I'm investigating how SharePoint Server 2010 search works, especially which technique is used to propagate the index (generated by the crawler) to the query server. In SP2007 the index was stored locally and copied to the query server(s) using UNC, as far as I know. In SP2010 this changes and no local copy is preserved. But, how is it copied / streamed to the Query server? Using UNC? Using web services?
None of the diagrams / technet articles / blogs I've seen explained this in detail, it's just saying "the crawler propagates / streams the index to the query server".