https://bugs.winehq.org/show_bug.cgi?id=51945
--- Comment #2 from Louis Lenders xerox.xerox2000x@gmail.com --- (In reply to Nikolay Sivov from comment #1)
It returns some fixed value, see dlls/mountmgr.sys/device.c for IOCTL_DISK_GET_DRIVE_GEOMETRY_EX.
Thanks for the info, i see where it comes from now ( 255 * 63 * 512 whereas Windows reports real size of disk)