Sean Elliott (UK) (11/7/2011)

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Be aware that using the /z switch (restartable mode) for Robocopy slows it down massively cant tell you how much but something like half speed. You are better off not using /z in general and just recopying the whole file again in the rare event it fails part way through.

I have just been doing something identical to this but I found Robocopy to be far too slow for large files ie > 20GB. It also seems to cause file corruption (silently) somewhere in the range 30GB to 70GB. I can copy 30GB files but not 70GB files. You can prove that a file is identical (or not) easily using the Microsoft utility called FCIV which creates a hash value for a file:

http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=11533

There is a much quicker way to copy very large files using a Microsoft utility called ESEUTIL. I have just spent my entire weekend migrating 280GB of backup files across a network using this. It runs much faster than robocopy and does not corrupt the files.

Don’t believe me about ESEUTIL? See this for evidence that using ESEUTIL is a sensible thing to do (bottom of page post by Jacob Luebbers Posted 5/22/2008 2:05 AM:

http://www.sqlservercentral.com/Forums/Topic495042-357-1.aspx

(also see the other posts he refers to – I have seen other posts on same topic too)