Upload a VHD to Azure or copy a managed disk to another region - Azure CLI

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Applies to: ✔️ Linux VMs ✔️ Windows VMs ✔️ Flexible scale sets

This article explains how to either upload a VHD from your local machine to an Azure managed disk or copy a managed disk to another region, using AzCopy. This process, direct upload, enables you to upload a VHD up to 32 TiB in size directly into a managed disk. Currently, direct upload is supported for Ultra Disks, Premium SSD v2, Premium SSD, Standard SSD, and Standard HDD.

If you're providing a backup solution for IaaS VMs in Azure, you should use direct upload to restore customer backups to managed disks. When uploading a VHD from a source external to Azure, speeds depend on your local bandwidth. When uploading or copying from an Azure VM, your bandwidth would be the same as standard HDDs.

Secure uploads with Microsoft Entra ID

If you're using Microsoft Entra ID to control resource access, you can now use it to restrict uploading of Azure managed disks. This feature is available as a GA offering in all regions. When a user attempts to upload a disk, Azure validates the identity of the requesting user in Microsoft Entra ID, and confirms that user has the required permissions. At a higher level, a system administrator could set a policy at the Azure account or subscription level, to ensure that a Microsoft Entra identity has the necessary permissions for uploading before allowing a disk or a disk snapshot to be uploaded. If you have any questions on securing uploads with Microsoft Entra ID, reach out to this email: azuredisks@microsoft .com

Prerequisites

Restrictions

  • VHDs can't be uploaded to empty snapshots.
  • Azure Backup doesn't currently support disks secured with Microsoft Entra ID.
  • Azure Site Recovery doesn't currently support disks secured with Microsoft Entra ID.

Assign RBAC role

To access managed disks secured with Microsoft Entra ID, the requesting user must have either the Data Operator for Managed Disks role, or a custom role with the following permissions:

  • Microsoft.Compute/disks/download/action
  • Microsoft.Compute/disks/upload/action
  • Microsoft.Compute/snapshots/download/action
  • Microsoft.Compute/snapshots/upload/action

For detailed steps on assigning a role, see Assign Azure roles using Azure CLI. To create or update a custom role, see Create or update Azure custom roles using Azure CLI.

Get started

If you'd prefer to upload disks through a GUI, you can do so using Azure Storage Explorer. For details refer to: Use Azure Storage Explorer to manage Azure managed disks

Prerequisites

To upload your VHD to Azure, you need to create an empty managed disk that is configured for this upload process. Before you create one, there's some additional information you should know about these disks.

This kind of managed disk has two unique states:

  • ReadToUpload, which means the disk is ready to receive an upload but, no secure access signature (SAS) has been generated.
  • ActiveUpload, which means that the disk is ready to receive an upload and the SAS has been generated.

Note

While in either of these states, the managed disk will be billed at standard HDD pricing, regardless of the actual type of disk. For example, a P10 will be billed as an S10. This will be true until revoke-access is called on the managed disk, which is required in order to attach the disk to a VM.

Create an empty managed disk

Before you can create an empty standard HDD for uploading, you need the file size of the VHD you want to upload, in bytes. To get that, you can use either wc -c <yourFileName>.vhd or ls -al <yourFileName>.vhd. This value is used when specifying the --upload-size-bytes parameter.

Create an empty standard HDD for uploading by specifying both the -–for-upload parameter and the --upload-size-bytes parameter in a disk create cmdlet:

Replace <yourdiskname>, <yourresourcegroupname>, <yourregion> with values of your choosing. The --upload-size-bytes parameter contains an example value of 34359738880, replace it with a value appropriate for you.

Important

If you're creating an OS disk, add --hyper-v-generation <yourGeneration> to az disk create.

If you're using Microsoft Entra ID to secure disk uploads, add -dataAccessAuthmode 'AzureActiveDirectory'. When uploading to an Ultra Disk or Premium SSD v2 you need to select the correct sector size of the target disk. If you're using a VHDX file with a 4k logical sector size, the target disk must be set to 4k. If you're using a VHD file with a 512 logical sector size, the target disk must be set to 512.

VHDX files with logical sector size of 512k aren't supported.

##For Ultra Disk or Premium SSD v2, add --logical-sector-size and specify either 512 or 4096, depending on if you're using a VHD or VHDX

az disk create -n <yourdiskname> -g <yourresourcegroupname> -l <yourregion> --os-type Linux --for-upload --upload-size-bytes 34359738880 --sku standard_lrs

If you would like to upload a different disk type, replace standard_lrs with premium_lrs, premium_zrs, standardssd_lrs, standardssd_zrs, premiumv2_lrs, or ultrassd_lrs.

