How to automatically back up and archive my photo library? I have a Macbook Air. I love it, but the hard drive is too small to fit my entire photo library. At this point the hard-drive is full and I need to find a way to move the files to a back-up location. I know I could just buy an external hard drive and move the files manually, but I would rather find a way where I could automate the process of backing up and moving older photos (or better yet, photos not recently viewed) to an external hard-drive and a remote backup location. I know of a few services that will automatically back up the photos (if I remember to leave the app running) but they don't remove the files, and I have no way of knowing which files have successfully been backed up and/or could be restored if I wanted to. So I don't feel like I have enough confidence in my backups to feel like I can delete the files to clear up space.

So I'm wondering if you know of a way to automate this process.
iCloud Photo Library would achieve a very similar end result.

In Photos, click Photos > Preferences, choose the iCloud tab and enable iCloud Photo Library.

If you turn on Optimise Storage, iCloud Photo Library will automatically manage the size of your library on your Mac. All of your original photos and videos are stored in iCloud while thumbnails are kept on your Mac. You can download the original photos and videos when you need them. 

Note that your photos would no longer be stored in any backup you make, but iCloud Photo Library does keep deleted photos and videos for about a month.