Deze lezing zal in het Nederlands worden gegegeven! This presentation will be in Dutch! In this talk we present our experiences with three closely coupled Linux clusters. This configuration was developed by SARA in close coorperation with the University of Amsterdam and recently became operational. The complete configuration consists of 120 nodes and a file server and is connected by a two layer network of a Gigabit Ethernet backbone and a dual switched Fast Ethernet connection to the nodes. In addition to sharing the fileserver and network, the clusters share the same NIS domain. Administratively the clusters are divided into netgroups. We will explain how and why we chose this configuration, including the chosen network solution. Additionally the installation process and the tools (e.g. NIS and CFEngine) used to maintain scalability and limit the costs of user administration and other operational aspects will be described. Furthermore we would like to look at the clusters from the user's point of view: What does a cluster mean for them and how is it different from the environment they were used to (i.e. either a stand-alone PC or the IBM RS6000/SP parallel computer). The batch system and message passing libraries like PVM and MPI, as well as available third party software will also be discussed.

Willem Vermin studied chemistry and crystallography at the University of Leiden. The subject of his thesis is 'het gebruik Karle-Hauptman matrices bij het oplossen van kleine kristalstructuren'. Since 1981 he is with SARA (the academic computing centre in Amsterdam). His function at this moment is senior consultant with parallel computing as specialism.