Windows Server Insiders Get Quick Recovery, ReFS Boot, and NVMe-oF

Windows Server Build 29621 is now available to Insiders with Quick Machine Recovery, ReFS boot support, Trusted Launch improvements, and NVMe-over-Fabrics.

Microsoft released Windows Server vNext Insider Preview Build 29621 as part of the Windows Server Long-Term Servicing Channel Preview.

The preview includes Desktop Experience and Server Core installation options. Microsoft offers Datacenter, Standard, and Azure editions, although the Azure Edition should only be used for virtual machine evaluation.

Trusted Launch improves virtual machine security

Trusted Launch for virtual machines is one of the main security additions in Windows Server Build 29621.

The feature protects Hyper-V Generation 2 virtual machines during startup and operation. It supports security technologies such as Secure Boot and virtual Trusted Platform Modules.

These protections can help prevent attackers from modifying firmware, boot components, or other sensitive parts of a virtual machine before the operating system starts.

Microsoft has also published separate guidance covering Trusted Launch requirements and current limitations.

Quick Machine Recovery reaches Windows Server

Build 29621 introduces Quick Machine Recovery to the Windows Server preview.

Microsoft originally announced the feature for consumer editions of Windows 11. It helps systems recover automatically from certain startup failures without requiring administrators to perform complicated manual repairs.

When a supported device cannot start correctly, Quick Machine Recovery launches through the Windows Recovery Environment. It then connects to Microsoft’s cloud services and searches for an applicable remediation.

The system can download and apply an available fix before attempting to start Windows again.

Quick Machine Recovery forms part of Microsoft’s wider Windows Resiliency Initiative, which aims to reduce downtime caused by widespread boot failures and faulty updates.

Microsoft plans to introduce a Group Policy setting for managing Quick Machine Recovery in a future preview build.

ReFS boot support requires a larger recovery partition

Windows Server Build 29621 also enables booting from the Resilient File System.

ReFS offers features designed to improve data integrity, scalability, and protection against storage corruption. Its addition as a boot option expands its use beyond data volumes and specialized storage deployments.

Systems that boot from ReFS create a Windows Recovery Environment partition with at least 2GB of available space.

Administrators should account for this requirement when preparing disks or testing deployment configurations.

Windows may disable WinRE when it cannot update the recovery environment because the partition does not contain enough free space. Disabling WinRE does not automatically delete the existing recovery partition.

Microsoft also warns that deleting the WinRE partition and extending the boot volume into the freed space cannot be reversed without performing a clean Windows Server installation.

NVMe-over-Fabrics expands remote storage support

The latest Windows Server preview introduces support for NVMe-over-Fabrics, also known as NVMe-oF.

NVMe-oF extends the NVMe protocol from locally connected PCIe storage to remote storage devices accessed through a network.

Servers can communicate with remote NVMe controllers by using the same NVMe command set used for local drives. This design can deliver better efficiency and lower latency than older SCSI-based storage protocols.

The feature provides an alternative to technologies such as iSCSI and traditional Fibre Channel storage.

NVMe/TCP and NVMe/RDMA options

Windows Server supports NVMe over TCP for environments using standard Ethernet networks.

NVMe/TCP does not require specialized networking equipment, making it easier to test or deploy with existing infrastructure.

NVMe over RDMA targets workloads that require lower latency and higher throughput. Supported RDMA technologies include RoCE and iWARP.

Administrators need compatible RDMA network interface cards to use NVMe/RDMA.

Windows Server Build 29621 availability

Microsoft has documented additional known issues that may affect Windows Server Build 29621.

Windows Server Insiders can download the latest Long-Term Servicing Channel Preview through Microsoft’s official Insider distribution channels.

In related news, Microsoft has released its July 2026 Patch Tuesday updates, including Windows 10 KB5099539 and Windows 11 KB5101650 and KB5099414 updates.