I am using a lightroom 5 in mac osx and store all the photos and the catalogue on the 1T 3.5" external drive that need power supply. I name the drive 1T tm (I like it this way since I can plug this drive to any mac has the lightroom5 to edit the photos) recently I got a 500g 2.5" portable drive, and I use it with carbon copy cloner to backup the picture folder with the lightroom 5 catalog. Now that I like this 2.5" portable drive and want to use this as my work drive and swap the 1T big drive for my backup. But the question is when I hook this up to lightroom it is ?? mark on all the photos, since the link is not right. If I rename the portable drive to 1T tm then it is ok, but I hope to find a better way to fix this problem. please suggest what is the best way to add external drive that is already has all the photos on it and using it. I saw some people like to keep the LR catalog in the system. but I am worry about if the system down than I have nothing to work with, how do you fix this problem. thanks.