How to put Photos.app main library on an external disk? I am using the new Apple Photos app on Yosemite, but I don't want to use iCloud for my photos, and I don't want to keep all of them on my computer. So I as wondering if it is possible to have my main photo library on an external network drive, and to sync only some of them with my computer.
You can change the library location from the Preferences window on the General tab. Photos &gt; Preferences... and select the General tab.

At the top where it says Library Location: click the Show In Finder button:



In the Finder window that opens, move the Photos Library.photoslibrary to the place where you'd rather it exist. This can take some time if it's a large library.

Once it's moved, double click on it in Finder and your Photos app will update and point to the new location.