (as aptured by the fa ...

ACM2009

Security in distributed metadata catalogues

Nuno Filipe de Sousa Santos

Catalogue services provide the discovery and location mechanisms that allow users and applications to locate data on Grids. Replication is a highly desirable feature in these services, since it provides the scalability and reliability required on large dat ...

2008