How to archive big Azure managed disk to storage account as VHD file

Question

We have Azure VMs that we don't need anymore. But, we want to archive the data and os disks to low cost archive storage.

I used the script given in https://learn.microsoft.com/en-us/azure/virtual-machines/scripts/virtual-machines-powershell-sample-copy-managed-disks-vhd

#Provide the subscription Id of the subscription where managed disk is created
$subscriptionId = "yourSubscriptionId"

#Provide the name of your resource group where managed is created
$resourceGroupName ="yourResourceGroupName"

#Provide the managed disk name 
$diskName = "yourDiskName"

#Provide Shared Access Signature (SAS) expiry duration in seconds e.g. 3600.
#Know more about SAS here: https://docs.microsoft.com/en-us/Az.Storage/storage-dotnet-shared-access-signature-part-1
$sasExpiryDuration = "3600"

#Provide storage account name where you want to copy the underlying VHD of the managed disk. 
$storageAccountName = "yourstorageaccountName"

#Name of the storage container where the downloaded VHD will be stored
$storageContainerName = "yourstoragecontainername"

#Provide the key of the storage account where you want to copy the VHD of the managed disk. 
$storageAccountKey = 'yourStorageAccountKey'

#Provide the name of the destination VHD file to which the VHD of the managed disk will be copied.
$destinationVHDFileName = "yourvhdfilename"

#Set the value to 1 to use AzCopy tool to download the data. This is the recommended option for faster copy.
#Download AzCopy v10 from the link here: https://docs.microsoft.com/en-us/azure/storage/common/storage-use-azcopy-v10
#Ensure that AzCopy is downloaded in the same folder as this file
#If you set the value to 0 then Start-AzStorageBlobCopy will be used. Azure storage will asynchronously copy the data. 
$useAzCopy = 1 

# Set the context to the subscription Id where managed disk is created
Select-AzSubscription -SubscriptionId $SubscriptionId

#Generate the SAS for the managed disk 
$sas = Grant-AzDiskAccess -ResourceGroupName $ResourceGroupName -DiskName $diskName -DurationInSecond $sasExpiryDuration -Access Read 

#Create the context of the storage account where the underlying VHD of the managed disk will be copied
$destinationContext = New-AzStorageContext -StorageAccountName $storageAccountName -StorageAccountKey $storageAccountKey

#Copy the VHD of the managed disk to the storage account
if($useAzCopy -eq 1)
{
    $containerSASURI = New-AzStorageContainerSASToken -Context $destinationContext -ExpiryTime(get-date).AddSeconds($sasExpiryDuration) -FullUri -Name $storageContainerName -Permission rw
    azcopy copy $sas.AccessSAS $containerSASURI

}else{

    Start-AzStorageBlobCopy -AbsoluteUri $sas.AccessSAS -DestContainer $storageContainerName -DestContext $destinationContext -DestBlob $destinationVHDFileName
}

We have managed to copy VHD of the managed disk to a storage account. But, when it comes to copying the big disks up to 8 TB, the script fails with the following error

Response Details: <Code>InvalidHeaderValue</Code><Message>The value for one of the HTTP headers is not in the correct format. </Message><HeaderName>x-ms-blob-content-length</HeaderName><HeaderValue>8796093022720</HeaderValue>

But, I see that Page blobs have a maximum size of 8TB and Block blobs have a maximum size of 4.75TB. Hence, copying disks larger than 4.75 doesn't look practical.

Is there any alternative way to archive very big data disks into archive storage?

• tried to reduce the size of the disk, but is still big.