Deleting and copying files in Azure Blob Storage with PowerShell

In my previous post, I showed you how to upload and download files to and from Azure blob storage using the Azure PowerShell cmdlets. In this post, I’ll show you how to delete blobs, copy blobs, and start a long-term asynchronous copy of a large blob and then check the operation’s status until it’s finished. I’m going to continue with the container and blobs that I used in the previous post.

Setup

First, you need a storage account context. This is the same as in the previous post. To define a storage account context, you need the storage account name and key. Set the variables to storage account name and key. You can get these from the Storage Account in the Azure Portal.

$StorageAccountName = "yourStorageAccountName"
$StorageAccountKey = "yourStorageAccountKey"

Now let’s set up the storage account context.

$ctx = New-AzureStorageContext -StorageAccountName $StorageAccountName `
         -StorageAccountKey $StorageAccountKey

Now we need to set the name of the container that holds the blob(s ) that we want to delete. Set this to your container name.

$ContainerName = “images”

Delete a blob

To delete a blob, you need the storage context, container name, and blob name. So let’s set the blob name, and then use the PowerShell cmdlet to delete a blob.

$BlobName = “GuyEyeingOreos.png”

Remove-AzureStorageBlob -Blob $BlobName -Container $ContainerName -Context $ctx

Now get the list of blobs and you’ll see that the one you deleted is no longer there.

Get-AzureStorageBlob -Container $ContainerName -Context $ctx | Select Name

Copy a blob

Now let’s copy a blob to another blob with a different name. We’ll use the Start-AzureStorageBlobCopy cmdlet to do this. The copy is done asynchronously. If it’s a huge file, we can check the progress of the copy. I’ll show you how to do that after this. Here, I’m going to copy one of my blobs to another blob, then get a list so I can see if it worked.

Set the blob name of the source blob, then set the blob name of the target blob. Then do the copy.

$BlobName = "gizmodo_groundhog_texting.jpg"
$NewBlobName = "CopyOf_" + $BlobName

Start-AzureStorageBlobCopy -SrcBlob $BlobName -SrcContainer $ContainerName `
        -DestContainer $ContainerName -DestBlob $newBlobName -Context $ctx

Get-AzureStorageBlob -Container $ContainerName -Context $ctx | Select Name

You can see the new blob in the listing now.

Copy a blob asynchronously and check its progress

What if you have a really large blob, like a VHD file, and you want to copy it from one storage account to another? Maybe you even want to copy it to a storage account in another region, so you can recreate the VM in that region?

You may have noticed that there’s not a CopyBlob method per se – the cmdlet is Start-AzureCopyBlob. This is because the blob copy runs asynchronously. For small blobs, you don’t generally need to check the status of a copy operations – it will probably finish before you have a chance to check the status, depending on the size. For large blobs, though, like a VHD file that is 127 GB, it will take a while to copy it. So you want to be able to kick off the copy and then check the status later. Let’s see how to do that.

Setup the variables for the operation

I have a VHD file in the container “vhds” in one storage account and I’m going to copy it to a different storage account. Let’s start by setting the variables for the container name and blob name for the source. We will use the same blob name for the source and the destination.

$sourceContainer = "vhds"
$BlobName = "testasynccopysvc-testasynccopy-2015-06-16.vhd "

Next I’ll set up the name and key for the destination storage account. Fill these in with your own information.

$destStorageAccountName = "yourStorageAccountName"
$destStorageAccountKey = "yourStorageAccountKey"

We need a storage account context for the destination storage account.

$destctx = New-AzureStorageContext –StorageAccountName $destStorageAccountName `
        StorageAccountKey $destStorageAccountKey

Let’s set up the destination container. I’ll set the name and then create the container.

$destContainer = "copiedvhds"
New-AzureStorageContainer -name $destContainer -Context $destctx

Asynchronous copy and status check

Now let’s kick off the copy operation, then check the status by calling Get-AzureStorageBlobCopyState. You have to assign this to a variable representing the destination blob so you can check the status of the resulting blob. Notice that this copy command is a little bit different than the previous one – this one specifically provides the destination context because it’s different from the source context.

$BlobResult = Start-AzureStorageBlobCopy -SrcBlob $BlobName -SrcContainer $sourceContainer `
        -DestContainer $destContainer -DestBlob $BlobName -Context $ctx `
        -DestContext $destctx

$status = $BlobResult | Get-AzureStorageBlobCopyState
# show the status
$status

This shows that it is just starting the copy operation – the bytes copied is 0. Wait a few seconds and check the status again…

Now it shows the number of  bytes copied is greater than 0.

This PowerShell code will loop continuously until the status is not “Pending”. It will retrieve the status, display it, sleep 10 seconds, then loop around and check the status again. When the status no longer equals “Pending”, it will exit the loop.

While ($status.Status -eq "Pending") {
    $status = $BlobResult | Get-AzureStorageBlobCopyState
    $status
    Start-Sleep 10
}

When it’s completed, the final status will look like the following:

You can see that it has copied all the bytes, and the copy operation was successful.

Summary

In this post, we went over how to delete a blob and how to copy a blob to another blob. We also learned how to do an asynchronous copy of a large blob from one storage account to another, and check the status repeatedly until it was finished. In my next post, we will learn how to take a snapshot of a blob using PowerShell.

Tags: Async, Azure, Blob Storage, CopyBlob, DeleteBlob, PowerShell