Back Up Your iPhone to an External Drive Using a Symlink

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If you’re like me and have a Mac with expensive and limited internal storage, backing up your iPhone can quickly become a headache. iPhone backups created through Finder (or iTunes on older macOS versions) are stored by default in:

~/Library/Application Support/MobileSync/Backup

These backups can easily eat up tens or even hundreds of gigabytes. Fortunately, there’s a simple trick to offload those backups to an external drive without changing how Finder backs up your device: use a symbolic link (symlink).

The Problem

I was running out of space on my Mac’s internal SSD. My iPhone backups were taking up over 75GB, and I needed a way to free up that space without losing my backup history or relying on third-party software.

I needed a permanent solution that would:

  • Let me store backups on an external SSD
  • Work seamlessly with Finder without any third-party tools
  • Require minimal setup

The Solution

I moved the backup folder to an external SSD and created a symlink that tells macOS to treat the external location as if it were the original backup folder.

Here’s the command I used:

ln -s /Volumes/SSD/iPhone/Backup ~/Library/Application\ Support/MobileSync

What it does:

  • ln -s: creates a symbolic link
  • /Volumes/SSD/iPhone/Backup: the new location on the external SSD
  • ~/Library/Application\ Support/MobileSync: the original location expected by macOS

After this, Finder will back up your iPhone as usual—but the actual data will be written to your external SSD.

Step-by-Step Instructions

  1. Connect your external drive to your Mac and make sure it’s mounted. You can check this in Finder or by running:
ls /Volumes
  1. Create the destination folder on your external drive:
mkdir -p /Volumes/SSD/iPhone/Backup

Note: Replace /Volumes/SSD/iPhone/Backup with the actual path to your external SSD where you want to store the backups.

  1. Remove the existing backup folder:
rm -rf ~/Library/Application\ Support/MobileSync/Backup

Note: This will delete your existing backups, so make sure you have them saved elsewhere if needed. If you want to keep them, you can rename the folder instead:

  1. Create the symbolic link:
ln -s /Volumes/SSD/iPhone/Backup ~/Library/Application\ Support/MobileSync
  1. Back up your iPhone via Finder. The data will now go to your external drive!

Notes

  • Your external drive must be connected when you back up your iPhone.
  • If it’s not connected, backups will fail.
  • Once you confirm it’s working, you can safely delete the MobileSync_old folder if you want.

Final Thoughts

This trick saved me over 75GB of space on my internal SSD and works flawlessly. If you regularly back up your iPhone and are tight on space, a symbolic link to an external SSD is a clean and efficient solution.

No third-party apps. Just a terminal command, and you’re done. ✌️

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