I have an external hard drive that has about 3TB of RAW photo files from my hobby photography. In the past I have done a semi decent job at copying the data to another drive routinely. I'v recently realized one of my hard drives failed and I am down to one copy of all of my photos on a HDD that is 7 years old. I just purchased a new 4TB SSD to make my working drive and a new 8TB HDD that I will use to routinely make a backup of this working drive and then store in a safe place. In the past I have just copy/paste. My question is there a better way to get this copy? I have looked around in Time Machine but I don't see a way to just keep a copy of the external drive. I don't want other files from my computer on the external. I'd like to be able to just plug the two drives in once a quarter or so and click go and a process happens that adds any new changes/files to the backup disk and then eject and store the backup. Thanks in advance!