# Confirm RDMA use before crediting a file transfer to SMB Direct

> Which capability and SMB setting should be checked before testing SMB Direct performance?

- Canonical URL: https://update.dsesecurity.com/updates/dse-20260908-143-confirm-rdma-use-before-crediting-a-file-transfer-to-smb-direct/
- Publisher: Detection Systems & Engineering (DSE Security)
- Author: DSE Security Editorial Team
- Published: 2026-09-08T18:14:48+00:00
- Modified: 2026-09-08T18:23:27+00:00
- Last reviewed by DSE: 2026-09-08
- Resource type: Guide
- DSE priority: Information
- Topics: IT, Networks & Infrastructure
- Reading time: 1 minutes

## What you need to know

Which capability and SMB setting should be checked before testing SMB Direct performance?

## Potentially affected

Administrators validating SMB Direct on RDMA-capable network paths.

## DSE recommendation

Have the storage and network owners agree on the intended RDMA path and representative test file.

## Article

## Source facts

SMB Direct uses network adapters with RDMA capabilities. SMB Multichannel discovers those capabilities and enables the Direct path. Without Multichannel, SMB uses the adapter’s ordinary TCP/IP path even if the hardware supports RDMA. Microsoft’s performance test begins by verifying RDMA support in PowerShell before measuring a large file transfer. [Microsoft documentation](https://learn.microsoft.com/en-us/windows-server/storage/file-server/smb-direct).

## Applicability

Identify both endpoints, their supported releases, adapter capabilities, drivers, network configuration, and SMB settings. Review the source requirements and any encryption-specific platform conditions before interpreting a throughput result.

## DSE recommendation

Have the storage and network owners agree on the intended RDMA path and representative test file. Record the current Multichannel and adapter state before testing. Define which measurements will distinguish the intended transport from a successful transfer over a different path.

## Verification

Inspect the active connection and adapter evidence during the controlled copy, then measure throughput and application behavior. Compare those observations with the approved RDMA design. Preserve a TCP-only result as a path-selection finding rather than reporting it as proof that SMB Direct is functioning.

## Official references

[Microsoft Learn: Improve performance of a file server with SMB Direct](https://learn.microsoft.com/en-us/windows-server/storage/file-server/smb-direct). Source reviewed September 8, 2026.

## Primary reference

- Name: Improve performance of a file server with SMB Direct
- Authority: Microsoft Learn
- URL: https://learn.microsoft.com/en-us/windows-server/storage/file-server/smb-direct
- Source publication date: Not stated by the source

## Citation and use

Preferred citation: “Confirm RDMA use before crediting a file transfer to SMB Direct,” DSE Security, https://update.dsesecurity.com/updates/dse-20260908-143-confirm-rdma-use-before-crediting-a-file-transfer-to-smb-direct/
Publishing principles: https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/
Usage and citation policy: https://update.dsesecurity.com/usage/
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