SMB 2.1 and Multithreaded Robocopy

The latest and greatest version of Microsoft’s Server Message Block protocol for file sharing in Windows networks is 2.1, which ships with Server 2008 R2 and Windows 7. In previous posts I’ve mentioned some ways in which this new SMB protocol may speed file copies over the network. But here’s a surprising benefit: it has permitted one of our old friends, Robocopy, to work significantly faster in cases where you’re copying a lot of files. The reason is that Robocopy has always been synchronous, i.e. non-parallel, when it comes to transferring file metadata. If you have a lot of files, especially small ones, the metadata becomes a higher percentage of the total bits transferred, and the lack of parallelism hurts performance. But with SMB 2.1 and the new version of Robocopy, full multithreaded operation is supported and we should therefore see better performance in these scenarios. So where does that leave those of us who might not be able to use SMB 2.1 just yet, for example, because we haven’t yet moved to Windows 7? Well, if you’ve ever used the Robocopy GUI written by Microsoft’s Derk Benisch, it includes the ability to create Robocopy scripts which you can execute in parallel. (Plus the GUI is pretty cool.) However, another Microsoft employee, Ken Tamaru, has written something even nicer called RichCopy. This also gives you a GUI and multithreading. It’s free and slick although (alas) unsupported. Nevertheless I suggest you check it out.