Getting Started with Job Management Manager › Load Balancing › Scheduling Notes

Scheduling Notes

The following notes provide further information about scheduling load balancing and Load Balance Groups. These scenarios assume the manager is installed on all nodes in a cluster.

Default Behavior, Cluster

By default, load balancing is enabled for all systems in a cluster. If no Load Balance Group is specified for a job on a cluster, the job is scheduled to all nodes in a cluster.

Default behavior, standalone

By default, load balancing is disabled on non-clustered systems. Load Balance Group information for a job is ignored.

No Load Balance Group nodes available

When a job is scheduled to run but nodes are not available in the Load Balance Group, the job’s behavior is based on the setting of the logical NSCHED$LBAL$WAIT_AVAIL_NODE. If this system logical is TRUE, the job moves to the Job Slot Wait state until a node is available in the Load Balance Group. If this system logical is FALSE, the jobs run on the default node in the cluster.

Empty Load Balance Group

A Load Balance Group definition may be empty. In this case, all nodes in the cluster are Unselected, so the job does not run on any machine. If the system logical NSHCED$LBAL$WAIT_AVAIL_NODE is TRUE, the job moves to the Job Slot Wait state until a node is available in the Load Balance Group. If this system logical is FALSE, the jobs run on the default node in the cluster.

Deleted Load Balance Group

Deleting a Load Balance Group removes any reference to that group by a job definition. Those jobs begin to schedule to all nodes in the cluster. If you do not want this scheduling, do not delete a Load Balance Group as a first step. You can modify the jobs to assign them to another Load Balance Group or remove all nodes from the Load Balance Group. You can use the following command to help understand the impact of deleting the Load Balance Group:

   SCHEDULE SHOW JOB */LOAD_BALANCE_GROUP=group-name-to-be-deleted

This command shows you all jobs associated with the Load Balance Group.

Group specification override

The job cluster_node field, if not empty, overrides the group specification. This job runs on the specified node, regardless of the Load Balance group assigned to the job, whether the node is a member of that Load Balance group or not.

Batch and Remote Mode

A job defined with a mode of Batch or Remote is not eligible for Load Balancing. The selection of a load balance group in the Auxiliary Job Definition window is disabled. The Group Editor button remains active.