From the DreamHost Status Blog:
On Tuesday, September 20th from 10am to 6pm, we will be upgrading Ceph, the underlying storage system of DreamObjects, to the “Jewel” release. The new release includes support for AWS signature version 4, features needed to enable static site hosting in the future, and fixes numerous bugs. We expect the upgrade process to last only a few hours but we are allowing for additional time for monitoring and tuning.
During the maintenance, DreamObjects could be temporarily unavailable. However, your data stored in DreamObjects will remain safe.
If you have any questions or concerns, please don’t hesitate to contact support for assistance.
Follow the progress on the maintenance on the DreamHost status blog.
Update: The upgrade to the Jewel release is complete but we have confirmed that there are issues accessing some old buckets. While the data in the buckets remain safely stored in the cluster, the public API servers are returning errors when attempting retrieval. If you receive a 404 when trying to access a bucket from a client, or an error message of "This bucket has been deleted externally" in the DreamHost control panel, then your bucket is affected. Our team is investigating possible solutions. Follow the DreamHost status blog for updates.