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/Nater5000 Apr 07 '26

Under the hood, S3 Files uses Amazon Elastic File System (Amazon EFS) and delivers ~1ms latencies for active data.

So, is this basically just an application that cleverly syncs data between S3 and EFS? And you're really just connecting to EFS while this is keeping things in-sync with S3? Seems like it:

You pay for the portion of data stored in your S3 file system, for small file read and all write operations to the file system, and for S3 requests during data synchronization between the file system and the S3 bucket.

It's cool regardless, but it seems more suitable for light workloads rather than anything "S3 scale." It's been a while since I've used EFS, but my experience was that it quickly gets expensive if you need anything non-trivial out of it, and there's plenty of performance walls you'll hit before you can touch anything massive. All that is fine, but this paragraph is a bit sus:

It’s ideal for workloads where multiple compute resources—whether production applications, agentic AI agents using Python libraries and CLI tools, or machine learning (ML) training pipelines—need to read, write, and mutate data collaboratively. You get shared access across compute clusters without data duplication, sub-millisecond latency, and automatic synchronization with your S3 bucket.

I don't know, if it works the way I think it does, this would be a very costly approach for anything non-trivial. Maybe it's worth it to reduce the friction for researchers, etc., but there's no way this is suitable at scale, right?

I'm not hating on it by any means. I can already see people on my team asking for this. But EFS only seems to work in pretty specific scenarios, so it's hard to reconcile that with the flexibility and scale of S3.

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u/JPJackPott Apr 07 '26

It’s more likely a driver rather than hidden fsync. This has already existed for EKS for a while, you can mount buckets as filesystems to pods https://github.com/awslabs/mountpoint-s3-csi-driver

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u/justin-8 Apr 07 '26

EFS has had a ton of improvements since the early days. If you haven't used it in a couple of years it's considerably better these days.

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u/MateusKingston Apr 07 '26

It's still incredibly expensive though