Throttle File Copy and other Advanced Copy Situations in Windows


At one time, maybe a year ago, I was trying to find a way to copy big files around a small network without choking the network and / or the sending or receiving computers.

Well, I've finally found it. The utterly useful Robocopy utility from the Windows Resource kit has a

/IPG:n : Inter-Packet Gap (ms)

flag that will delay each subsequent packet.

IPG - will send a 64 KB packet followed by a delay of n Milliseconds. If my math is correct, a 1ms delay every 64KB would generate a maximum of 6 MBps - but it's actually much less on a 100Mbps LAN because it would take a significant portion of the time to transmit the packet.


- note the tricky 3rd parameter specifying the filter, this is different from the regular Windows / DOS copy or xcopy syntax.

robocopy "d:\Company Shared Folders\IT" \receiving2\c$\backups *.bkf /ipg:10 /zb

- for a single file from current folder (".") to w: drive using ipg to give other users a chance to access files: robocopy . w: really-big-file.img w: /ipg:4



ROBOCOPY source destination [file [file]...] [options]



Robocopy does not do authentication. To copy to network shares on different domains... something like this can work:

net use \\server1\g$ /user:domain1\user1 * 

net use \\server2\g$ /user:domain2\user2 *

robocopy \\server1\G$\testdir\%3 \\server2\g$\uploads



2007-06-23:  Another tool, supercopier, this one with a GUI. Haven't personally tested it yet:

Update 2008-02-20:
I had a need to try this today.  Only the GPL source code is on Sourceforge. Visit the homepage for binary install for Windows:

Update 2014: This seems to be infected by malware these days. :(

This program works great! There's a simple drop down to limit the transfer to 1, 2, 4 or custom MB/sec.



Copying all files that have been changed recently


Robocopy changed files -

ROBOCOPY source_folder destination_folder [file(s)_to_copy] [options]

/E = empty -- don't use... seems to occur before MAXAGE, so, a LOT of folders get created

/S = subfolders

/L = list only

/Z = network restartable


ROBOCOPY "D:\Company Shared Folders" "D:\ToMove" *.*  /Z /S /MAXAGE:10 

ROBOCOPY "D:\Users Shared Folders - Delete in 2013" "D:\ToMoveUsers" *.*  /Z /S /MAXAGE:10 


ignore errors while copying: robocopy c:\ d:\ /MIR /R:0 /W:0


The Reg List

A fellow tried to move 60 million files.  Mentions "richcopy" and ultimately uses Linux as a middle man to handle really deep folder trees.




Unfortunately, it's time to avoid xcopy. Even though I used it for decades, xcopy on XP will bomb if the file path hits a 254 character limit, thereby baffling everyone. Try robocopy.

xcopy - continue if errors found (e.g. bum spots on disk): xcopy /C/H/R/S/Y c:\ d:\


relevant notes

Windows Vista added i/o priority. There are tools that will let you adjust programs to have low disk priority.

e.g. (not tested)

Tags: Win, w2k, winxp, xcopy, robo copy, slow, file, backup, mirror, speed, robocopy, supercopier, 

Related Scribbles:
  • System Administration
  • Throttle Processes Windows and Start Syntax
  • Utilities
  • Utilities for Microsoft Windows
  • Windows

  • ID: 779
    Date Updated:
    2016-06-23 13:03:06
    Date Created:
    2006-08-02 16:10:58


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