Complete Multipart Upload

The Complete Multipart Upload operation completes a multipart upload of an object by assembling the previously uploaded parts.

Resolving conflicts

Conflicting client requests, such as two clients writing to the same key, are resolved on a "latest-wins" basis. The timing for the "latest-wins" evaluation is based on when the StorageGRID system completes a given request, and not on when S3 clients begin an operation.

Object size

StorageGRID supports objects up to 5 TB in size.

Note: The maximum size for objects that can be replicated to a destination bucket by the CloudMirror replication service is 625 GiB (671,088,640,000 bytes). Objects that match the filtering criteria in the CloudMirror replication configuration XML will not be ingested if they are larger than this size.

Request headers

The x-amz-storage-class request header is supported, and affects how many object copies StorageGRID creates if the matching ILM rule specifies an Ingest Behavior of Dual commit or Balanced.

Attention: If a multipart upload is not completed within 15 days, the operation is marked as inactive and all associated data is deleted from the system.
Note: The ETag value returned is not an MD5 sum of the data, but follows the Amazon S3 API implementation of the ETag value for multipart objects.


This operation completes a multipart upload. If versioning is enabled for a bucket, the object version is created upon completion of the multipart upload.

If versioning is enabled for a bucket, a unique versionId is automatically generated for the version of the object being stored. This versionId is also returned in the response using the x-amz-version-id response header.

If versioning is suspended, the object version is stored with a null versionId and if a null version already exists it will be overwritten.

Note: When versioning is enabled for a bucket, completing a multipart upload always creates a new version, even if there are concurrent multipart uploads completed on the same object key. When versioning is not enabled for a bucket, it is possible to initiate a multipart upload and then have another multipart upload initiate and complete first on the same object key. On non-versioned buckets, the multipart upload that completes last takes precedence.

Failed replication, notification, or metadata notification

If the bucket where the multipart upload occurs is configured for a platform service, multipart upload succeeds even if the associated replication or notification action fails.

If this occurs, an alarm is raised in the Grid Manager on Total Events (SMTT). The Last Event message displays "Failed to publish notifications for bucket-name object key" for the last object whose notification failed. (To see this message, select Nodes > Storage Node > Events. View Last Event at the top of the table.) Event messages are also listed in /var/local/log/bycasterr.log.

A tenant can trigger the failed replication or notification by updating the object's metadata or tags. A tenant can resubmit the existing values to avoid making unwanted changes.