Using and Administering

The negotiator Daemon

The negotiator daemon maintains status of each job and machine in the cluster and responds to queries from the llstatus and llq commands. The negotiator daemon runs on a single machine in the cluster (the central manager machine). This daemon is started, restarted, signalled, and stopped by the master daemon.

The negotiator daemon receives status messages from each schedd and startd daemon running in the cluster. The negotiator daemon tracks:

• Which schedd daemons are running
• Which startd daemons are running, and the status of each startd machine.

If the gsmonitor daemon does not send the negotiator an update about a machine within the time period defined by the MACHINE_UPDATE_INTERVAL keyword, then the negotiator assumes that the machine is down, and therefore the schedd and startd daemons are also down.

The negotiator also maintains in its memory several queues and tables which determine where the job should run.

The negotiator performs the following functions:

• Receives and records job status changes from the schedd daemon.
• Schedules jobs based on a variety of scheduling criteria and policy options. Once a job is selected, the negotiator contacts the schedd that originally created the job.
• Handles requests to:
  • Set priorities
  • Query about jobs
  • Remove a job
  • Hold or release a job
  • Favor or unfavor a user or a job.
• Receives notification of schedd resets indicating that a schedd has restarted.