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Brian Donahue
Asked: 2010-02-25 15:27:07 +0800 CST

Robocopy really slow across LAN

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DISCLAIMER: I'm a programmer, not an admin!

I am setting up web apps in a new server cluster and copying files using xcopy or robocopy and UNC paths between servers on the same subnet is really slow. SOmetimes it seems to sporadically speed up, other times it is taking 2+ seconds to copy 5K files. On our old environment this was lightning fast. The only difference I know of is that was Win2K3 and this is Win2K8. Could OS have anything to do with it, or is this more likely a weird network issue causing this?

file-transfer robocopy xcopy

4 Answers

  1. Try adding /MT and removing /Z. This worked like a charmm for me:)

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  2. Have you considered the possibility that your new server cluster has a different virus-killer, which might be set up incorrectly.

    Just a thought, but this can slow filetransfers sometimes.

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  3. Double check you don't have TCP Offload enabled as well. That can impact file copy speeds.

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  4. Is it slow in both directions? Is it slow from all other machines to the new box(s)?

    Make sure there isn't a speed/duplex mismatch between a NIC and switch, disable auto-detect if it's on.

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