By default, Apple’s Spotlight search in OSX doesn’t appear to index mounted network drives successfully if at all regardless whether the drives are mounted as AFP or SMB. There is a way for turning on search for specific network drives using terminal however it has found to be problematic and quite often needs reindexing when mounting the drive again. This can place stress on your server’s resources and can be a real pain having to go in to terminal to accomplish what is a seemingly simple task which Windows users take for granted. We have found the easiest way to search mounted network drives in OSX is to install a third party app from the App Store. There are paid for versions however we have found this free version works quite well. It’s called Easy Find.
Once you’ve installed Easy Find all you need to do is select the location you want to search, choose whether to search for file name / file contents etc.. and hit return.