Research results can be found in the following publications:

Eduardo Alchieri Alysson Bessani, João Sousa. ...and state machine replication for all with bft-smart. In Proc. 7th ACM SIGOPS/EuroSys European Systems Conference (EuroSys'12). Poster Session, 2012.
P. Ferreira. Diverse intrusion-tolerant database replication. Master's thesis, FCUL/CMU, 2012.
J. Paulo, P. Reis, J. Pereira, and A. Sousa. Dedisbench: A benchmark for deduplicated storage systems. In Intl. Symp. Distributed Objects, Middleware, and Applications - Secure Virtual Infrastructures (DOA-SVI). Springer, 2012.
João Sousa and Alysson Bessani. From byzantine consensus to bft state machine replication: A latency-optimal transformation. In Proc. of the 9th European Dependable Computing Conference - EDCC'12, 2012.
M. Araújo. Database replication in large scale systems. Master's thesis, U. Minho, 2011.
Alysson Bessani, Miguel Correia, Bruno Quaresma, Fernando André, and Paulo Sousa. Depsky: Dependable and secure storage in a cloud-of-clouds. In Proceedings of the 6th ACM SIGOPS/EuroSys European Systems Conference (EuroSys), 2011.
J. Bordalo. Minha: Avaliação realista de aplicações distribuídas num ambiente centralizado. Master's thesis, U. Minho, 2011.
N. A. Carvalho, J. Bordalo, F. Campos, and J. Pereira. Experimental evaluation of distributed middleware with a virtualized java environment. In MW4SOC '11: Proceedings of the 6th workshop on Middleware for service oriented computing, 2011.
P. Gomes. Migração de aplicações legadas para bases de dados nosql. Master's thesis, U. Minho, 2011.
P. Gomes, J. Pereira, and R. Oliveira. An object mapping for the cassandra distributed database. In INForum – Simpósio de Informática, 2011.
R. Posse. Serviço de coordenação para bases de dados replicadas. Master's thesis, U. Lisboa, 2011.
J. Paulo and J. Pereira. Model checking a decentralized storage deduplication protocol. In Fifth Latin-American Symposium on Dependable Computing (LADC), 2011.
Luís Soares and José Pereira. Improving the scalability of cloud-based resilient database servers. In Distributed Applications and Interoperable Systems (DAIS, with DisCoTec), number 6723 in LNCS. Springer, 2011.
Miguel Araújo and José Pereira. Evaluating data freshness in large scale replicated databases. In INForum – Simpósio de Informática, 2010.
Alysson Bessani, Miguel Correia, and Paulo Sousa. Active quorum systems. In Proceedings of the Workshop on Hot Topics in System Dependability (HotDep), 2010.
A. Correia Jr. Pratical Database Replication. PhD thesis, U. Minho, 2010.
Francisco Maia, José Enrique Armendáriz-Iñigo, M. I. Ruiz-Fuertes, and Rui Oliveira. Scalable transactions in the cloud: Partitioning revisited. In Intl. Symp. Distributed Objects, Middleware, and Applications (DOA), number 6427 in LNCS. Springer, 2010.

Previous Results

You can find preliminary research results leading to the proposed approach in the following publications:

Paulo Sousa, Alysson Neves Bessani, Miguel Correia, Nuno Ferreira Neves, and Paulo Verissimo. Highly available intrusion-tolerant services with proactive-reactive recovery. IEEE Transactions on Parallel and Distributed Systems, 21(4):452–465, 2010. (doi:10.1109/TPDS.2009.83)
Luís Soares and José Pereira. Do-it-yourself shared-storage cluster with an off-the-shelf DBMS. In In "Fast Abstract", Supplement of the 39th Annual IEEE/IFIP International Conference on Dependable Systems and Networks. IEEE, 2009.
Luís Soares and José Pereira. A simple approach to shared storage database servers. In WDDDM'09: Proceedings of the Third Workshop on Dependable Distributed Data Management (with EuroSys), pages 21–24. ACM, 2009. (doi:10.1145/1518691.1518698)
Alysson Neves Bessani, Eduardo Pelinson Alchieri, Miguel Correia, and Joni da Silva Fraga. Depspace: A byzantine fault-tolerant coordination service. In Proceedings of the 3rd ACM SIGOPS/EuroSys European Systems Conference - EuroSys 2008, April 2008. (doi:10.1145/1357010.1352610)