programatically wiring binary data to a file on a VBoxSharedFolderFS disk fails

[exoer]

I made a python program to write binary data to a file on my shared disk. It has the filesystem VBoxSharedFolderFS. When the data became over a certain size only 0s was written. I used the numpy.tofile() method and also used a more direct way writing the data. f = open('z:\some_file.bin', 'wb') f.write(data.tostring()) which also failed on the shared disk, but there was no problem on the local disk.