problem with rsync usage across NFS

[HP Wei]

I am using rsync version 2.3.2 on Sun (SunOS 5.8).
And I encountered the following problem that I hope the
guru of rsync on this list can shed light on.


The configuration is depicted as follows:

                rsync
 Sun data file  ----->  NFS file server  (nfs)
                          |
                          |
                  Linux_nfs_clients (lin)
                  
------------------------------------------------------------------                  
Here are the steps that will lead to a problem.
(1) On sun, a textfile file is generated in directory, say, /sun/test/
    We use the following to deliver it to the NFS server's empty
    direcotry /nfs_path/test/:
    rsync --verbose --archive --hard-links --whole-file  --delete --delete-after 
    --exclude='*_bak*' --backup --suffix=_bak123 
    /sun/test/ /nfs_path/test/
    
(2) We login to one of Linux clients.
    And we do the following
    tail -f /nfs_path/test/file
    
(3) On Sun, we update the file.
    And we use the same rsync command as listed in (1) to deliver the 
    data file.
    
(4) We login to the same linux machine as in (2) in another window.
    And do
    ls -l /nfs_path/test/
    
    We expect to see two files,  file and file_bak123
    where file is the new version.
    
    Instead, we see just one file: file (the old version).

--------------------------------------------------------------------
** if in the first step, we use 'cp /sun/test/file /nfs_path/test/',
   and continue with (2)-(4) exactly as above,
   we can get the expected two files!
   
    
Does anyone bump into this problem before ?
How do we deal with this situation ?

HP