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Automatically grow and shrink the HPC Pack cluster resources in Azure according to the cluster workload

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If you deploy Azure "burst" nodes (Both windows and Linux) in your HPC Pack cluster, or you create an HPC Pack cluster in Azure VMs, you may want a way to automatically grow or shrink the cluster resources such as nodes or cores according to the workload on the cluster. Scaling the cluster resources in this way allows you to use your Azure resources more efficiently and control their costs.

With HPC Pack 2016 or later version you can automatically grow and shrink HPC Pack compute nodes that are running azure cloud, including windows PaaS nodes, Azure IaaS VM nodes, Azure batch pool nodes, and Azure VM Scale Set nodes. But for different type of nodes, the auto grow shrink logic is different. And here is the summary:

Node Type how to enable prerequisite how to monitor
Azure PaaS nodes PowerShell cmdlet
Set-HpcClusterProperty -EnableGrowShrink 1		 1. Node template for Azure PaaS Nodes
2. Nodes added in the cluster		 "Auto grow shrink report" under ClusterManager --> Resource management --> Operations --> AzureOperations
Azure IaaS nodes PowerShell cmdlet
Set-HpcClusterProperty -EnableGrowShrink 1		 1. Azure Service Principal configured
2. Nodes added in the cluster		 "Auto grow shrink report" under ClusterManager --> Resource management --> Operations --> AzureOperations
Azure VM Scale Set nodes PowerShell cmdlet
Set-HpcClusterProperty -EnableGrowShrink 1		 1. Azure Service Principal configured
2. Nodes added in the cluster		 "Auto grow shrink report" under ClusterManager --> Resource management --> Operations --> AzureOperations
Azure Batch pool Azure Batch pool node template Azure Batch pool need to be started azure portal or azure batch explorer

Note

This feature just automatically grows or shrinks the Azure resources by starting or stopping the existing HPC compute nodes in Azure, it will not automatically create new HPC compute nodes or delete existing nodes.

The auto scaling of Azure VM scale set nodes is supported from HPC Pack 2016 Update 2 onwards.

Auto scaling of Azure IaaS VM nodes or Azure VM scale set nodes

To automatically grow or shrink the Azure IaaS VM nodes or Azure VM scale set nodes in HPC Pack cluster, you shall configure an Azure Service Principal with certificate to manage your Azure subscription. You can configure it with PowerShell commands or with Cluster Manager GUI.

After the Azure Service Principal is configured, you can enable auto grow shrink using HPC Pack AutoGrowShrink cmdlet.

Note

By default, the Azure Service Principal created by HPC Pack is granted the Contributor role at the Subscription level, you can refer to Access control for Azure resources in HPC Pack cluster to manually re-configure the access permissions for the Azure Service Principal according to your user scenario.

Configure Azure Service Principal with powershell

  1. After cluster deployment, connect by Remote Desktop to one head node.

  2. Upload the certificate (PFX format with private key) to each head node and install to Cert:\LocalMachine\My. This certificate is used to create azure service principal. If you don't have a cert, you can create a self-signed one first.

  3. Start Azure PowerShell as an administrator and run the following commands on one head node:

    cd $env:CCP_HOME\bin

Connect-AzureRmAccount

    If your account is in more than one Azure Active Directory tenant or Azure subscription, you can run the following command to select the correct tenant and subscription:

    Connect-AzureRmAccount -TenantId <TenantId> -SubscriptionId <subscriptionId>

    Run the following command to view the currently selected tenant and subscription:

    Get-AzureRMContext

  4. Run the following script

    .\ConfigARMAutoGrowShrinkCert.ps1 -DisplayName "YourHpcPackAppName" -HomePage "https://YourHpcPackAppHomePage" -IdentifierUri "https://YourHpcPackAppUri" -CertificateThumbprint "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" -TenantId xxxxxxxx-xxxxx-xxxxx-xxxxx-xxxxxxxxxxxx

    where

    DisplayName - Azure Active Application display name. If the application does not exist, it is created in Azure Active Directory.

    HomePage - The home page of the application. You can configure a dummy URL, as in the preceding example.

    IdentifierUri - Identifier of the application. You can configure a dummy URL, as in the preceding example.

    CertificateThumbprint - Thumbprint of the certificate you installed on the head node in Step 2.

    TenantId - Tenant ID of your Azure Active Directory. You can get the Tenant ID from the Azure Active Directory portal Properties page.

    For more details about ConfigARMAutoGrowShrinkCert.ps1, run Get-Help .\ConfigARMAutoGrowShrinkCert.ps1 -Detailed.

  5. After configuration, you could check the registry key setting (including ApplicationId, TenantId, Thumbprint) through HPC Powershell command

    Get-HpcClusterRegistry

Configure Azure Service principal with Cluster Manager GUI

  1. Open HPC Pack Cluster Manager on one head node.

  2. Goto Configuration --> Deployment To-do List page.

  3. Click Set Azure Deployment Configuration.

  4. Going through this wizard, it will help you configure Azure Service Principal, the Azure Resource Group and VNet where you azure VM will be provisioned as well as a certificate to be used for cluster communication. The wizard will run as below:

    Azure Deploy Setting Wizard

Validating the configuration

After you successfully configured the azure Service Principal, you shall be able to start and stop Azure IaaS VM nodes through HPC Pack.

If you are running HPC Pack 2016 Update 2 or later version, Azure IaaS VM nodes or Azure VM scale set nodes should be already in AzureIaaSNodes node group, you can perform Start or Stop action against them from the HPC Cluster Manager GUI. When the action is performed, you will see Dispatch Stop Azure VM Operation or Starting Azure Virtual Machines operation under the Operations --> AzureOperations view.

