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Object Storage Service:How do I upload a large object in parallel?

Last Updated:Mar 20, 2026

OSS supports two approaches for parallel large-object uploads: the ossutil CLI and the Multipart Upload API.

ossutil

Use the cp command with the following options to control concurrency and part size:

OptionDescription
-bigfile-thresholdSize threshold above which ossutil switches to multipart upload
-jobsNumber of concurrent file-level transfer tasks
-parallelNumber of concurrent part-level transfer tasks per file

For full parameter details and examples, see ossutil cp.

Multipart Upload API and SDK

Call the Multipart Upload API concurrently from your own code, or use the built-in concurrency controls in the OSS SDK:

SDKConcurrency parameterReference
Java SDKtaskNumResumable upload
Python SDKnum_threadsResumable upload

For other languages, call the Multipart Upload API directly and manage concurrency in your application code.

Applies to

  • Object Storage Service (OSS)