Performance Evaluation of Large-scale Information Retrieval Systems Scaling Down

The performance evaluation of an IR system is a key point in the development of any search engine, and specially in the Web. In order to get the performance we are used to, Web search engines are based on large-scale distributed systems and to optimise its performance is an important aspect in the literature. The main methods, that can be found in the literature, to analyse the performance of a distributed IR system are: the use of an analytical model, a simulation model and a real search engine. When using an analytical or simulation model some details could be missing and this will produce some differences between the real and estimated performance. When using a real system, the results obtained will be more precise but the resources required to build a large-scale search engine are excessive. In this paper we propose to study the performance by building a scaled-down version of a search engine using virtualization tools to create a realistic distributed system. Scaling-down a distributed IR system will maintain the behaviour of the whole system and, at the same time, the computer requirements will be softened. This allows the use of virtualization tools to build a large-scale distributed system using just a small cluster of computers.