I have a whole series of GeoTiff tiles, each one about 250mb in size, in total just over 90gb. I want to be able to display these as a wms into QGIS to 20+ GIS users and in the end make them into a tile cache. My problem is that I don't have enough server space to stick the GeoTiff tiles on to in their current state, so they are living on an external hard-drive. My server contains GeoServer and I've also got access to MapServer on the same server but I'm less fluent its configuration than I am with GeoServer.
Is there a way that I could reduce the size per GeoTiff to make them more manageable or should I convert them into another file tile, png/jpeg2000 for example?
Has anyone else any experience of such large GeoTiff sizes and what did you do with them?
Oh and I'd like to do this entirely with OpenSource (if possible).