14 X.500 Performance with Large Databases and 0Sinet 1 P. V. Rajeev 2 S. V Raghavan 3 Department of Computer Science and Engineering Indian Institute of Technology, Madras, India rajeev %hss@lando.hns. com svr@iitm. ernet. in Ashok K. Agrawala Department of Computer Science, University of Maryland, College Park, MD USA. agrawala @cs. umd. edu Abstract The X.500 directory provides a powerful mechanism for storing and retrieving information about objects of interest in the networking world. The rapid increase in the deployment of the directory has resulted in a very large amount of data in the global directory. Hence, the need arises for the development of a model which predicts the performance of the directory in an internet environment with large amount of data. In this paper, we present a deterministic model for predicting the performance of X.500 directory operations. Actual measurements are carried out in a real life environment, with the directory having a large amount of data distributed across the internet. The model is validated by comparing the results of these actual measurements with the predicted values. The application of the model for the selection of DIT structure in a wide area network is explained. Keywords: X.500, Directory Services, Performance, Deterministic Modelling. 1 Network Software developed at Indian Institute of Technology, Madras. 2 Currently with Hughes Software Systems, New Delhi 3 Further correspondence may please be addressed to Dr. S.V. Raghavan. S. V. Raghavan et al. (eds.), Computer Networks, Architecture and Applications © Springer Science+Business Media Dordrecht 1995