Image Manager With Multiple Databases?

I have several external hard drives with pictures. What I am looking for is an image manager that allows me to have several independent image databases. I personally want one for each hard drive, but since they are mounted as folders the programs would just need to have multiple databases of some sort. That way I can move the hard drive to a different computer with the same program and open that database, or open the database just for that hard drive over a network. I also want all the normal stuff, tagging, ratings, ratings and tags saved to metadata, etc. digikam has all the other features I want but currently only supports one giant database. Does anyone have any alternatives?