Virtual clusters

Because of the comparative inexpensiveness of hardware and the availability of open source software, cluster computing has become common for institutions with moderate to large needs for high performance computing. One of the problems with cluster computing, though, is that debugging existing or new system software or analyzing the effects of altering system hardware can require that a cluster be offline for extended periods of time. What is needed is a system for creating virtual clusters that can be used for experimentation. In this paper we present a free system for creating virtual clusters (or comparable systems of machines) that requires very little expertise on the part of the user. It facilitates short term experimentation with customized hardware configurations. An important advantage of our system is that it utilizes open source software such as QEMU by Bellard, F., VDE, TUN/TAP by Kraznyanski, M., Python, and Debian GNU/Linux to build virtual clusters. Another advantage of this system is that a user can easily set up a virtual cluster without having extensive knowledge of or experience with the aforementioned packages. Once the supporting framework has been established, the user merely writes a simple specification of the cluster and then deploys it. The specification language is an extension to XML which we call VCML (Virtual Cluster Markup Language). The specification is then "executed" by a system creation program which parses the spec and performs the operations necessary to deploy the virtual cluster.