Get standby pool and instance details

A standby pool is a dynamic resource that stays in sync with your scale set as your workload scales up and down. This article discusses how to retrieve various information about your standby pool and the instances within it.

Standby pool details

Use the standby pool runtime view APIs to get the current status of your standby pool including how many instances are available, the provisioning state, and what zones are being utilized.

CLI

az standby-vm-pool status --resource-group myResourceGroup --name myStandbyPool

{
  "id": "/subscriptions/{subscriptionId}/resourceGroups/myResourceGroup/providers/Microsoft.StandbyPool/standbyVirtualMachinePools/myStandbyPool/runtimeViews/latest",
    {
      "zone": 1
    },
      "instanceCountsByState": [
        {
          "count": 5,
          "state": "Creating"
        },
        {
          "count": 0,
          "state": "Starting"
        },
        {
          "count": 5,
          "state": "Running"
        },
        {
          "count": 0,
          "state": "Deallocating"
        },
        {
          "count": 10,
          "state": "Deallocated"
        },
        {
          "count": 0,
          "state": "Deleting"
        }
      ],
      "zone": 2
    },
    {
      "instanceCountsByState": [
        {
          "count": 0,
          "state": "Creating"
        },
        {
          "count": 10,
          "state": "Starting"
        },
        {
          "count": 0,
          "state": "Running"
        },
        {
          "count": 5,
          "state": "Deallocating"
        },
        {
          "count": 5,
          "state": "Deallocated"
        },
        {
          "count": 0,
          "state": "Deleting"
        }
      ],
      "zone": 3
    },
    {
      "instanceCountsByState": [
        {
          "count": 0,
          "state": "Creating"
        },
        {
          "count": 0,
          "state": "Starting"
        },
        {
          "count": 5,
          "state": "Running"
        },
        {
          "count": 10,
          "state": "Deallocating"
        },
        {
          "count": 3,
          "state": "Deallocated"
        },
        {
          "count": 5,
          "state": "Deleting"
        }
      ],
  "name": "latest",
  "provisioningState": "Succeeded",
  "resourceGroup": "myResourceGroup",
  "type": "Microsoft.StandbyPool/standbyVirtualMachinePools/runtimeViews"
}

PowerShell

Get-AzStandbyVMPoolStatus -ResourceGroupName myResourceGroup -Name myStandbyPool

Id: /subscriptions/{subscriptionId}/resourceGroups/myResourceGroup/providers/Microsoft.StandbyPool/standbyVirtualMachinePools/mmyStandbyPool/runtimeViews/latest
InstanceCountSummary: {{
        {
        "zone": 1
        },
        "instanceCountsByState": [
        {
            "state": "Creating",
            "count": 0
        },
        {
            "state": "Starting",
            "count": 5
        },
        {
            "state": "Running",
            "count": 0
        },
        {
            "state": "Deallocating",
            "count": 10
        },
        {
            "state": "Deallocated",
            "count": 5
        },
        {
            "state": "Deleting",
            "count": 0
        }
        ],
        "zone": 2
        },
        {
        "instanceCountsByState": [
        {
            "state": "Creating",
            "count": 5
        },
        {
            "state": "Starting",
            "count": 0
        },
        {
            "state": "Running",
            "count": 5
        },
        {
            "state": "Deallocating",
            "count": 10
        },
        {
            "state": "Deallocated",
            "count": 0
        },
        {
            "state": "Deleting",
            "count": 0
        }
        ],
        "zone": 3
        },
        {
        "instanceCountsByState": [
        {
            "state": "Creating",
            "count": 0
        },
        {
            "state": "Starting",
            "count": 0
        },
        {
            "state": "Running",
            "count": 5
        },
        {
            "state": "Deallocating",
            "count": 10
        },
        {
            "state": "Deallocated",
            "count": 5
        },
        {
            "state": "Deleting",
            "count": 0
        }
        ]
     }
  }
Name                         : latest
ProvisioningState            : Succeeded
ResourceGroupName            : myResourceGroup
Type                         : Microsoft.StandbyPool/standbyVirtualMachinePools/runtimeViews

REST

GET https://management.azure.com/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.StandbyPool/standbyVirtualMachinePools/{standbyVirtualMachinePoolName}/runtimeViews/{runtimeView}?api-version=2024-03-01

