SMB Direct support in open-source Chimera-NAS

Chimera-NAS is a single LGPL library that implements NFS, SMB, and S3 server support over a single VFS with pluggable backend modules. The goal is to put fully user-space storage ecosystems on a level footing with the traditional kernel-side approach. While we’re at it, we can shed some of the historical API baggage that the traditional model must carry and gain more efficiency.

SMB has a reputation for being slower than NFS. I think for small-file or metadata intensive workloads, that’s probably fair. For streaming I/O, not necessarily so.

This is one Windows Server 2025 client with 2x200GbE served by one linux server with 4x200GbE using SMB3. SMB signing is disabled. No encryption. No compression. With SMB Direct we get pretty close to line rate. With multichannel TCP, about half line rate. The TCP results can be improved upon, I suspect, with work.

This is all still very much experimental software. Good for a demo but lots of work to do before it could be used in production. That’s why it’s open source, so you can help. 😉 An integration with any existing open source or commercial file system stack is possible, though an ideal fit would require a file system capable of running in user-space and possessing an asynchronous FS API.

Next time, I’ll share IO-per-second and FSOp-per-second results.

Source on GitHub

TCP Multi-Channel:

SMB Direct: