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Microsoft changes the way it certifies network cards for Windows Server

Increased ‘configuration not supported’ heartbreak sparks move

Microsoft’s networking team has made a change to the way certifies network interface cards (NICs) for use in Windows Server.

As explained by team member Dan Cuomo, since the time of Windows Server 2008 Microsoft has certified NICs “based on adapter link speed which meant that any adapter of 10Gbps or higher had additional (Microsoft test) requirements imposed on it regardless of the adapter’s intended use (as designed by the manufacturer).”

That approach meant some NIC vendors would test for speed, not real-world performance. Yet servers are now asked to do all sorts of I/O intensive stuff like drive Microsoft’s own Storage Spaces Direct software-defined storage product that is increasingly used in hyperconverged infrastructure.

Raw speed is no indicator of how a NIC will work in a server that’s essentially being asked to take on the role of a shared storage array, Microsoft argues. Microsoft's old certifications therefore left customers unaware of scenarios a NIC might struggle to handle.

Microsoft became aware that its approach of assuming a faster NIC is a better NIC was inappropriate after Windows Server 2022 debuted.

Cuomo said the OS’ arrival saw “An increasing number of support cases which resulted in the frustrating support claim, ‘not supported’ despite the device having been certified.”

Microsoft’s response is a NIC certification regime that assesses performance based on whether a device can work in three roles:

  • Compute traffic: Traffic originating from or destined to a virtual machine (VM).
  • Storage traffic: Traffic using Server Message Block (SMB), for example, Storage Spaces Direct or SMB-based live migration.
  • Management traffic: Traffic to or from outside the local cluster. For example, storage replica traffic or that used by the administrator for management of the cluster like Remote Desktop, Windows Admin Center, Active Directory, etc.

The new certification regime does not match NICs to Microsoft products or applications.

“This change is intended to end the perilous phrase, ‘I’m sorry, but your configuration is not supported.’” Cuomo wrote. “We’ve heard your feedback on how frustrating it can be to call into support with a certified device only to find out that the adapter cannot be supported in the way that you’re using it.”

Not every NIC will be certified to meet one of Microsoft’s roles. In that case, Cuomo said it may still be fine to support an application that has a different traffic profile. ®

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