vNVMe on Hyper-V to unlock PCIe 5.0 NVMe performance
On hosts with NVMe PCIe 5.0 (E3.S/U.2), Hyper-V guests still use virtual SCSI and leave a lot of performance on the table. We are paying for top-tier storage, yet software becomes the limiter. A virtual NVMe device that preserves checkpoints/Replica/Live Migration would align guest performance with modern hardware without forcing DDA and its operational trade-offs.
Windows Server on ARM64 (Insider Previews)
When will there be a preview build of Windows Server on ARM? There is demand for it from developers, and devops personal as well. It is known that it already partial exists due to the article on Azure Host OS. Azure Host OS – Cloud Host - Microsoft Community Hub Please release this so we can test it against our code.b26085 - Windows Server 2025 Domain Controller fail to deploy via DSC
Hi there, I am trying to deploy mslab using Windows Server 2025 preview VM using Windows Server 2025 OS as a Hyper-V platform. I believe Jaromir as maintainer of mslab opened an SR. In result he updated the code, plus PS DSC Modules. edit: this issue is unrelated to the running SR. Still the deployment of the domain controller template will fail during first boot. This is not specific to b26085, this one is troubling for since WS2025 insider, so it never worked with this branch. Repro steps Install Windows Server 2025 b26085.1 on a physical machine and enable Hyper-V Download and extract mslab https://github.com/microsoft/MSLab/releases/tag/v24.04.1 run the mslab scripts in order 1_Prereq 2_CreateParentDisks > select Windows Server 2025 ISO b26085 (WS 2022 ISO will work) > skip the MSU dialogue Domain Controller VM gets created from parent disk image First boot will fail with following error Creating DC VM Applying Unattend and copying Powershell DSC Modules PSPath : Microsoft.PowerShell.Core\FileSystem::J:\mslab_v24.04.1\Temp\MountDir PSParentPath : Microsoft.PowerShell.Core\FileSystem::J:\mslab_v24.04.1\Temp PSChildName : MountDir PSDrive : J PSProvider : Microsoft.PowerShell.Core\FileSystem PSIsContainer : True Name : MountDir FullName : J:\mslab_v24.04.1\Temp\MountDir Parent : Temp Exists : True Root : J:\ Extension : CreationTime : 21.04.2024 13:20:16 CreationTimeUtc : 21.04.2024 11:20:16 LastAccessTime : 21.04.2024 13:20:16 LastAccessTimeUtc : 21.04.2024 11:20:16 LastWriteTime : 21.04.2024 13:20:16 LastWriteTimeUtc : 21.04.2024 11:20:16 Attributes : Directory Mode : d----- BaseName : MountDir Target : {} LinkType : Path : J:\mslab_v24.04.1\Temp\MountDir Online : False Path : J:\mslab_v24.04.1\Temp\MountDir Online : False PSPath : Microsoft.PowerShell.Core\FileSystem::J:\mslab_v24.04.1\Temp\MountDir\Windows\Panther PSParentPath : Microsoft.PowerShell.Core\FileSystem::J:\mslab_v24.04.1\Temp\MountDir\Windows PSChildName : Panther PSDrive : J PSProvider : Microsoft.PowerShell.Core\FileSystem PSIsContainer : True Name : Panther FullName : J:\mslab_v24.04.1\Temp\MountDir\Windows\Panther Parent : Windows Exists : True Root : J:\ Extension : CreationTime : 21.04.2024 13:20:22 CreationTimeUtc : 21.04.2024 11:20:22 LastAccessTime : 21.04.2024 13:20:22 LastAccessTimeUtc : 21.04.2024 11:20:22 LastWriteTime : 21.04.2024 13:20:22 LastWriteTimeUtc : 21.04.2024 11:20:22 Attributes : Directory Mode : d----- BaseName : Panther Target : {J:\Windows\Panther} LinkType : Creating DSC Configs for DC LastWriteTime : 21.04.2024 13:20:23 Length : 1206 Name : DC.meta.mof LastWriteTime : 21.04.2024 13:20:25 Length : 32600 Name : DC.mof Copying DSC configurations (pending.mof and metaconfig.mof) Applying changes to VHD LogPath : C:\WINDOWS\Logs\DISM\dism.log ScratchDirectory : LogLevel : WarningsInfo Starting DC Configuring DC using DSC takes a while. Initial configuration in progress. Sleeping 250 seconds Question: What could be reasons it keeps failing? We have no clue / pointers and imho it would be expected and necessary that mslab works with WS2025, despite being preview, too. Who at Microsoft could afford time to repro and looking into that? As mslab is also used by Microsoft, I hope anyone could spare time to investigate (with Jaromir and/or me). I personally can spare time for that investigation. Thank you very much in advance!Nested-V Dedup corruption 26100.1742 and Insider 26296.5001 (and Server 2022) is still there.