(Optional) Grant access to the disk

If you're using Microsoft Entra ID to secure uploads, you need to assign RBAC permissions to grant access to the disk and generate a writeable SAS.

az role assignment create --assignee "{assignee}" \
--role "{Data Operator for Managed Disks}" \
--scope "/subscriptions/{subscriptionId}/resourcegroups/{resourceGroupName}/providers/{providerName}/{resourceType}/{resourceSubType}/{diskName}"

Generate writeable SAS

Now that you've created an empty managed disk that is configured for the upload process, you can upload a VHD to it. To upload a VHD to the disk, you need a writeable SAS, so that you can reference it as the destination for your upload.

Important

On February 15th, 2025, the Shared Access Signature (SAS) access time for disks and snapshots will be limited to a maximum of 60 days. Trying to generate a SAS with an expiration longer than 60 days results in an error. Any existing disk or snapshot SAS created with an expiration longer than 60 days may stop working 60 days after the date of creation and will result in a 403 error during authorization.

If a managed disk or snapshot SAS's expiration is longer than 60 days, revoke its access, and generate a new SAS that requests access for 60 days (5,184,000 seconds) or less. Improve your overall security by using SAS with shorter expiration dates. Make these changes before February 15, 2025 to prevent service interruption. The following links can be used to find, revoke, and request a new SAS.

To generate a writable SAS of your empty managed disk, replace <yourdiskname> and <yourresourcegroupname>, then use the following command:

az disk grant-access -n <yourdiskname> -g <yourresourcegroupname> --access-level Write --duration-in-seconds 86400

Sample returned value:

{
  "accessSas": "https://md-impexp-t0rdsfgsdfg4.blob.core.windows.net/w2c3mj0ksfgl/abcd?sv=2017-04-17&sr=b&si=600a9281-d39e-4cc3-91d2-923c4a696537&sig=xXaT6mFgf139ycT87CADyFxb%2BnPXBElYirYRlbnJZbs%3D"
}

Upload a VHD or VHDX

Now that you have a SAS for your empty managed disk, you can use it to set your managed disk as the destination for your upload command.

Use AzCopy v10 to upload your local VHD or VHDX file to a managed disk by specifying the SAS URI you generated.

This upload has the same throughput as the equivalent standard HDD. For example, if you have a size that equates to S4, you'll have a throughput of up to 60 MiB/s. But, if you have a size that equates to S70, you'll have a throughput of up to 500 MiB/s.

AzCopy.exe copy "c:\somewhere\mydisk.vhd" "sas-URI" --blob-type PageBlob

After the upload is complete, and you no longer need to write any more data to the disk, revoke the SAS. Revoking the SAS changes the state of the managed disk and allow you to attach the disk to a VM.

Replace <yourdiskname>and <yourresourcegroupname>, then use the following command to make the disk usable:

az disk revoke-access -n <yourdiskname> -g <yourresourcegroupname>

Copy a managed disk

Direct upload also simplifies the process of copying a managed disk. You can either copy within the same region or cross-region (to another region).

The following script does this for you. The process is similar to the steps described earlier, with some differences since you're working with an existing disk.

Important

You need to add an offset of 512 when you're providing the disk size in bytes of a managed disk from Azure. This is because Azure omits the footer when returning the disk size. The copy will fail if you don't do this. The following script already does this for you.

Replace the <sourceResourceGroupHere>, <sourceDiskNameHere>, <targetDiskNameHere>, <targetResourceGroupHere>, and <yourTargetLocationHere> (an example of a location value would be uswest2) with your values, then run the following script in order to copy a managed disk.

Tip

If you are creating an OS disk, add --hyper-v-generation <yourGeneration> to az disk create.

sourceDiskName=<sourceDiskNameHere>
sourceRG=<sourceResourceGroupHere>
targetDiskName=<targetDiskNameHere>
targetRG=<targetResourceGroupHere>
targetLocation=<yourTargetLocationHere>
#Expected value for OS is either "Windows" or "Linux"
targetOS=<yourOSTypeHere>

sourceDiskSizeBytes=$(az disk show -g $sourceRG -n $sourceDiskName --query '[diskSizeBytes]' -o tsv)

az disk create -g $targetRG -n $targetDiskName -l $targetLocation --os-type $targetOS --for-upload --upload-size-bytes $(($sourceDiskSizeBytes+512)) --sku standard_lrs

targetSASURI=$(az disk grant-access -n $targetDiskName -g $targetRG  --access-level Write --duration-in-seconds 86400 --query [accessSas] -o tsv)

sourceSASURI=$(az disk grant-access -n $sourceDiskName -g $sourceRG --duration-in-seconds 86400 --query [accessSas] -o tsv)

azcopy copy $sourceSASURI $targetSASURI --blob-type PageBlob

az disk revoke-access -n $sourceDiskName -g $sourceRG

az disk revoke-access -n $targetDiskName -g $targetRG

Next steps

Now that you've successfully uploaded a VHD to a managed disk, you can attach the disk as a data disk to an existing VM or attach the disk to a VM as an OS disk, to create a new VM.

If you've more questions, see the uploading a managed disk section in the FAQ.