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Source facts

\n

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.

\n

Applicability

\n

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.

\n

DSE recommendation

\n

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.

\n

Verification

\n

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.

\n

Official references

\n

Microsoft Learn: Improve performance of a file server with SMB Direct. Source reviewed September 8, 2026.

", "content_text": "Source facts\nSMB 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.\nApplicability\nIdentify 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.\nDSE recommendation\nHave 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.\nVerification\nInspect 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.\nOfficial references\nMicrosoft Learn: Improve performance of a file server with SMB Direct. Source reviewed September 8, 2026.", "content_markdown": "## Source facts\n\nSMB 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).\n\n## Applicability\n\nIdentify 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.\n\n## DSE recommendation\n\nHave 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.\n\n## Verification\n\nInspect 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.\n\n## Official references\n\n[Microsoft Learn: Improve performance of a file server with SMB Direct](https://learn.microsoft.com/en-us/windows-server/storage/file-server/smb-direct). 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