Troubleshooting versioning

The following topics can help you troubleshoot some common Amazon S3 versioning issues.

I want to recover objects that were accidentally deleted in a versioning-enabled bucket

In general, when object versions are deleted from S3 buckets, there is no way for Amazon S3 to recover them. However, if you have enabled S3 Versioning on your S3 bucket, a DELETE request that doesn't specify a version ID cannot permanently delete an object. Instead, a delete marker is added as a placeholder. This delete marker becomes the current version of the object.

To verify whether your deleted objects are permanently deleted or temporarily deleted (with a delete marker in their place), do the following:

You can also verify a deleted object's status by using the HeadObject API operation from the AWS Command Line Interface (AWS CLI). To do so, use the following head-object command and replace the user input placeholders with your own information:

aws s3api head-object --bucket amzn-s3-demo-bucket --key index.html

If you run the head-object command on a versioned object whose current version is a delete marker, you will receive a 404 Not Found error. For example:

An error occurred (404) when calling the HeadObject operation: Not Found

If you run the head-object command on a versioned object and provide the object's version ID, Amazon S3 retrieves the object's metadata, confirming that the object still exists and is not permanently deleted.

aws s3api head-object --bucket amzn-s3-demo-bucket --key index.html --version-id versionID

{
"AcceptRanges": "bytes",
"ContentType": "text/html",
"LastModified": "Thu, 16 Apr 2015 18:19:14 GMT",
"ContentLength": 77,
"VersionId": "Zg5HyL7m.eZU9iM7AVlJkrqAiE.0UG4q",
"ETag": "\"30a6ec7e1a9ad79c203d05a589c8b400\"",
"Metadata": {}
}

If the object is found and the newest version is a delete marker, the previous version of the object still exists. Because the delete marker is the current version of the object, you can recover the object by deleting the delete marker.

After you permanently remove the delete marker, the second newest version of the object becomes the current version of the object, making your object available once again. For a visual depiction of how objects are recovered, see Removing delete markers.

To remove a specific version of an object, you must be the bucket owner. To delete a delete marker permanently, you must include its version ID in a DeleteObject request. To delete the delete marker, use the following command, and replace the user input placeholders with your own information:

aws s3api delete-object --bucket amzn-s3-demo-bucket --key index.html --version-id versionID

For more information about the delete-object command, see delete-object in the AWS CLI Command Reference. For more information about permanently deleting delete markers, see Managing delete markers.

I want to permanently delete versioned objects

In a versioning-enabled bucket, a DELETE request without a version ID cannot permanently delete an object. Instead, such a request inserts a delete marker.

To permanently delete versioned objects, you can choose from the following methods:

In a versioning-enabled bucket, a DELETE request that doesn't specify a version ID can remove only objects with a NULL version ID. If the object was uploaded when versioning was enabled, a DELETE request that doesn't specify a version ID creates a delete marker of that object.

I'm experiencing performance degradation after enabling bucket versioning

Performance degradation can occur on versioning-enabled buckets if there are too many delete markers or versioned objects, and if best practices aren't followed.

Too many delete markers

After you enable versioning on a bucket, a DELETE request without a version ID made to an object creates a delete marker with a unique version ID. Lifecycle configurations with an Expire current versions of objects rule add a delete marker with a unique version ID to every object. Excessive delete markers can reduce performance in the bucket.

When versioning is suspended on a bucket, Amazon S3 marks the version ID as NULL on newly created objects. An expiration action in a versioning-suspended bucket causes Amazon S3 to create a delete marker with NULL as the version ID. In a versioning-suspended bucket, a NULL delete marker is created for any delete request. These NULL delete markers are also called expired object delete markers when all object versions are deleted and only a single delete marker remains. If too many NULL delete markers accumulate, performance degradation in the bucket occurs.

Too many versioned objects

If a versioning-enabled bucket contains objects with millions of versions, an increase in 503 Service Unavailable errors can occur. If you notice a significant increase in the number of HTTP 503 Service Unavailable responses received for PUT or DELETE object requests to a versioning-enabled bucket, you might have one or more objects in the bucket with millions of versions. When you have objects with millions of versions, Amazon S3 automatically throttles requests to the bucket. Throttling requests protects your bucket from an excessive amount of request traffic, which could potentially impede other requests made to the same bucket.

To determine which objects have millions of versions, use S3 Inventory. S3 Inventory generates a report that provides a flat file list of the objects in a bucket. For more information, see Cataloging and analyzing your data with S3 Inventory.

To verify if there are high number of versioned objects in the bucket, use S3 Storage Lens metrics to view the Current version object count, Noncurrent version object count, and Delete marker object count. For more information about Storage Lens metrics, see Amazon S3 Storage Lens metrics glossary.

The Amazon S3 team encourages customers to investigate applications that repeatedly overwrite the same object, potentially creating millions of versions for that object, to determine whether the application is working as intended. For instance, an application overwriting the same object every minute for a week can create over ten thousand versions. We recommend storing less than one hundred thousand versions for each object. If you have a use case that requires millions of versions for one or more objects, contact the AWS Support team for assistance with determining a better solution.

Best practices

To prevent versioning-related performance degradation issues, we recommend that you employ the following best practices:

For additional Amazon S3 performance-optimization best practices, see Best practices design patterns.