How to Move Your Apple Photos Library to an External Drive Safely

Your Photos library is often the single largest consumer of disk space on a MacBook, routinely reaching 100 GB to 300 GB. Moving it to a portable USB-C SSD (like a Samsung T7 or SanDisk Extreme) is the best way to reclaim space, but doing it incorrectly can break iCloud Photos synchronization or lock your database.

Rule 1: Never Use ExFAT or Windows Formats

Apple Photos strictly requires a filesystem that supports macOS extended attributes, hard links, and package bundles. Never copy a Photos library to an ExFAT, FAT32, or NTFS drive. It will result in corrupt SQLite metadata and lost album groupings.

Open Disk Utility.app and format your external drive as APFS (or Mac OS Extended Journaled for older mechanical HDDs).

Rule 2: Check "Ignore Ownership on this Volume"

Select your external drive in Finder, press Command + I (Get Info), expand the "Sharing & Permissions" section at the bottom, and check the box for Ignore ownership on this volume. This prevents permission conflicts across different user accounts.

Rule 3: Designate the System Photo Library

After copying the library to your external drive:

1. Hold down the Option (⌥) key and click the Photos app icon in your Dock.
2. Select the library located on your external drive and click Choose Library.
3. In Photos, go to Photos → Settings → General and click Use as System Photo Library.

Once you verify that all albums, Live Photos, and videos load smoothly, you can safely delete the internal copy from ~/Pictures/.