Very little, I'm sure. S3 and Ceph were both introduced to the world in 2006, which means they had been in development at the same time - or perhaps S3 even a b

Very little, I'm sure. S3 and Ceph were both introduced to the world in 2006, which means they had been in development at the same time - or perhaps S3 even a bit before, since it was in a far more mature state by then. Also, while S3 and Ceph's RADOS both supposedly handle "objects" they're very different kinds of objects with very different APIs. And of course the metadata layers are completely different to serve different needs. It's practically certain that they both drew on the same common ancestors, but it's more likely that lessons learned from S3 informed subsequent development on Ceph than the other way around.