Getting Started with OneSlurm on

Overview

Wed, 07 Oct 2026 00:00:00 +0000

Slurm is an open source workload manager and job scheduler for AI and HPC workloads on Linux Clusters. It gives jobs access to compute nodes, starts and monitors them, and keeps pending jobs in a queue.

OneSlurm deploys a Slurm Cluster on OpenNebula as a OneFlow service. The service has two roles:

Role	Appliance	What it does
`controller`	Service Slurm Controller	Runs `slurmctld`, schedules jobs and owns the Slurm configuration. Users log in here to submit jobs
`worker`	Service Slurm Worker	Runs `slurmd` and executes jobs. You can add or remove workers at any time

Both roles come together in the Service OneSlurm appliance of the OpenNebula Public Marketplace. The controller publishes the Cluster data through OneGate, and each worker reads it and joins the Cluster without manual steps.

Requirements and Preparation

Wed, 07 Oct 2026 00:00:00 +0000

Requirements

Requirement	Details
OpenNebula	7.0, 7.2 or 7.4
OneFlow	Running. OneSlurm is a OneFlow service
OneGate	Running and reachable from the controller and worker VMs
OneGate to OneFlow	OneGate can reach the OneFlow API
Virtual Network	One network for the service. The controller and the workers attach to it
Port 6817/TCP	Open from the workers to the controller, for `slurmctld` and configless Slurm

OneGate Details

The controller publishes the Cluster data through OneGate, and the workers read it. Without OneGate, no worker joins the Cluster.
The VMs can reach OneGate directly or through the transparent proxies.
OneGate must reach the active OneFlow server. The :oneflow_server: setting in /etc/one/onegate-server.conf sets it.

To check it, run this command in any VM of the service. It must print the service, not Service <id> not found.

Quick Start

Wed, 07 Oct 2026 00:00:00 +0000

This guide deploys a Slurm cluster with one controller and one worker, then runs a first job. You can create the service from Sunstone or from the CLI. Check the Requirements before proceeding.

Step 1: Import the Appliance

Export Service OneSlurm from the OpenNebula Public Marketplace. This creates the two images, the two VM templates and the OneFlow service template.

onemarketapp export 'Service OneSlurm' 'Service OneSlurm' --datastore default
IMAGE
 ID: 34
 ID: 35
VMTEMPLATE
 ID: 62
 ID: 63
SERVICE_TEMPLATE
 ID: 64

Step 2: Adjust the Templates (Optional)

The default parameters are enough for a test Cluster. For real workloads you may need more resources, for example, more CPUs or memory of the workers, or adding a GPU.

Core Concepts

Wed, 07 Oct 2026 00:00:00 +0000

Controller and Workers

	Controller	Worker
Slurm daemon	`slurmctld`	`slurmd`
Number of VMs	1	1 or more
Hostname	`slurm-one-controller`	The VM name, for example `worker-0--service-233`
Role in the Cluster	Schedules jobs, keeps the configuration, hosts the optional local LDAP	Runs jobs

Users connect to the controller to compile code and submit jobs with srun or sbatch.

Configless Slurm

The controller is the only VM that has the Slurm configuration files. The workers start slurmd with --conf-server slurm-one-controller:6817 and download the configuration from the controller. A change on the controller reaches every worker, and new workers need no configuration.