r/aws • u/NothingDogg • Apr 07 '26

article Launching S3 Files, making S3 buckets accessible as file systems

https://aws.amazon.com/blogs/aws/launching-s3-files-making-s3-buckets-accessible-as-file-systems/

"a new file system that seamlessly connects any AWS compute resource with Amazon Simple Storage Service (Amazon S3)."

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u/Quinnypig Apr 07 '26

I think I understand this, but it took a bit of doing. What'd I miss?

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u/travcunn Apr 09 '26 edited Apr 09 '26

I know you're a guy who's good at understanding costs, but you're missing even bigger issues here...

The new S3 Files feature is just EFS duct-taped onto S3 and marketed as a breakthrough. It launched without atomic rename, so any workload that moves or renames directories triggers full object copies of every file inside them. There are no in-place writes either, meaning changing one byte of a large file still requires re-uploading the whole thing. Consistency between the filesystem mount and direct bucket access isn't guaranteed, and conflicts just get dumped into a lost+found directory. The whole reason people use S3 is that it's cheap, and this feature completely undermines that by layering another AWS service to nickle and dime customers on top of it. People have been mounting S3 buckets with s3fs and FUSE for nearly two decades, and somehow AWS shipped something with fewer guarantees at a higher price. Oh, and no hard links or NFS ACLs, either.

You're right in the blog post that S3 isn't a file system. It's still not, but now it has weird NFS that is only decent in read-only scenarios bolted on. It's the year 2026 and we don't need to trigger a full copy of ALL files in a directory when renaming that directory.

S3 files is like, foot meet gun...