The virtual cluster: a dynamic network environment for exploitation of idle resources

Standard environments for exploiting idle time of workstations are based on some kind of spying process that detects low CPU usage and informs to a scheduler so that work can be dispatched. This approach generates local interference and, since the same local environment is used, could lead to security problems. We are investigating the exploitation of idle times in network resources based on a complete mode change in a candidate node. After the detection that some node is idle, a mode-switcher boots a new operating system that will work over a separate disk partition. After the boot phase the node is linked to a logical network topology and is available to receive jobs. Users can allocate nodes from this virtual cluster through a standard frontend as they would do in a "conventional" cluster. Because nodes may leave and join this virtual machine we use a distributed processor management to allow user applications to cope with this dynamic resource behavior. In this paper we describe the architecture of the virtual cluster and present the results obtained with a mode-switcher and a prototype application under real use conditions.