Incomplete files moved on Windows NFS

  locking, move, nfs, powershell, windows

I have a Unix system mounting an NFS "share" from a Windows server. On the Windows server I have a PowerShell script that will check every 10 s if there is a new file coming in on the NFS share and Move-Item it somewhere else and then it gets processed further.

What we are seeing is that files are corrupted in this process. My hunch is that the NFS writing takes a little longer, the script picks up an incomplete file and Move-Item it to the other folder. There is also a theory a colleague has that the further processing picks up the file before Move-Item has completed. I do not believe in that theory, because Move-Item on the same file system should be an atomic metadata only operation. (Don’t be confused by the NFS reference, the Windows server has these files locally, the NFS share is mounted by the Unix system, so Move-Item does not involve NFS, and in my case, doesn’t cross file system boundaries either.)

Either way, I want to know why it would be that the writing of the file to NFS which is by a Java process on Unix, is not locking the file on the Windows host file system? Would I have to explicitly on Java cause an NFS lock to be set somehow? Is there even support for fcntl lock feature from Java?

Also, if I used power-shell Copy command rather than Move-Item, there would be a certain moment of file incomplete copied. Isn’t the Copy command automatically setting a lock on the destination file until it is finished?

Source: Windows Questions

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