Slurm Cluster Management on

Slurm Cluster Lifecycle Management

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

A OneSlurm Cluster is a OneFlow service. You create, scale and delete it with the oneflow commands.

Task	Command
Create a Cluster	`oneflow-template instantiate 'Service OneSlurm'`
List Clusters	`oneflow list`
Show the VMs of a Cluster	`oneflow show <SERVICE_ID>`
Change the number of workers	`oneflow scale <SERVICE_ID> worker <NUMBER>`
Delete a Cluster	`oneflow delete <SERVICE_ID>`

The Quick Start Guide demonstrates how to create a Cluster.

Add Workers

oneflow scale <SERVICE_ID> worker 4

OneFlow creates the new worker VMs. Each new worker reads the Cluster data from OneGate and joins Slurm as a dynamic node, as described in Core Concepts. Check the new nodes from the controller.

Cluster Configuration

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The controller writes the Slurm configuration. The workers download it from the controller at start (configless mode), so they have no configuration files of their own.

Files on the Controller

File	Content
`/etc/slurm/slurm.conf`	Cluster, scheduler, plugins and partition
`/etc/slurm/gres.conf`	`AutoDetect=nvidia`, to find NVIDIA GPUs
`/etc/slurm/cgroup.conf`	`CgroupAutomount=yes` and `ConstrainDevices=yes`

Default `slurm.conf`

Setting	Value	Meaning
`ClusterName`	`one`	Name of the Slurm Cluster
`SlurmctldHost`	`slurm-one-controller`	Hostname of the controller
`AuthType`	`auth/munge`	Munge authentication
`SchedulerType`	`sched/backfill`	Backfill scheduling
`SelectType`	`select/cons_tres`	Allocates CPUs, memory and GPUs per job
`ProctrackType`	`proctrack/cgroup`	Tracks job processes with cgroups
`TaskPlugin`	`task/cgroup,task/affinity`	Limits tasks with cgroups and pins them to CPUs
`GresTypes`	`gpu`	GPUs as generic resources
`SlurmctldParameters`	`enable_configless`	Workers download the configuration
`MaxNodeCount`	`100`	Maximum number of dynamic nodes
`Nodeset`	`one Feature=one`	Groups all the workers
`PartitionName`	`all Nodes=ALL Default=yes`	One partition with all the nodes

With InfiniBand enabled, the controller also adds MpiDefault=pmix and PropagateResourceLimitsExcept=MEMLOCK. Refer to the InfiniBand Documentation.

Worker Profiles and Accelerators

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CPU, memory, disk and GPUs are settings of the worker VM template, not service inputs. Change the template before you create the service or before you add workers.

onetemplate update <WORKER_TEMPLATE_ID>

Each worker reports its CPUs, memory and GPUs to Slurm when it joins, so Slurm always uses the real size of the VM.

CPU and Memory

The Marketplace worker template has 1 CPU and 1 GB of memory. Set values for CPU, VCPU and MEMORY in the template appropriately for your jobs. For CPU pinning and NUMA, refer to the documentation about NUMA and CPU Pinning.

Identity Management

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A user needs the same account, with the same UID and GID, on the controller and on every worker. OneSlurm gets these accounts from an LDAP directory, through SSSD on each VM.

Identity Modes

Choose one mode when you create the service.

Mode	Inputs	What the appliance does
Disabled (default)	Leave the LDAP inputs empty	No LDAP. SSSD is stopped. Only local Linux users exist
Local LDAP	`ONEAPP_LDAP_ENABLE=YES`	Installs OpenLDAP on the controller and connects the controller and the workers to it
External LDAP	`ONEAPP_LDAP_URL` and `ONEAPP_LDAP_DOMAIN`	Connects the controller and the workers to your LDAP server

With ONEAPP_LDAP_ENABLE=YES, the appliance ignores ONEAPP_LDAP_URL.

Shared Storage

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A job can run on any worker, so users need the same files on the controller and on every worker. OneSlurm can mount two NFS exports in every VM of the Cluster.

Parameter	Mount point	Example
`ONEAPP_SLURM_NFS_HOME`	`/home`	`10.125.0.1:/srv/nfs/slurm/home`
`ONEAPP_SLURM_NFS_SCRATCH`	`/scratch`	`10.125.0.1:/srv/nfs/slurm/scratch`

Both are optional. An empty value skips the mount.

Before You Start

The controller and worker images already include the NFS client.

InfiniBand and High-Performance Networking

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

OneSlurm can configure IPoIB on the workers and set Slurm for MPI jobs over InfiniBand. It is disabled by default.

Before You Start

Ensure that:

Each worker VM has an InfiniBand HCA, attached by PCI passthrough in the worker VM template. See PCI Passthrough.
The InfiniBand fabric already has a subnet manager. OneSlurm does not configure it.

What the Images Include

Image	Packages
Worker	`rdma-core`, `infiniband-diags`, UCX from the Canonical DOCA PPA, Open MPI runtime
Controller	Open MPI development packages, to compile MPI programs

Both images set the memlock limit to unlimited, which RDMA needs.

Monitoring and Troubleshooting

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Check the Cluster

Connect to the controller and use the Slurm commands on the command line:

onevm ssh <CONTROLLER_VM_ID>

Command	Shows
`sinfo`	Partitions and the state of each node
`scontrol show nodes`	CPUs, memory, GPUs and state of each node
`squeue`	Pending and running jobs
`onegate service show`	The VMs of the service, as OneGate sees them
`systemctl status slurmctld`	The Slurm controller daemon

On a worker, systemctl status slurmd shows the Slurm node daemon.

Slurm Cluster Management on

Slurm Cluster Lifecycle Management

Add Workers

Cluster Configuration

Files on the Controller

Default slurm.conf

Worker Profiles and Accelerators

CPU and Memory

Identity Management

Identity Modes

Shared Storage

Before You Start

InfiniBand and High-Performance Networking

Before You Start

What the Images Include

Monitoring and Troubleshooting

Check the Cluster

Default `slurm.conf`