How to use the command 'slurmctld' (with examples)

The ‘slurmctld’ command is a part of the Slurm workload manager and is responsible for monitoring all other Slurm daemons and resources, accepting work (jobs), and allocating resources to those jobs. It provides several options to manage and configure the slurmctld daemon.

Use case 1: Clear all previous slurmctld states from its last checkpoint

Code:

slurmctld -c

Motivation: Clearing all previous states from the last checkpoint of slurmctld can be useful when starting with a clean slate. It ensures that any residual or incorrect information from previous executions is removed, providing a fresh start.

Explanation: The ‘-c’ option instructs the slurmctld daemon to clear all previous states from its last checkpoint. It resets the state of the daemon and all associated resources.

Example output:

Slurmctld state has been cleared.

Use case 2: Set the daemon’s nice value to the specified value

Code:

slurmctld -n value

Motivation: Changing the daemon’s nice value can influence its priority and resource usage. By setting a lower nice value (typically a negative number), the slurmctld daemon can be given higher priority over other processes, ensuring that it gets the required resources in a timely manner.

Explanation: The ‘-n’ option followed by a value allows you to set the daemon’s nice value. The value is typically a negative number. The lower the value, the higher the priority of the slurmctld daemon.

Example output:

Slurmctld daemon's nice value has been set to -10.

Use case 3: Write log messages to the specified file

Code:

slurmctld -L path/to/output_file

Motivation: Writing log messages to a specific file can help in centralized log monitoring and analysis. It allows for easy tracking and troubleshooting of issues related to the slurmctld daemon without the need to search through large logs.

Explanation: The ‘-L’ option followed by the path to the output file enables the slurmctld daemon to write log messages to the specified file. The command will create the file if it does not already exist.

Example output:

Log messages are being written to the file: /var/log/slurmctld.log

Use case 4: Display help

Code:

slurmctld -h

Motivation: Sometimes we need a quick reference or reminder about the available options and arguments of a command. Using the ‘-h’ option with the slurmctld command displays a help message, providing information on how to use the command and its available options.

Explanation: The ‘-h’ option displays a help message explaining the usage of the slurmctld command and its available options.

Example output:

Usage: slurmctld [options]
Options:
  -c, --clear-state             Clear all previous slurmctld states from the last checkpoint
  -n, --nice=value              Set the daemon's nice value to the specified value
  -L, --log-file=path           Write log messages to the specified file
  -h, --help                    Display this help message
  -V, --version                 Display version information

Use case 5: Display version

Code:

slurmctld -V

Motivation: Sometimes it becomes necessary to check the version of a command or utility, especially when troubleshooting or comparing versions between different systems. The ‘-V’ option with the slurmctld command displays the version information.

Explanation: The ‘-V’ option displays the version information of the slurmctld command.

Example output:

Slurmctld version 20.11.0

Conclusion:

The ‘slurmctld’ command provides several options to manage and monitor the slurmctld daemon and associated resources. Whether it’s clearing states, adjusting the daemon’s nice value, writing log messages to a specified file, displaying help, or getting the version information, the ‘slurmctld’ command offers flexibility and control over the behavior of the slurmctld daemon.