With many Macs sporting a limited amount of storage — the entry level 11-inch MacBook Air only has 128MB of flash storage, for example — it doesn’t take long to fill up your drive — especially if you take a million photos a week as my wife does. One solution is to move your Photos library to an external drive.
Before doing so, make sure you’ve backed up your library of pics (something you should be doing anyway). Then follow these steps:
- Quit Photos.
- Connect the external hard drive that you plan to use to hold your Photos library.
- Move your existing Photos library from your user folder's Pictures section to an external drive.
- Once it’s copied, hold the Option key on your keyboard and open Photos.
- A new window will pop up asking you to Create a New Library, Choose the Selected Library or Other Library.
- Click on Other Library.
- Select the Photo library file on the external drive and pick Choose.
As long as the external hard drive is connected, Photos will reference the library on the external drive instead of your Mac.
Now quit Photos and eject the external hard drive. Open a new Finder window and navigate to the Pictures folder in the left sidebar again. Select the Photos file and move it to the Trash.
Should you now open Photos without the external hard drive with the Photos library connected, the app will inform you that the "Library cannot be found." Quit Photos, connect the external hard drive and reopen the software.