OpenPBS can easily be enabled on a CycleCloud cluster by modifying the "run_list" in the configuration section of your cluster definition. The two basic components of a PBS Professional cluster are the 'master' node which provides a shared filesystem on which the PBS Professional software runs, and the 'execute' nodes which are the hosts that mount the shared filesystem and execute the jobs submitted. For example, a simple cluster template snippet may look like:

[cluster my-pbspro]

[[node master]]
    ImageName = cycle.image.centos7
    MachineType = Standard_A4 # 8 cores

    run_list = role[pbspro_master_role]

[[nodearray execute]]
    ImageName = cycle.image.centos7
    MachineType = Standard_A1  # 1 core

    run_list = role[pbspro_execute_role]

Importing and starting a cluster with definition in CycleCloud will yield a single 'master' node. Execute nodes can be added to the cluster via the cyclecloud add_node command. For example, to add 10 more execute nodes:

cyclecloud add_node my-pbspro -t execute -c 10

PBS Resource-based Autoscaling

Cyclecloud maintains two resources to expand the dynamic provisioning capability. These resources are nodearray and machinetype.

If you submit a job and specify a nodearray resource by qsub -l nodearray=highmem -- /bin/hostname then CycleCloud will add nodes to the nodearray named 'highmem'. If there is no such nodearray then the job will remain idle.

Similarly if a machinetype resource is specified which a job submission, e.g. qsub -l machinetype:Standard_L32s_v2, then CycleCloud autoscales the 'Standard_L32s_v2' in the 'execute' (default) nodearray. If that machine type is not available in the 'execute' node array then the job will remain idle.

These resources can be used in combination as:

qsub -l nodes=8:ppn=16:nodearray=hpc:machinetype=Standard_HB60rs

which will autoscale only if the 'Standard_HB60rs' machines are specified an the 'hpc' node array.

Adding additional queues assigned to nodearrays

On clusters with multiple nodearrays, it's common to create separate queues to automatically route jobs to the appropriate VM type. In this example, we'll assume the following "gpu" nodearray has been defined in your cluster template:

    [[nodearray gpu]]
    Extends = execute
    MachineType = Standard_NC24rs

        pbspro.slot_type = gpu

After importing the cluster template and starting the cluster, the following commands can be ran on the server node to create the "gpu" queue:

/opt/pbs/bin/qmgr -c "create queue gpu"
/opt/pbs/bin/qmgr -c "set queue gpu queue_type = Execution"
/opt/pbs/bin/qmgr -c "set queue gpu resources_default.ungrouped = false"
/opt/pbs/bin/qmgr -c "set queue gpu = scatter"
/opt/pbs/bin/qmgr -c "set queue gpu resources_default.slot_type = gpu"
/opt/pbs/bin/qmgr -c "set queue gpu default_chunk.ungrouped = false"
/opt/pbs/bin/qmgr -c "set queue gpu default_chunk.slot_type = gpu"
/opt/pbs/bin/qmgr -c "set queue gpu enabled = true"
/opt/pbs/bin/qmgr -c "set queue gpu started = true"


The above queue definition will pack all VMs in the queue into a single VM scale set to support MPI jobs. To define the queue for serial jobs and allow multiple VM Scalesets, set ungrouped = true for both resources_default and default_chunk. You can also set = pack if you want the scheduler to pack jobs onto VMs instead of round-robin allocation of jobs. For more information on PBS job packing, see the official PBS Professional OSS documentation.

PBS Professional Configuration Reference

The following are the PBS Professional specific configuration options you can toggle to customize functionality:

PBS Pro Options Description
pbspro.slots The number of slots for a given node to report to PBS Pro. The number of slots is the number of concurrent jobs a node can execute, this value defaults to the number of CPUs on a given machine. You can override this value in cases where you don't run jobs based on CPU but on memory, GPUs, etc.
pbspro.slot_type The name of type of 'slot' a node provides. The default is 'execute'. When a job is tagged with the hard resource slot_type=<type>, that job will only run on a machine of the same slot type. This allows you to create different software and hardware configurations per node and ensure an appropriate job is always scheduled on the correct type of node.
pbspro.version Default: '18.1.3-0'. This is the PBS Professional version to install and run. This is currently the default and only option. In the future additional versions of the PBS Professional software may be supported.