Nested-V, host can be Server 2019, Server 2022, Windows 10, Windows 11. Can be Intel or AMD. SSD recommended, 32 GB minimum. 1st level guest is Server 2022, 2025 or the newest vNext, dedup on drive D : active where the nested VMs reside. And they experience data corruption, and in some rare cases even on the D : drive of the 1st level guest. Does not happen if 1st level guest is Server 2019, rock solid then. (I have to use D : with a space, because that over-eagerness of office products to force auto-guess and auto-correct things crept into this forum too, converting it to a smiley!) The video, in that case Server 2022 on Win11 as host: https://www.joumxyzptlk.de/tmp/microsoft/S2022-Nested_Deduplication_VDI-Hyperv_profile_kills_filesystem_v2.mp4 See here my previous posts: https://techcommunity.microsoft.com/t5/windows-server-insiders/server-vnext-26040-and-server-2022-deduplication-data-corruption/m-p/4047321 Here: https://techcommunity.microsoft.com/t5/windows-server-insiders/server-2025-hyper-v-deduplication-corruption-is-still-there/m-p/4136286 Here: https://techcommunity.microsoft.com/t5/windows-server-insiders/26063-deduplication-data-corruption-is-still-there/m-p/4067827 Still perfectly reproducible, in this case the host was just upgraded to Win11 24h2. What is new and different? I know you (i.e. Microsoft) not only does have a bug entry, it got reproduced, and in one case I even know the CPU type to be an E5-1650 where this bug got reproduced (though with ~50% chance there since that CPU is old and slow). I even know it got sorted into "existing features fixed" category this bug belongs since deduplication is not a new feature. Here the two screens from todays re-test: Happy fixing! I am lucky I never used deduplication on a CSV in a Hyper-V Cluster - I was just about to do in 2023, but then this happened. kind regards, Joachim Otahal
Issues restoring Windows 2025 domain controllers from snapshots
Build 26280.ge_prerelease.240824-1650 I am running the Windows 2025 domain controllers deployed on Hyper-V virtual machines. Hyper-V is installed on Standard D16s v3 Azure virtual machine. Scenario 1 When I create a Azure VM snapshot and then deploy a new Azure VM from that snapshot, the Windows 2025 Hyper-V based domain controllers won't boot (there is a back screen with infinite loading spinner). Scenario 2 - A Hyper-V checkpoint is created for Hyper-V based domain - The domain controller is restored from the checkpoint - The domain controller is backed up using Windows Server backup - The domain controller is restored to a new Hyper-V VM from Windows server backup - After the recovery, it won't boot with same back screen with infinite loading spinner as in Scenario 1 Both scenarios work well in all previous Windows versions.Windows Server 2025 an Nanoserver
Hello everyone, Windows Server 2025 is already heading in the right direction. Especially in the production environment where you still have to be completely self-sufficient without a connection to the cloud. The only thing missing is that you can install Windows Nanoserver 2025 again as a VM with local domain connection for ASP.NET and services with .NET8. Greetings Michael
Hyper-V Application Issues
So I have moved a client from an old HP server to a new HP Gen 11 server running Server 2022 and Hyper-V. Everything is patched and running the newest firmware releases from HP> In the VM running server 2022 there is an application that runs very slowly when moved to the new hardware. We can not find the cause of the issue, but once moved back it runs fine. A new VM was created to run the application and it was the same. Everything else is fine and running as expected. If anyone can suggest what the cause could be?
Hyper-V on server 26227.5000 with VM on Hyper-V - VM only starts when disabling secure boot
Hi everyone, installed server 26227.500o on Hardware dl360 gen9 - as a test-system - runs smoothly. But a VM freshly installed crashes immediately after reboot. All tested with/without tpm, only with disabled secure boot vms is running and booting properly. Any tipps / thoughts
