Announcing ReFS Boot for Windows Server Insiders

We’re excited to announce that Resilient File System (ReFS) boot support is now available for Windows Server Insiders in Insider Preview builds. For the first time, you can install and boot Windows Server on an ReFS-formatted boot volume directly through the setup UI. With ReFS boot, you can finally bring modern resilience, scalability, and performance to your server’s most critical volume — the OS boot volume.

Why ReFS Boot?

Modern workloads demand more from the boot volume than NTFS can provide. ReFS was designed from the ground up to protect data integrity at scale. By enabling ReFS for the OS boot volume we ensure that even the most critical system data benefits from advanced resilience, future-proof scalability, and improved performance.

In short, ReFS boot means a more robust server right from startup with several benefits:

• Resilient OS disk: ReFS improves boot‑volume reliability by detecting corruption early and handling many file‑system issues online without requiring chkdsk. Its integrity‑first, copy‑on‑write design reduces the risk of crash‑induced corruption to help keep your system running smoothly.
• Massive scalability: ReFS supports volumes up to 35 petabytes (35,000 TB) — vastly beyond NTFS’s typical limit of 256 TB. That means your boot volume can grow with future hardware, eliminating capacity ceilings.
• Performance optimizations: ReFS uses block cloning and sparse provisioning to accelerate I/O‑heavy scenarios — enabling dramatically faster creation or expansion of large fixed‑size VHD(X) files and speeding up large file copy operations by copying data via metadata references rather than full data movement.

Maximum Boot Volume Size: NTFS vs. ReFS

Resiliency Enhancements with ReFS Boot

Check out Microsoft Learn for more information on ReFS resiliency enhancements.

Performance Enhancements with ReFS Boot

Check out Microsoft Learn for more information on ReFS performance enhancements.

Getting Started with ReFS Boot

Ready to try it out? Here’s how to get started with ReFS boot on Windows Server Insider Preview:

1. Update to the latest Insider build: Ensure you’re running the most recent Windows Server vNext Insider Preview (Join Windows Server Insiders if you haven’t already). Builds from 2/11/26 or later (minimum build number 29531.1000.260206-1841) include ReFS boot in setup. 

2. Choose ReFS during setup: When installing Windows Server, format the system (C:) partition as ReFS in the installation UI. 
Note: ReFS boot requires UEFI firmware and does not support legacy BIOS boot; as a result, ReFS boot is not supported on Generation 1 VMs.

Screenshot of the Windows Server Setup UI showing ReFS as a File System format option.

3. Complete installation & verify: Finish the Windows Server installation as usual. Once it boots, confirm that your C: drive is using ReFS (for example, by running fsutil fsinfo volumeInfo C: or checking the drive properties). That’s it – your server is now running with an ReFS boot volume.

Screenshot of PowerShell output showing the C: drive formatted as ReFS.

A step-by-step demo video showing how to install Windows Server on an ReFS-formatted boot volume, including UEFI setup, disk formatting, and post-install verification. If the player doesn’t load, open the video in a new window: Open video.

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In summary, ReFS boot brings future-proof resiliency, scalability, and performance improvements to the Windows Server boot volume — reducing downtime, removing scalability limits, and accelerating large storage operations from day one.

We encourage you to try ReFS boot on your servers and experience the difference for yourself. As always, we value your feedback. Please share your feedback and questions on the Windows Server Insiders Forum.

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Christina Curlette (and the Windows Server team)