https://bugs.winehq.org/show_bug.cgi?id=55029
--- Comment #10 from Alex Xu alex_y_xu@yahoo.ca --- windows supports CoW in CopyFile now: https://devblogs.microsoft.com/engineering-at-microsoft/copy-on-write-in-win.... I think previously CopyFile called IOCTL_COPYCHUNK which is still only for network shares, and now also calls FSCTL_DUPLICATE_EXTENTS_TO_FILE which is only for ReFS.