Log only changes in robocopy output

It sounds like rsync is definitely what you are after. You do not need to set up an 'rsync server' to copy files from one machine to another. Rsync supports copying files over SFTP (SSH File Transfer) which most linux boxes have enabled already (if not manually disabled).

See Lifehacker's Mirror files across systems with rsync for more details:

Whether you want to backup your data, distribute files securely or mirror your working documents over the internet from the office to home, between computers on your local network, or from your computer to your web server, rsync can get the job done. Today we'll use rsync to mirror folders between a Mac and PC over a secure connection at the command line.

Rsync is free (as in speech) and cross platform, meaning it syncs files between operating systems (Windows/Cygwin, Mac OS, Linux); it works over ssh so it's encrypted and secure; unlike FTP it's incremental, so only the parts of changed files are transferred, not whole files, which makes it go like Speedy Gonzalez; and the fact that it's command line makes it scriptable and easily automated.

The short answer is that when robocopy is copying these folders from one server to another, I suspect that it is seeing the timestamps differently than you expect, so it is deciding that the existing files on the destination are older than the same files on the source. This could be due to differences in the time/timezone/DST settings on the two machines.

When robocopy analyzes the files before copying, it classifies each file into one of these classes:

Lonely files:  exist on source but not destination.
Newer files:   have Newer timestamp on source, (size and attributes: N/A).
Older files:   have Older timestamp on source, (size and attributes: N/A).
Changed files: have same timestamp, but different size (attributes: N/A).
Same files:    have same timestamp, size, and attributes.
Tweaked files: have same timestamp and size, but different attributes.
Extra files:   exist on destination but not source.
Mismatched:    is a file on one, and a directory on the other, in source
               and destination.

By default (and with the command line options you have given), robocopy will copy Lonely, Newer, and Changed files. Files in the other classes will not be copied, and will either be simply reported in the output and/or log, or completly ignored.

If robocopy is copying a file and overwriting an existing file on the destination, then robocopy thinks that either the timestamo of the source file is before (Newer) the timestamp of the destination file, or the file sizes are different (Changed).

In order to tell exactly what's happening to each file, you could run robocopy with the "/L" and "/V" command line options. Using the "/L" options tells robocopy to not do any actual copying, and only list what would otherwise be copied. Using the "/V" options tells robocopy to to provide Verbose details.

This will show why robocopy has decided to copy (and skip) each file. So, for example using robocopy to copy an example fileset.

Here is a listing of the files:

 Directory of C:\folder1

02/28/2014  12:48 PM               327 File1.txt
02/28/2014  02:03 PM               333 File2.txt
               2 File(s)            660 bytes

 Directory of C:\folder2

02/28/2014  12:43 PM               327 File1.txt
02/28/2014  02:03 PM               327 File2.txt
               2 File(s)            654 bytes

In this example, the files named File1.txt, are the same size in the source and destination folders, but has a Newer timestamp in Folder1. And, the files named File2.txt, have the same timestamp in the source and destination folders, but have different (Changed) file sizes.

Running robocopy to copy Folder1 to Folder2, with the "/L" and "/V" command line options looks like this.

C:\>robocopy "C:folder1" "c:folder2" /E /L /V

-------------------------------------------------------------------------------
   ROBOCOPY     ::     Robust File Copy for Windows
-------------------------------------------------------------------------------

  Started : Fri Feb 28 21:07:29 2014

   Source : C:\folder1\
     Dest : C:\folder2\

    Files : *.*

  Options : *.* /V /L /S /E /COPY:DAT /R:1000000 /W:30

------------------------------------------------------------------------------

                           2    C:\folder1\
            Newer                    327        File1.txt
            Changed                  333        File2.txt

------------------------------------------------------------------------------

               Total    Copied   Skipped  Mismatch    FAILED    Extras
    Dirs :         1         0         1         0         0         0
   Files :         2         2         0         0         0         0
   Bytes :       660       660         0         0         0         0
   Times :   0:00:00   0:00:00                       0:00:00   0:00:00

   Ended : Fri Feb 28 21:07:29 2014

If you run robocopy with the "/L" and "/V" command line options on your set of files, it should give you the information of why robocopy is unexpectedly copying these files.

I suspect that robocopy is seeing the timestamps differently than you expect, and is deciding that the files on the source are Newer than the same existing files on the destination. This could be due to differences in the time/timezone/DST settings on the two machines.