I have a couple of terabytes of 3in GeoTIFFs that I would like to host on my GeoServer (used by a non profit during disasters when there is no Internet). I have read that the best way to host these images is my creating mosaic overviews so that the client is not trying to load terabyes of data at a time. I have looked at gdal_retile but that appears to be doing the opposite of what i am trying to do. I have the most zoomed in image and want to create the mosaics for overviews.
I am using GeoServer and QGIS as my client.