Connect PBS with CycleCloud

CycleCloud manages OpenPBS clusters through an installable agent called azpbs. This agent connect to CycleCloud to read cluster and VM configurations and also integrates with OpenPBS to effectively process the job and host information. All azpbs configurations are found in the autoscale.json file, normally /opt/cycle/pbspro/autoscale.json.

  "password": "260D39rWX13X",
  "url": "",
  "username": "cyclecloud_api_user",
  "logging": {
    "config_file": "/opt/cycle/pbspro/logging.conf"
  "cluster_name": "mechanical_grid",

Important Files

The azpbs agent parses the PBS configuration each time it's called - jobs, queues, resources. Information is provided in the stderr and stdout of the command as well as to a log file, both at configurable levels. All PBS management commands (qcmd) with arguments are logged to file as well.

All these files can be found in the /opt/cycle/pbspro/ directory where the agent is installed.

File Location Description
Autoscale Config autoscale.json Configuration for Autoscale, Resource Map, CycleCloud access information
Autoscale Log autoscale.log Agent main thread logging including CycleCloud host management
Demand Log demand.log Detailed log for resource matching
qcmd Trace Log qcmd.log Logging the agent qcmd calls
Logging Config logging.conf Configurations for logging masks and file locations

Defining OpenPBS Resources

This project allows for a generally association of OpenPBS resources with Azure VM resources via the cyclecloud-pbspro (azpbs) project. This resource relationship defined in autoscale.json.

The default resources defined with the cluster template we ship with are

{"default_resources": [
      "select": {},
      "name": "ncpus",
      "value": "node.vcpu_count"
      "select": {},
      "name": "group_id",
      "value": "node.placement_group"
      "select": {},
      "name": "host",
      "value": "node.hostname"
      "select": {},
      "name": "mem",
      "value": "node.memory"
      "select": {},
      "name": "vm_size",
      "value": "node.vm_size"
      "select": {},
      "name": "disk",
      "value": "size::20g"

The OpenPBS resource named mem is equated to a node attribute named node.memory, which is the total memory of any virtual machine. This configuration allows azpbs to process a resource request such as -l mem=4gb by comparing the value of the job resource requirements to node resources.

Note that disk is currently hardcoded to size::20g. Here is an example of handling VM Size specific disk size

      "select": {"node.vm_size": "Standard_F2"},
      "name": "disk",
      "value": "size::20g"
      "select": {"node.vm_size": "Standard_H44rs"},
      "name": "disk",
      "value": "size::2t"

Autoscale and Scalesets

CycleCloud treats spanning and serial jobs differently in OpenPBS clusters. Spanning jobs will land on nodes that are part of the same placement group. The placement group has a particular platform meaning (VirtualMachineScaleSet with SinglePlacementGroup=true) and CC will managed a named placement group for each spanned node set. Use the PBS resource group_id for this placement group name.

The hpc queue appends the equivalent of -l place=scatter:group=group_id by using native queue defaults.

Installing the CycleCloud OpenPBS Agent azpbs

The OpenPBS CycleCloud cluster will manage the installation and configuration of the agent on the server node. The preparation includes setting PBS resources, queues, and hooks. A scripted install can be done outside of CycleCloud as well.

# Prerequisite: python3, 3.6 or newer, must be installed and in the PATH
tar xzf cyclecloud-pbspro-pkg-2.0.5.tar.gz
cd cyclecloud-pbspro

# Optional, but recommended. Adds relevant resources and enables strict placement

# Optional. Sets up workq as a colocated, MPI focused queue and creates htcq for non-MPI workloads.

# Creates the azpbs autoscaler
./  --venv /opt/cycle/pbspro/venv

# Otherwise insert your username, password, url, and cluster name here.
./ --install-dir /opt/cycle/pbspro \
                             --username user \
                             --password password \
                             --url https://fqdn:port \
                             --cluster-name cluster_name

azpbs validate

CycleCloud supports a standard set of autostop attributes across schedulers:

Attribute Description
cyclecloud.cluster.autoscale.stop_enabled Is autostop enabled on this node? [true/false]
cyclecloud.cluster.autoscale.idle_time_after_jobs The amount of time (in seconds) for a node to sit idle after completing jobs before it is scaled down.
cyclecloud.cluster.autoscale.idle_time_before_jobs The amount of time (in seconds) for a node to sit idle before completing jobs before it is scaled down.


CycleCloud does not support the bursting configuration with Open PBS.


Even though Windows is an officially supported Open PBS platform, CycleCloud does not support running Open PBS on Windows at this time.