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Unable to Build Switchless Storage using Network ATC
3-Node HV/S2D Cluster using Switchless Storage and Network ATC getting Network HUD Error
I have a Dell 3-node server cluster being used to host Hyper-V with S2D. Each node is identical and certified to pass S2D requirements. The networking consists of 2 onboard 1 Gbps and 2 quad-port PCI(e) NICs at 10/25 Gbps. The 2 onboard ports are being used for the management intent, 2 ports from each of those NICs are being connected to 2 top-of-rack switches for the compute intent at a total of 12 10 Gbps connections, and the other 2 ports from each of those NICs are being connected directly to the other nodes in a dual mesh method for the storage intent at a total of 6 25 Gbps connections. Very similar to the Microsoft diagram for a three-node storage switchless, dual TOR, dual link deployment network reference pattern for Azure Local, but I am using Windows Server 2025 Datacenter, not Azure Local.
The problem I am encountering is when I attempt to create the switchless storage intent, I get an error (shown below) that reads "Failed to fetch physical NIC mapping from the Network HUD service. Please diagnose..." If I leave off the switchless option, it builds without issue. The error only occurs when I attempt to use the switchless option.
I tried without configuring the NIC IP addresses first, as well as trying configuring the NIC IP addresses beforehand. I tried without having a cluster built first, as well as building a failover cluster without storage before running the network intent command. The error I posted below shows my last attempt after having the NICs configured with IP addresses and having a failover cluster established before running the command. The error has remained the same throughout the process.
Has anyone else run into an issue like this with switchless storage? It seems like everything that I am trying to do is within scope and should be a supported solution. My fallback plan is to use my existing switches, but that drops my connection speeds down from 25 Gbps to 10 Gbps due to hardware limitations.
2 Replies
This could be a possible cause. Trying to post this for informational purposes but it keeps getting blocked.
I would like to point out that I did also try some troubleshooting with AI and it thinks the following summary is the problem. Figured I would post this as well in case this is useful information to anyone online here. I tried to include it in my original post but I think this is what was causing my post to get blocked as SPAM.
The Windows Server 2025 NetworkATC PowerShell module calls Get-HUDSwitchlessMapping before submitting a switchless storage intent. Get-HUDSwitchlessMapping attempts to read HKLM:\Cluster\NetworkHUD\Mapping\<ClusterName>, but that registry path is never created on a healthy three-node Failover Cluster. As a result, ConvertFrom-Json receives $null, the wrapper catches the exception, and Add-NetIntent -Switchless always throws Failed to fetch physical NIC mapping from the Network HUD service.
