Start-AzureStorageBlobCopy vs AzCopy: which one takes lesser time

Question

I need to move vhds from one subscription to other. I would like to know which one is better option for the same: Start-AzureStorageBlobCopy or AzCopy?

Which one takes lesser time ?

Answer 1

Both of them would take the same time as all they do is initiate Async Server-Side Blob Copy. They just tell the service to start copying blob from source to destination. The actual copy operation is performed by Azure Blob Storage Service. The time it would take to copy the blob would depend on a number of factors including but not limited to:

• Source & destination location.
• Size of the source blob.
• Load on storage service.

Answer 2

Running AzCopy without specifying the option /SyncCopy and running PowerShell command Start-AzureStorageBlobCopy should take the same duration, because they both use server side asynchronous copy.

If you'd like to copy blobs across regions, you'd better consider specifying the option /SyncCopy while executing AzCopy in order to achieve a consistent speed because the asynchronous copying of data will run in the background of servers that being said you might see inconsistent copying speed among your “copying” operations.

If /SyncCopy option is specified, AzCopy will download the content to memory first, and then upload content back to Azure Storage. In order to achieve better performance of /SyncCopy, you are supposed to run AzCopy in the VM whose region is the same as source storage account. Besides that, the VM size (which decides bandwidth and CPU core number) will probably impact the copying performance as well.

For further information, please refer to Getting Started with the AzCopy Command-Line Utility