Apple has long offered a way for you to access the startup volume on one Mac as a drive that appears on another that’s directly connected. Until recently, that methods was known as Target Disk Mode, and it remains in place for all Intel Macs. New Apple silicon Macs with an M1 processor rely instead on Share Disk (sometimes called “Mac Disk Sharing”) that requires an entirely different path.
Regardless of the Mac’s vintage, you start with a cable connected between like ports on the two Macs:
- With an Intel Mac, connect a FireWire port to a FireWire port (remember FireWire?) or a Thunderbolt port to a Thunderbolt port.
- With an M1 Mac, you can use USB 3.0 (Type-A to Type-A), or a USB-C data cable that handles either USB 3.1 Gen 2 or later or Thunderbolt 3.
For an Intel Mac, you enable Target Disk Mode and restart:
- From the Startup Disk preference pane, click Target Disk Mode.
- Restart your Mac.
- The startup volume appears in the Finder of the other Mac as if it were a mounted volume from an attached drive.
Instead of steps 1 and 2, you can also restart and hold down the T key during startup.
You can now transfer, open, and delete files. When complete, eject the volume. Hold down the power button on the sharing Mac until it powers down to exit Target Disk Mode. You can then restart into macOS normally.
With an M1 Mac, more steps are involved because of a new security approach that requires authentication at more steps. This also shares the disk as a networked volume instead of a directly connected drive. Here’s how:
- Choose > Shut Down.
- Once your computer is fully powered down, hold down the power button until you see Loading Startup Options.
- Click Options and click Continue.
- Select an account on the Mac you’re sharing and enter its password, then click Continue.
- Choose Utilities > Share Disk.
- Select the disk to share; an M1 Mac lets you share any internal or attached drive. Click Start Sharing.
- On the Mac you want to access the volume from, choose Go > Network, select the Mac in the list that appears, click Connect As in the upper-right corner, select Guest, and click Connect.
After you’ve interacted in whatever way you see fit with the mounted Mac volume, eject it. Then click Stop Sharing on the sharing Mac. Choose > Restart to resume using macOS on that Mac.
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Roman has covered technology since the early 1990s. His career started at MacUser, and he’s worked for MacAddict, Mac|Life, and TechTV.