Move big files between two Macs without Wi-Fi, cloud uploads, or extra apps.
This trick is for Mac users migrating data, rescuing files, or doing quick offline transfers.
Estimated time: about 5 minutes to set up, then transfer time depends on file size.

Quick Answer

Use Target Disk Mode on an Intel Mac: shut down both Macs, connect them with a compatible cable, start the source Mac while holding T, then copy files from Finder on the other Mac. Eject safely when done.

Prerequisites

  • Two Macs (at least the one entering Target Disk Mode should be Intel-based)
  • A compatible cable (Thunderbolt, USB-C Thunderbolt, or FireWire depending on hardware)
  • Power adapters connected for both Macs during large transfers

Step-by-Step: Turn One Mac into an External Drive

  1. Shut down both Macs completely.
    Expected result check: both displays are off and fans are idle.
  2. Connect the two Macs with the correct cable.
    Expected result check: cable is firmly seated on both ends; adapters are secure if used.
  3. On the Mac you want to access as a drive, hold T while powering it on.
    Expected result check: you see a Target Disk Mode screen icon (Thunderbolt/FireWire style indicator).
  4. On the other Mac, open Finder and look under Devices.
    Expected result check: the target Mac’s disk appears like an external drive and opens normally.
  5. Copy files, then eject the mounted disk before disconnecting.
    Expected result check: Finder unmounts the disk cleanly and no warning dialogs appear.

Common Mistakes

  • Using a charge-only USB cable instead of a data-capable Thunderbolt/FireWire cable.
  • Trying this on Apple silicon as classic Target Disk Mode (use modern alternatives there).
  • Unplugging the cable before ejecting the mounted disk in Finder.
  • Forgetting FileVault or user permissions can block immediate file access.

Troubleshooting

  • Drive does not appear in Finder: restart both Macs, reseat cable, try another port/cable, then repeat the T-key startup.
  • Disk appears read-only: check encryption/permission state and unlock where prompted.
  • Transfer is slow: verify you are using Thunderbolt-grade hardware, not legacy/low-speed adapters.
  • Target Mac stuck in mode: hold power button to shut down, then reboot normally.

Reference Links

Next Step

After your transfer, create a simple migration checklist (Documents, Photos, Desktop, Downloads) and verify each folder on the destination Mac so nothing gets missed.