New features in the Windows Server 2016 ReFS file system for virtualization

Windows Server 2016 introduced major improvements to the ReFS (Resilient File System), especially for virtualization workloads. If you're using Hyper-V, ReFS can make creating and expanding VHDX files much faster.

Here are some highlights:

• Block cloning: copies large VHD files almost instantly by referencing existing blocks instead of duplicating data.
• Sparse VDL (Valid Data Length): speeds up fixed-size VHDX creation by avoiding zeroing out unused space.
• Automatic integrity streams: optional metadata checksums for improved resilience.
• Improved scalability: supports larger volumes and faster metadata operations compared to NTFS.

To create a ReFS volume, use PowerShell:

New-Volume -FileSystem ReFS -DriveLetter R -FriendlyName "VMStorage" -Size 500GB

Or reformat an existing volume (after backups, please):

Format-Volume -DriveLetter R -FileSystem ReFS -Force

ReFS is best for Hyper-V data disks and storage spaces, not for boot drives or workloads that require deduplication. For those, you can continue using NTFS.