Multi-threaded robocopy for faster copies

Grant Holliday’s blog

Senior Service Engineer, Microsoft Visual Studio Team Foundation Service

Multi-threaded robocopy for faster copies

  • Comments 4

Windows 7 and Windows Server 2008 R2 include an updated version of Robocopy that includes a multi-threaded copy feature.

/MT[:n] :: Do multi-threaded copies with n threads (default 8).

I’ve been using this for a while now and I’ve been seeing excellent results. Be careful with who you share a switch with though – I managed to saturate my 100Mbit switch so badly that my fellow switch neighbors started getting timeouts. My favorite usage is:

robocopy \\server\share\folder C:\Temp\folder /S /MT /Z

This copies the contents of the remote folder, with 8 threads in restartable mode – great for when you’re on a slow or unreliable link.  Also note that the progress monitors don’t seem accurate in multi-threaded mode. It starts copying 8 files at once, but only shows you the progress of 1 of them.

  • Hi Grant,

    Thanks for this post.

    I was wondering, do you ever see issues with the multithread option? I’ve been trying this out, copying from remote to a local share, and it seems like robocopy is freezing up. I don’t get any console output, or output to a log.

    I’m just wondering if others have experienced this behavior.

  • I see the same thing.  The more files there are the longer it takes to begin.  If you are dealing with small folders (<100 files) it is not a big deal, but with large folders it takes forever.  I don't like the MT option anyway.  It seems like it would cause more fragmentation and much more seeking on the read disk.

  • We ran some tests comparing Robocopy with and without the /MT (multithread) option with local disk, 1GbE network and 10GbE network. We tested a variety of numbers and sizes of files. I gave a presentation at our local user group meeting, and the presentation is available at www.demartek.com/Demartek_Presenting_RMWTUG_March_2011-03.html. The /MT option provides improved performance and in some cases, significantly improved performance.

  • For me robocopy in /MT:10 is slowest. Copy files in 30 sec. copy and without /MT in 28sec.

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