Really odd FTP issue

[woody1]

It sounds like the destination file is being opened for writing, but never closed. That would leave it hanging and presumably the OS would eventually close the open file handle but without any awareness of what had been done to it. This could, in theory, leave the content on disk having been overwritten but the file descriptor not having been told the new length of the file. Then the file would have the new content at the start but have the same length as the old file from the point of view of whatever reads it.

I've never seen UNIX doing anything like this but I guess you never know.

As an experiment, I would try the same FTP transfers (small text file overwriting large text file) from the UNIX server to itself (ie. using the UNIX FTP client). This would take the Windows side of things out of the equation altogether.