Moving your photos from the photo library to an external drive is easy. But, it is highly recommended that before you begin moving photos, you should backup your photo library to any other location or a cloud account to make sure that if anything happens to your photo library, you have a copy safely backed up on to another location or a cloud account.
- To share your photo library, you need to move the library to a volume where ownership is ignored.
- Connect an external USB, FireWire, or Thunderbolt drive which has enough free space to contain the library.
- Be sure to choose a locally mounted drive. Storing your library on a network share can lead to poor performance, data corruption, or data loss.
- Select this drive in the Finder.
- Choose File > Get Info.
- In the Info window, find the Sharing & Permissions section. You might need to click the triangle next to Sharing & Permissions to see the details for this section.
- Click the lock in the lower-right corner of the Info window. Enter an administrator name and password when prompted.
- Select the option to Ignore ownership on this volume (usually selected by default).
Note: If you've already selected this volume for use as a Time Machine backup, you won't be able to select the option to ignore permissions. Select a volume you're not using with Time Machine as the destination of your shared library.
- Copy your library to this drive. By default, libraries for Photos and iPhoto are located in the Pictures folder within your home folder.