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GetObject

Contributors netapp-lhalbert netapp-madkat
PDFs

You can use the S3 GetObject request to retrieve an object from an S3 bucket.

GetObject and multipart objects

You can use the partNumber request parameter to retrieve a specific part of a multipart or segmented object. The x-amz-mp-parts-count response element indicates how many parts the object has.

You can set partNumber to 1 for both segmented/multipart objects and non-segmented/non-multipart objects; however, the x-amz-mp-parts-count response element is only returned for segmented or multipart objects.

UTF-8 characters in user metadata

StorageGRID does not parse or interpret escaped UTF-8 characters in user-defined metadata. GET requests for an object with escaped UTF-8 characters in user-defined metadata don't return the x-amz-missing-meta header if the key name or value includes unprintable characters.

Unsupported request header

The following request header is not supported and returns XNotImplemented:

  • x-amz-website-redirect-location

Versioning

If a versionId subresource is not specified, the operation fetches the most recent version of the object in a versioned bucket. If the current version of the object is a delete marker, a "Not Found" status is returned with the x-amz-delete-marker response header set to true.

Request headers for server-side encryption with customer-provided encryption keys (SSE-C)

Use all three of the headers if the object is encrypted with a unique key that you provided.

  • x-amz-server-side-encryption-customer-algorithm: Specify AES256.

  • x-amz-server-side-encryption-customer-key: Specify your encryption key for the object.

  • x-amz-server-side-encryption-customer-key-MD5: Specify the MD5 digest of the object's encryption key.

Caution The encryption keys you provide are never stored. If you lose an encryption key, you lose the corresponding object. Before using customer-provided keys to secure object data, review the considerations in Use server-side encryption.

Behavior of GetObject for Cloud Storage Pool objects

If an object has been stored in a Cloud Storage Pool, the behavior of a GetObject request depends on the state of the object. See HeadObject for more details.

Note If an object is stored in a Cloud Storage Pool and one or more copies of the object also exist on the grid, GetObject requests will attempt to retrieve data from the grid, before retrieving it from the Cloud Storage Pool.
State of object Behavior of GetObject

Object ingested into StorageGRID but not yet evaluated by ILM, or object stored in a traditional storage pool or using erasure coding

200 OK

A copy of the object is retrieved.

Object in Cloud Storage Pool but not yet transitioned to a non-retrievable state

200 OK

A copy of the object is retrieved.

Object transitioned to a non-retrievable state

403 Forbidden, InvalidObjectState

Use a RestoreObject request to restore the object to a retrievable state.

Object in process of being restored from a non-retrievable state

403 Forbidden, InvalidObjectState

Wait for the RestoreObject request to complete.

Object fully restored to the Cloud Storage Pool

200 OK

A copy of the object is retrieved.

Multipart or segmented objects in a Cloud Storage Pool

If you uploaded a multipart object or if StorageGRID split a large object into segments, StorageGRID determines whether the object is available in the Cloud Storage Pool by sampling a subset of the object's parts or segments. In some cases, a GetObject request might incorrectly return 200 OK when some parts of the object have already been transitioned to a non-retrievable state or when some parts of the object have not yet been restored.

In these cases:

  • The GetObject request might return some data but stop midway through the transfer.

  • A subsequent GetObject request might return 403 Forbidden.

GetObject and cross-grid replication

If you are using grid federation and cross-grid replication is enabled for a bucket, the S3 client can verify an object's replication status by issuing a GetObject request. The response includes the StorageGRID-specific x-ntap-sg-cgr-replication-status response header, which will have one of the following values:

Grid Replication status

Source

  • SUCCESS: The replication was successful.

  • PENDING: The object hasn't been replicated yet.

  • FAILURE: The replication failed with a permanent failure. A user must resolve the error.

Destination

REPLICA: The object was replicated from the source grid.
Note StorageGRID does not support the x-amz-replication-status header.