Tech Tip for Mac Users, Move Your Photos Library To An External Drive For More Space

I've been hoping to get back into photography, but two things were discouraging me. The cost of film is increasing and my MacBook has limited storage space on the internal SSD so storing a lot of RAW files would not be ideal. When I switched to using Apple's Photos app to manage my photos I thought I was required to use the internal SSD. I have an external drive for larger files, which I have configured with Time Machine as I used to store my digital photos there.

If you plan to do this, Apple does have instructions which I will repeat here, however, this is discouraged as Time Machine does not backup external drives by default. You want to make sure you have Time Machine making a backup of your external drive that you are using for photos prior to moving your library.

This had been discouraging me for quite a while, but I need to explain my workflow first to show the impact of film versus digital on my storage requirements. With film photography, I do not have the large RAW files that I do with my digital photography. When I have my film processed at a lab they scan to JPEG images and any editing that would need to be done is usually performed during the scanning process. I do not need large TIFF files. With digital, I'm on my own for editing and trying to get the best image out of what I captured. This means I need to capture a RAW file from my Canon DSLR which is around 17 or so megabytes per image instead of about 3 to 6 megabytes per image. Even a large number of film photos would eventually cause difficulty with my SSD space.

If you wish to move your photos library to an external drive, you need to perform the following steps.

1. Select the external drive you wish to move the library to, this drive should be one that is usually connected to your machine and one that is included in Time Machine backups. This drive must be formatted as Mac OS Extended (Journaled) or APFS. You cannot use a time machine drive or a drive formatted in another format such as FAT or exFAT.
1. If you are not sure how to configure an external drive to be backed up by Time Machine I will follow up with an article on how to do this.
2. Close the Photos application if it is open. Also ensure that no devices such as iPhones or iPads will sync to your Mac during this process.
3. Locate your Photo's Library folder in the Finder. This is usually in the pictures folder in your home folder. Note this appears as a file that opens in Photos, but is technically a folder.
4. If needed, open another Finder window and open your external drive.
5. Drag the Photos Library folder from the source to the external drive. This only copies the folder, we will remove the old folder.
6. Double click on the Photos Library folder on the external drive, this will launch Photos.
7. Go to the Photos menu and select preferences. Ensure that the library location indicates your external drive. Click the "Use as System Photo Library" button.
8. At this point iPhones and iPads can sync again.
9. If your desktop wallpaper is stored in photos, you should drag this individual photo to the Pictures folder and reset your wallpaper to one of the default options and then to the file in the Pictures folder. This ensures the correct wallpaper is displayed even if the Photo's Library is not available.
10. Next find the old Photo's Library folder and move it to the Trash/Bin. Do this with Photos open so it will not let you remove the wrong copy. Do not empty the Trash/Bin yet.
11. Perform a Time Machine backup, ensure that the backup is larger than the size of your photos library. If you have multiple Time Machine drives, repeat this step until all the backup is made to all Time Machine drives.
12. Close and re-open Photos to be absolutely sure the Photos Library is configured correctly. When re-launching, launch from the dock, Applications folder, or Launchpad to ensure that Photos is defaulting to the correct folder.
13. Once Time Machine is fully updated, you can empty your trash to remove that large Photos Library from your internal drive.