{
  "properties": {
    "instanceCountSummary": [
      {
        "zone": 1,
        "instanceCountsByState": [
          {
            "state": "creating",
            "count": 5
          },
          {
            "state": "running",
            "count": 0
          },
          {
            "state": "deallocating",
            "count": 10
          },
          {
            "state": "deallocated",
            "count": 5
          },
          {
            "state": "starting",
            "count": 0
          },
          {
            "state": "deleting",
            "count": 0
          }
        ]
      },
      {
        "zone": 2,
        "instanceCountsByState": [
          {
            "state": "creating",
            "count": 0
          },
          {
            "state": "running",
            "count": 5
          },
          {
            "state": "deallocating",
            "count": 10
          },
          {
            "state": "deallocated",
            "count": 10
          },
          {
            "state": "starting",
            "count": 0
          },
          {
            "state": "deleting",
            "count": 0
          }
        ]
      },
      {
        "zone": 3,
        "instanceCountsByState": [
          {
            "state": "creating",
            "count": 0
          },
          {
            "state": "running",
            "count": 0
          },
          {
            "state": "deallocating",
            "count": 15
          },
          {
            "state": "deallocated",
            "count": 15
          },
          {
            "state": "starting",
            "count": 0
          },
          {
            "state": "deleting",
            "count": 0
          }
        ]
      }
    },
    "provisioningState": "Succeeded"
  },
  "id": "/subscriptions/{subscriptionId}/resourceGroups/myResourceGroup/providers/Microsoft.StandbyPool/standbyVirtualMachinePools/pool/runtimeViews/latest",
  "name": "myStandbyPool",
  "type": "Microsoft.StandbyPool/standbyVirtualMachinePools/runtimeViews",
  "systemData": {
    "createdBy": "pooluser@microsoft.com",
    "createdByType": "User",
    "createdAt": "2024-02-14T23:31:59.679Z",
    "lastModifiedBy": "pooluser@microsoft.com",
    "lastModifiedByType": "User",
    "lastModifiedAt": "2024-02-14T23:31:59.679Z"
  }

Instance details

When a virtual machine is in a standby pool, the isVmInStandbyPool parameter is set to true. When the virtual machine is moved from the pool instance the scale set, the parameter is automatically updated to false. This can be useful in determining when a virtual machine is ready to receive traffic or not.

CLI

az vm get-instance-view --resource-group myResourceGroup --name myVM

    "extensions": null,
    "hyperVGeneration": "V2",
    "isVmInStandbyPool": true,
    "maintenanceRedeployStatus": null,
    "statuses": [
      {
        "code": "ProvisioningState/succeeded",
        "displayStatus": "Provisioning succeeded",
        "level": "Info",
        "message": null,
        "time": "2024-08-02T17:22:46.295536+00:00"
      },
      {
        "code": "PowerState/deallocated",
        "displayStatus": "VM deallocated",
        "level": "Info",
        "message": null,
        "time": null
      }
    ],

PowerShell

Get-AzVM -ResourceGroupName myResourceGroup -Name myVM -Status


ResourceGroupName : myResourceGroup
Name              : myVM
HyperVGeneration  : V2
IsVMInStandbyPool : True
BootDiagnostics   : 
Disks[0]          : 
  Name            : myVM_1a995f8c_OsDisk_1_c250259c33b942eb910504cf6512332d
  Statuses[0]     : 
    Code          : ProvisioningState/succeeded
    Level         : Info
    DisplayStatus : Provisioning succeeded
    Time          : 10/4/2024 7:45:11 PM
Statuses[0]       : 
  Code            : ProvisioningState/succeeded
  Level           : Info
  DisplayStatus   : Provisioning succeeded
  Time            : 10/4/2024 7:45:11 PM
Statuses[1]       : 
  Code            : PowerState/deallocated
  Level           : Info
  DisplayStatus   : VM deallocated

REST

GET https://management.azure.com/subscriptions/{subscriptionId}/resourceGroups/myResourceGroup/providers/Microsoft.Compute/virtualMachines/myVM/instanceView?api-version=2024-07-01

{
  "bootDiagnostics": {},
  "isVMInStandbyPool": true,
  "hyperVGeneration": "V2",
  "statuses": [
    {
      "code": "ProvisioningState/succeeded",
      "level": "Info",
      "displayStatus": "Provisioning succeeded",
      "time": "2024-08-02T17:22:46.2955369+00:00"
    },
    {
      "code": "PowerState/deallocated",
      "level": "Info",
      "displayStatus": "VM deallocated"
    }
  ]
}

Next steps

Review the most frequently asked questions about standby pools for Virtual Machine Scale Sets.