If you have VMs that are manually installed with HPC Pack Update 1 or earlier version on the azure, by default, they are not in the AzureIaaSNodes node group as they are being treated as on-premises node. In this case, you need to perform Stop action against them which will make the service to put them into AzureIaaSNodes node group and then the service is able to grow and shrink them.

If you don't have any Azure IaaS VM node yet, you can follow Adding IaaS nodes to create Azure IaaS node template and add IaaS VM nodes into the cluster.

Auto scaling of Azure PaaS nodes

Before you enable auto grow shrink Azure Windows PaaS nodes by HPC Pack Cluster, you shall check your azure node template making sure that the azure PaaS nodes are configured to start and stop manually instead of time schedule based.

HPC Pack auto grow shrink service will never add new resource to the cluster. Thus in any case after you create the azure PaaS node template, you need to add the nodes into the cluster first by:

  1. Launch HPC Cluster Manager, go to Resource management Pane
  2. Click Add Node... action from the action pane, from the wizard, choose "Add Windows Azure nodes"
  3. Going through the wizard, Click Finish, a number of nodes will be added into the cluster in Not-Deployed state
  4. Enable auto grow shrink using HPC Pack AutoGrowShrink cmdlet

Note

When HPC Pack grow resource for queued jobs, it will at most grow the number of nodes you added in step 3. It will never add more resource to the cluster. Thus you can check your subscription capacity and add appropriate number of nodes into the cluster.

Auto scaling of Azure Batch pool

By default when you creating an azure batch pool template in HPC Pack we have a default auto scale formula defined for the pool. But you can also refer to this doc to define your own scale formula and the update in your batch node template.

HPC PowerShell commands to set cluster auto grow and shrink property

Following are sample HPC PowerShell commands to set AutoGrowShrink and to tune its behavior with additional parameters. See AutoGrowShrink parameters later in this article for the complete list of settings.

To run these commands, start HPC PowerShell on the cluster head node as an administrator.

To view the AutoGrowShrink current setting

Get-HpcClusterProperty –AutoGrowShrink

To enable the AutoGrowShrink property

Set-HpcClusterProperty –EnableGrowShrink 1

To disable the AutoGrowShrink property

Set-HpcClusterProperty –EnableGrowShrink 0

To change the grow interval in minutes

Set-HpcClusterProperty –GrowInterval <interval>

To change the shrink interval in minutes

Set-HpcClusterProperty –ShrinkInterval <interval>

To view the current configuration of AutoGrowShrink

Get-HpcClusterProperty –AutoGrowShrink

To exclude node groups from AutoGrowShrink

Set-HpcClusterProperty –ExcludeNodeGroups <group1,group2,group3>

Note

This parameter is supported starting in HPC Pack 2016

AutoGrowShrink parameters

The following are AutoGrowShrink parameters that you can modify by using the Set-HpcClusterProperty command.

  • EnableGrowShrink - Switch to enable or disable the AutoGrowShrink property.

  • TasksPerResourceUnit - Number of tasks to grow one resource unit (based on job's resource unit type). The default is to grow one resource unit per task.

  • GrowThreshold - Threshold of jobs which have queued tasks to trigger automatic growth. The default is 1, which means that if there is 1 or more jobs which have queued tasks, automatically grow nodes.

  • GrowInterval - Interval in minutes to trigger automatic growth. The default interval is 5 minutes.

  • ShrinkInterval - Interval in minutes to trigger automatic shrinking. The default interval is 5 minutes.|

  • ShrinkIdleTimes - Number of continuous checks to shrink to indicate the nodes are idle. The default is 3 times. For example, if the ShrinkInterval is 5 minutes, HPC Pack checks whether the node is idle every 5 minutes. If the nodes are in the idle state for all the 3 continuous checks (15 minutes), then HPC Pack decides to shrink that node.

  • ExtraNodesGrowRatio - Additional percentage of nodes to grow for Message Passing Interface (MPI) jobs. The default value is 1, which means that HPC Pack grows nodes 1% for MPI jobs.

  • GrowByMin - Switch to indicate whether the autogrow policy is based on the minimum resources required for the job. The default is false, which means that HPC Pack grows nodes for jobs based on the maximum resources required for the jobs.

  • SoaJobGrowThreshold - Threshold of incoming SOA requests to trigger the automatic grow process. The default value is 50000.

    Note

    This parameter is supported starting in HPC Pack 2012 R2 Update 3.

  • SoaRequestsPerCore -Number of incoming SOA requests to grow one core. The default value is 20000.

    Note

    This parameter is supported starting in HPC Pack 2012 R2 Update 3.

  • ExcludeNodeGroups – Nodes in the specified node groups do not automatically grow and shrink.

    Note

    This parameter is supported starting in HPC Pack 2016.

MPI example

By default HPC Pack grows 1% extra nodes for MPI jobs (ExtraNodesGrowRatio is set to 1). The reason is that MPI may require multiple nodes, and the job can only run when all nodes are ready. When Azure starts nodes, occasionally one node might need more time to start than others, causing other nodes to be idle while waiting for that node to get ready. By growing extra nodes, HPC Pack reduces this resource waiting time, and potentially saves costs. To increase the percentage of extra nodes for MPI jobs (for example, to 10%), run a command similar to

Set-HpcClusterProperty -ExtraNodesGrowRatio 10

SOA example

By default, SoaJobGrowThreshold is set to 50000 and SoaRequestsPerCore is set to 20000. If you submit one SOA job with 70000 requests, there is one queued task and incoming requests are 70000. In this case HPC Pack grows 1 core for the queued task, and for incoming requests, grows (70000 - 50000)/20000 = 1 core, so in total grows 2 cores for this SOA job.