private byte[] DownloadBytes(string containerName, string blobName, long beginOffset, long endOffset, int parallelFactor=2)
{
var client = AzureHelper.GetCloudBlobClient();
var container = client.GetContainerReference(containerName);
var blobRef = container.GetBlockBlobReference(blobName);
var buffer = new byte[ endOffset - beginOffset +1];
blobRef.DownloadRangeToByteArray(buffer, 0, beginOffset, endOffset - beginOffset + 1, options: new BlobRequestOptions { ParallelOperationThreadCount = parallelFactor });
return buffer;
}