Copying one Azure blob to another blob in Azure Storage Client 2.0

Using Storage 6.3 (much newer library than in original question) and async methods use StartCopyAsync (MSDN)

  CloudStorageAccount storageAccount = CloudStorageAccount.Parse("Your Connection");

  CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();
  CloudBlobContainer container = blobClient.GetContainerReference("YourContainer");

  CloudBlockBlob source = container.GetBlockBlobReference("Your Blob");
  CloudBlockBlob target = container.GetBlockBlobReference("Your New Blob");
        
  await target.StartCopyAsync(source);

FYI as of the latest version (7.x) of the SDK this no longer works because the BeginStartCopyBlob function no longer exists.

You can do it this way:

// this tunnels the data via your program,
// so it reuploads the blob instead of copying it on service side
using (var stream = await sourceBlob.OpenReadAsync())
{
  await destinationBlob.UploadFromStreamAsync(stream);
}

As mentioned by @(Alexey Shcherbak) this is a better way to proceed:

await targetCloudBlob.StartCopyAsync(sourceCloudBlob.Uri);

while (targetCloudBlob.CopyState.Status == CopyStatus.Pending)
{
    await Task.Delay(500);
    // Need to fetch or "CopyState" will never update
    await targetCloudBlob.FetchAttributesAsync(); 
}

if (targetCloudBlob.CopyState.Status != CopyStatus.Success)
{
    throw new Exception("Copy failed: " + targetCloudBlob.CopyState.Status);
}

Gaurav Mantri has written a series of articles on Azure Storage on version 2.0. I have taken this code extract from his blog post of Storage Client Library 2.0 – Migrating Blob Storage Code for Blob Copy

CloudStorageAccount storageAccount = new CloudStorageAccount(new StorageCredentials(accountName, accountKey), true);
CloudBlobClient cloudBlobClient = storageAccount.CreateCloudBlobClient();
CloudBlobContainer sourceContainer = cloudBlobClient.GetContainerReference(containerName);
CloudBlobContainer targetContainer = cloudBlobClient.GetContainerReference(targetContainerName);
string blobName = "<Blob Name e.g. myblob.txt>";
CloudBlockBlob sourceBlob = sourceContainer.GetBlockBlobReference(blobName);
CloudBlockBlob targetBlob = targetContainer.GetBlockBlobReference(blobName);
targetBlob.StartCopyFromBlob(sourceBlob);