Copying blobs in Azure Blob Storage can vary dramatically in speed depending on the technique used. Three approaches are compared: the naive download-and-re-upload (slowest, ~1 hour for 10GB), server-side copy via StartCopyFromUriAsync (good for same-account copies, effectively instantaneous), and parallel block-from-URL copy (fastest for cross-account copies, completing a 10GB transfer in ~9 seconds). Benchmarks across same-region, cross-region, and same-account scenarios are provided. The parallel approach mimics AzCopy by staging multiple blocks concurrently from a SAS URI, keeping data off your machine. Key caveats include handling resilience, copying metadata/tags/properties explicitly, and access tier considerations.
Table of contents
Download and re-upload (Avoid!)Server-side copy ( StartCopyFromUriAsync )Parallel block-from-URL copyCopying within the same storage accountExample timingsIs it an exact copy?Summary232 Impressions