Copying a large blob between Windows Azure Storage Account and datacenters, will probably require a Shared Access Signature so that the destination Windows Azure Storage Account will be able to read from the source blob. Without proper authorization the source Windows Azure Storage Account will return a 404 NOT Found Http Status Code.
Once you have a Shared Access Signature, I strongly recommend using the StartCopyFromBlob method from the destination Block Blob reference. This method provides you with an ID that can be used to cancel the queued copy operation.
Then you can follow the operation’s progression through the CopyState property by pulling for an updated Block Blob reference by using the GetBlobReferenceFromServer method form the destination container.
Alexandre Brisebois ☁ 