DIverse DatabasE ReplicatiOn - Performance Comparison (DIDERO-PC)

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This proposal is about experimental evaluation of diverse database replication protocols. It aims at comparing the performance of several database replication protocols, which protect against non-crash failures and are based on use of diverse, i.e. different by design, database management systems (DBMSs). These DBMSs are developed by different vendors, and can be either commercial (e.g. Microsoft SQL Server, Oracle), or open-source products (e.g. MySQL, PostgreSQL). The experimental evaluation will be conducted using two approaches: a model-based approach and a direct experimentation on a testbed with "real" systems.Diverse database replication protocols have a potential of providing higher dependability assurance than traditional approaches that are based on the use of the DBMSs from the same vendor (research from the Centre for Software Reliability (CSR) at City University London has contributed significantly to that finding). However, besides achieving appropriate dependability level, system designers and other DBMS stakeholders are interested in the performance characteristics offered by alternative solutions. For many applications performance is, in fact, the dominant criterion in the selection process.A fair and thorough performance comparison between database replication protocols, including the ones studied in this proposal, is of great benefit to system designers when making decisions about which one is most suitable to integrate in their system. This is the main motivation of the proposal.The project aims at comparing the performance of three database replication protocols which guard against non-crash failures and are based on use of diverse DBMSs: our DivRep (the reference point), SES and Byzantium. There are two main objectives of the particular performance evaluation to be achieved:- Objective 1 - evaluation based on using "real" systems on an experimental testbed, i.e. using respective implementations of the replication protocols together with the real DBMSs.- Objective 2 - model-based evaluation, whereby each replication protocol, as well as DBMS resources, are represented with a suitable model (implemented in a particular tool of choice) and the protocol performance measured by simulation of the respective model.Performance comparison of DBMSs and related replication protocols is too often based only on the comparison that uses (synthetic) benchmarks, which in most cases do not reflect the operational profile of the system under test. In addition, there are limits to what one can achieve with performance comparison based only on experimental evaluation with "real" systems: one can feasibly explore only a limited range of parameter values (such as number of replicas, ratio between read and write operations, etc). In contrast, model-based approach offers greater flexibility by providing means for evaluation with a wide range of configuration parameters in a practical manner. Therefore, the proposal aims at satisfying the following objective:- Objective 3 - provision of a general-purpose methodology for model-based performance evaluation of database replication protocols.