We've recently deployed Exchange 2013 SP1 as an upgrade from 2007. We are using the In-Place Archive feature that Exchange 2013 has. Using OWA however we do not seem to have the option to do a combined search of both the archive and active mailboxes.
This looks like it should be a possibility based on the screen shots seen here:
http://support.pa.msu.edu/howto.php?id=134
Specifically this one:
http://support.pa.msu.edu/images/owa/img6.png
Any thoughts as to why we seem to be missing this feature? And let me know if you need any further info.