With the recent announcement that Hyper-V is strategic to Microsoft, as the main focus of Server 2025 you can imagine I've spent more time on the topic than usual lately. I normally don’t post on here, but I figured I'd share.
To get the basic stuff out of the way, yes you can Instantly Recovery ‘any’ workload to Hyper-V, and it can be automated with PowerShell - it will probably make it easier at scale. And for those new to Hyper-V with Veeam, on-host backup processing is the way to go. Did you know we recently updated the user guide to explain how Veeam selects VM generation upon arrival?
Veeam supports Azure Stack HCI too, and it has been on a much faster release cadence, so a lot of the features may have been seen before - but I think the key take away is that, there is significant forward motion for Hyper-V, and a continued path to purchasing perpetual licenses for it.
I wish that central management of Hyper-V was addressed a bit differently. For Hyper-V you can still choose between System Center VMM (SCVMM), Windows Admin Center (WAC), PowerShell, and classic Microsoft Management Console tools (MMC) - with of course Azure Arc VM support as well. This is the more obvious future - with Windows Admin Center making it into Azure too.
(When connecting Veeam to Hyper-V, connect the cluster correctly, it’s much easier than connecting via SCVMM, even if you’re using SCVMM to manage it.)
New Hyper-V focused features
- GPU partitioning (GPU-P) to allow assignment to VMs, with functional live migration of VMs between standalone servers. As well as GPU pools allowing HA of VMs using Discrete Device Assignment (DDA) between hosts.
- Dynamic Processor Compatibility - Allowing you mix CPU generations and get the best feature set that they all still support.
- Certificate-based clusters allowing you to create 'Workgroup Clusters' that do not depend on AD.
- Cluster-aware updating reliability and performance improvements.
- S2D stretched cluster support.
- Hyper-V Gen 2 VMs are the default, Azure Marketplace images will be Gen 2.
- Network ATC simplifying network configuration allowing you to specify intent (storage, network, compute), and Network HUD has some stabilization features, can quarantine an adapter when instability occurs or showing physical misconfigurations due to PCI resource sharing.
- SND multi-site allows L2 or L3 connectivity across physical locations for virtualized workloads and Kubernetes (Hybrid AKS). SDN gateway performance improved 20-50%.
New Server 2025 features
- Windows Server Hotpatching where in-memory code of processes is updated without needing to restart processes, and applications continue running. It makes for cool demos. Baseline cumulative updates, every 3 months are still required. This seems to require an Azure Arc connection, enabled via Azure portal as a subscription.
- AD enhancements with new forest functional level, support for 32k DB page sizes (upgrade done on forest-wide basis). Now AD servers can take advantage of NUMA nodes, supporting more than 64 cores. Replication priority boost can be set on link basis.
- LDAP support for TLS 1.3, and a bunch of kerberos and LDAP changes. SMB mailslots (net send) being removed, and no longer used by domain controllers.
- Working towards a world without NTLM. Local KDC built into windows for local user accounts, IAKerb and SMB security improvements.
- NVMe storage improvements, with a re-written storage layer that can deliver 90% more IOPS on NVMe SSDs. Aside from a storage rewrite there’s finally an in-box NVMe-oF TCP initiator.
- Storage replica performance enhancements (3x) with compression available in all editions of Windows Server.
One feature to highlight is ReFS native dedupe based on block cloning. This one is interesting, because Veeam has supported block cloning on ReFS for years. The design goals here are for hot data - server workload use cases - so use it to save money on those expensive disks - do not use it for backup storage. While I believe we did QA validation that no conlicts occur, this is not meant for volumes with the size and characteristics of Veeam repositories!
There is still the question of the RCT issues that were addressed to some extent by Microsoft in October last year. We have a thought that some of it may be related to buffered vs unbuffered IO. This is still being looked into further - but will keep you updated.
If you want to try Server 2025, you can check out the insider pages for the latest builds, as of writing the latest is build 26085 released March 27th. Official support does not come until after GA of course.
Anyways - hope this was helpful to someone - and looking forward to learning who else is trying Hyper-V 2025...
