This is interesting to me! I regularly deploy 25G network connections, but I don’t think we’d run SMB over that. I am super curious the industry and use case if you’re willing to share!
"SMB Direct" is RDMA based and ksmbd supports it. Samba does not. Disclaimer: I have not used it but was looking it up just yesterday.
I ran SMB over a 20gbit network (2x 10gbit). The use case was 3D rendering (photogrammetry specifically). There were multiple render nodes, and a central service coordinating the rendering process. The projects would be on SSD's on the central SMBD server, and after they were manually configured (using Agisoft Metashape) they'd be rendered. Projects would sometimes start as tens of gigabytes worth of photos, and the artifacts (including intermediates) would balloon into the hundreds of gigabytes, we'd have dozens of these projects per week.
I researched quite extensively prior to landing on SMB, but it really seems like there isn't a better way of doing this. The environment was mixed windows/linux, but if there was a better pure linux solution I would've pushed our office staff to switch to Ubuntu.