I have a 2 TB external hard drive with two partitions - one for storing some files, one for a once-a-day backup of my internal startup hard disk with Carbon Copy Cloner. I notice since a long time that very often when I want to do something on my Mac - like opening an application like EasyFind that I have in my Applications folder, or simply trying to open a file - this external hard drive wants to come to live. I hear it start spinning, I see the light blinking. This process might take up to 10 seconds and during this time my computer is basically stalling. I cannot go on with what I am doing, I have to wait until the external hard drive stops again with its activity. I have two other external hard drives - one with a Time Machine backup, one with a fresh installation of OS X 10.11. These hard drives never become active unless they are actually being used. It is only this one particular 2 TB hard drive that is doing this (and slowing me down). Does anybody know or have an idea what might be causing this odd behavior and how I can prevent it?