5.4 Node Availability Policies

Schedulers will allow jobs to be launched on a given compute node as long as the node is not full or busy. The parameter NODEAVAILABILITYPOLICY allows a site to determine what criteria constitutes a node being busy . The legal settings are listed in the table below:

The default setting for all nodes is COMBINED indicating that a node can accept workload so long as the jobs which the node was allocated to do not request or utilize more resources than the node has available. In a load balancing environment, this may not be the desired behavior. Setting the NODEAVAILABILITYPOLICY parameter to UTILIZED will allow jobs to be packed onto a node even if the aggregate resources requested exceeds the resources configured. For example, assume a scenario with a 4 processor compute node and 8 jobs requesting 1 processor each. If the resource availability policy was set to COMBINED , this node would only allow 4 jobs to start on this node even if the jobs induced a load of less than 1.0 each. With the resource availability policy set to UTILIZED, the scheduler would continue to allow jobs to be started on the node until the node's load average exceeded a per processor load value of 1.0 (in this case, a total load of 4.0). To prevent a node from being over populated within a single scheduling iteration, Maui will artificially raise the node's load for one scheduling iteration when starting a new job. On subsequent iterations, the actual measured node load information will be used.