Windows driver WinBtrfs v1.5 for Linux file system released

[German]Short information for people who want to access Linux Btrfs disks under Windows. The Window driver WinBtrfs v1.5 has just been released. Blog reader Gero S. pointed this out to me (thanks for that). Addendum: Version 1.5 crashes the file system on SSDs.


WinBtrfs is a Windows driver for the next generation Linux file system Btrfs. The new release is a reimplementation from scratch. The driver does not contain any code from the Linux kernel and should work with any Windows version from Windows XP. It is also included as part of the free operating system ReactOS. The features of the driver:

  • Reading and writing of Btrfs filesystems
  • Basic RAID: RAID0, RAID1, and RAID10
  • Advanced RAID: RAID5 and RAID6
  • Caching
  • Discovery of Btrfs partitions, even if Windows would normally ignore them
  • Getting and setting of Access Control Lists (ACLs), using the xattr security.NTACL
  • Alternate Data Streams (e.g. :Zone.Identifier is stored as the xattr user.Zone.Identifier)
  • Mappings from Linux users to Windows ones (see below)
  • Symlinks and other reparse points
  • Shell extension to identify and create subvolumes, including snapshots
  • Hard links
  • Sparse files
  • Free-space cache
  • Preallocation
  • Asynchronous reading and writing
  • Partition-less Btrfs volumes
  • Per-volume registry mount options (see below)
  • zlib compression
  • LZO compression
  • LXSS ("Ubuntu on Windows") support
  • Balancing (including resuming balances started on Linux)
  • Device addition and removal
  • Creation of new filesystems with mkbtrfs.exe and ubtrfs.dll
  • Scrubbing
  • Reflink copy
  • Subvol send and receive
  • Degraded mounts
  • Free space tree (compat_ro flag free_space_cache)
  • Shrinking and expanding
  • Passthrough of permissions etc. for LXSS
  • Zstd compression
  • Windows 10 case-sensitive directory flag
  • Oplocks

Defragmentation, support for Btrfs quotas and Windows 10 reserved storage have not yet been implemented. If a Btrfs file system resides on an MD software RAID device created by Linux, WinMD is also required to display it under Windows.

The new version should be suitable for daily use, but making backups is recommended. The developers also point out that the use of this software is at your own risk. Details can be found on GitHub – download may be found here.

Attention: Version 1.5 corrupts a BTRFS volume

Addendum: I just became aware on Twitter, that Btrfs 1.5 may corrupts the BTRFS volume on a solid state drive.

Details may be found on GitHub.


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