I had a project recently which highlighted an issue with deep folder trees and large numbers of small files causing slow transfer rates when moving files between two servers. As part of the migration to an SBS 2011 server tests showed a particular rate of transfer which suggested that overnight transfers of data would be successful.
However the actual runs of data transfer – simply copy and pastes between machines were substantially slower thatn anticipated. Much slower. Re-running tests indicated that the folders in question were large (>80GB) but the real issue was the number of files in each one and the number of subfolders. (in total 1.6Million files)
In this case the only option was to use a file archiver (WInrar) to actually compress the files into a archive on a mapped drive on the remote server. Although this wasn’t as quick as I had hoped it allowed the transfers to completed