Enable on-demand bursting

Premium solid-state drives (SSD) have two available bursting models; credit-based bursting and on-demand bursting. This article covers how to switch to on-demand bursting. Disks that use the on-demand model can burst beyond their original provisioned targets. On-demand bursting occurs as often as needed by the workload, up to the maximum burst target. On-demand bursting incurs additional charges.

For details on disk bursting, see Managed disk bursting.

Important

You don't need to follow the steps in this article to use credit-based bursting. By default, credit-based bursting is enabled on all eligible disks.

Before you enable on-demand bursting, understand the following:

  • On-demand bursting cannot be enabled on a premium SSD that has less than 512 GiB. Premium SSDs less than 512 GiB will always use credit-based bursting.
  • On-demand bursting is only supported on premium SSDs. If a premium SSD with on-demand bursting enabled is switched to another disk type, then disk bursting is disabled.
  • On-demand bursting doesn't automatically disable itself when the performance tier is changed. If you want to change your performance tier but do not want to keep disk bursting, you must disable it.
  • On-demand bursting can only be enabled when the disk is detached from a VM or when the VM is stopped. On-demand bursting can be disabled 12 hours after it has been enabled.

Regional availability

Currently, the on-demand model for disk bursting is only available in West Central US.

Get started

On-demand bursting can be enabled with either the Azure PowerShell module, the Azure CLI, or Azure Resource Manager templates. The following examples cover how to create a new disk with on-demand bursting enabled and enabling on-demand bursting on existing disks.

On-demand bursting cmdlets are available in version 5.5.0 and newer of the Az module. Alternatively, you may use the Azure Cloud Shell.

Create an empty data disk with on-demand bursting

A managed disk must be larger than 512 GiB to enable on-demand bursting. Replace the <myResourceGroupDisk> and <myDataDisk> parameters then run the following script to create a premium SSD with on-demand bursting:

Set-AzContext -SubscriptionName <yourSubscriptionName>

$diskConfig = New-AzDiskConfig -Location 'WestCentralUS' -CreateOption Empty -DiskSizeGB 1024 -SkuName Premium_LRS -BurstingEnabled $true

$dataDisk = New-AzDisk -ResourceGroupName <myResourceGroupDisk> -DiskName <myDataDisk> -Disk $diskConfig

Enable on-demand bursting on an existing disk

A managed disk must be larger than 512 GiB to enable on-demand bursting. Replace the <myResourceGroupDisk>, <myDataDisk> parameters and run this command to enable on-demand bursting on an existing disk:

New-AzDiskUpdateConfig -BurstingEnabled $true | Update-AzDisk -ResourceGroupName <myResourceGroupDisk> -DiskName <myDataDisk> //Set the flag to $false to disable on-demand bursting

Next steps

To learn how to gain insight into your bursting resources, see Disk bursting metrics.