Ephemeral disk usage

So I have a particular use case using EKS on AWS. data is being streamed to a container, files of varied sizes from s3 that are scanned by ClamAV running on a container. will K8s cache that files that are larger than available RAM to ephemeral disk? is it possible to prevent that caching? Is it possible to prevent any container from using ephemeral storage?

Any help is appriciated!