I have a huge Photos library (400GB+) that I have backed up to iCloud. I chose to optimize the library so that it would continue to fit on MacBook Air's hard drive. However, it's making me nervous to have all my originals in the cloud though with no non-cloud backup. However, I do not have enough hard drive space to download my originals to my mac. I want to duplicate my Photos library to my external drive. What is the best way to do this? Should I create a new empty Photos library on the external drive and then let iCloud import all the photos to it? If I just paste my current optimized library to the new drive I get a weird message about deleting photos which freaks me out. What's the best way to do this?