When a Mac is on its last legs but still powers on, you do not need to boot all the way into macOS to save your files. Target Disk Mode — called Share Disk on Apple Silicon Macs — turns the whole computer into a plain external drive. Plug it into a second Mac with the right cable and your files appear in Finder, ready to drag to safety.
This guide covers the three flavors (older Intel, T2 Intel, and Apple Silicon), the exact cable you need, and the messy real-world case: a Mac that boots but keeps crashing. If yours will not power on at all, skip to the trade-in section — a completely dead logic board can't share its disk, but the drive may still be recoverable.
What Target Disk Mode actually does
Normally your Mac is the brains and the storage. Target Disk Mode splits those apart: the failing Mac stops being a computer and becomes nothing but a hard drive. A second, healthy Mac becomes the brains. Because the failing Mac never loads macOS, a crashing operating system, a broken login, or a corrupt system folder no longer stops you from reaching your documents, photos, and desktop.
Two things it is not: it is not a repair (it copies data, it does not fix the Mac), and it is not a way to run apps. You are moving files, nothing more.
Which mode does your Mac use?
Apple changed the name and the shortcut over the years. Find your Mac below.
Apple Silicon (M1, M2, M3 and newer) — "Share Disk"
There is no keyboard shortcut anymore. You boot into Recovery and turn on sharing from a menu:
- Shut the Mac down completely.
- Press and hold the power button until you see "Loading startup options," then click Options > Continue to enter Recovery.
- In the menu bar choose Utilities > Share Disk.
- Select your internal drive (usually "Macintosh HD") and click Start Sharing.
- Connect the two Macs with a Thunderbolt / USB-C cable (see the cable warning below).
- On the healthy Mac, open Finder, go to the Network section in the sidebar, and connect to the shared Mac.
Intel Macs with a T2 chip (2018–2020)
These use the classic shortcut but require the drive to be unlocked first (T2 encrypts by default):
- Shut down. Connect the two Macs with a Thunderbolt 3 (USB-C) cable.
- Power on and immediately hold the T key until a Thunderbolt symbol appears on screen.
- The drive mounts on the other Mac. If it asks for a password, enter the login password of the failing Mac to unlock FileVault.
Older Intel Macs (pre-2018)
Same hold T at startup shortcut. These may use Thunderbolt 2 or even FireWire depending on the year, so the cable matters even more — check your ports before you buy anything.
The cable is where most people get stuck
Target Disk Mode only works over Thunderbolt or FireWire — never over a plain USB-A cable, and never over Wi-Fi. Two traps to avoid:
- USB-C is not automatically Thunderbolt. Many cheap USB-C charging cables carry power only, or USB data at best. Use a cable rated for Thunderbolt 3/4 — the ones marked with a small lightning-bolt icon. A charge-only cable will do absolutely nothing.
- Mixed generations need an adapter. Connecting an old Thunderbolt 2 Mac to a new USB-C Mac requires Apple's Thunderbolt 3-to-Thunderbolt 2 adapter. FireWire-era Macs need a FireWire-to-Thunderbolt chain.
The real-world case: a Mac that boots but keeps crashing
If your Mac still reaches the desktop but freezes, kernel-panics, or restarts randomly, you have a narrow window — use it. You have two good options:
- Try Target Disk / Share Disk first. Because it bypasses macOS entirely, an unstable operating system usually can't interrupt the copy. This is the most reliable rescue for a flaky-but-not-dead Mac.
- If the drive itself is failing (you hear clicking on an old spinning drive, or files copy then error out), run Disk Utility First Aid from Recovery before you copy. First Aid can repair enough directory damage to let a stalled copy finish. Copy your most important files first — a dying drive may not survive a full clone.
Getting nowhere? Recovery Mode gives you Disk Utility, Terminal, and a Time Machine restore option even when normal boot fails.
Already have your new Mac? Skip the cable dance
If the goal is simply moving everything to a replacement Mac and the old one still boots, Migration Assistant is easier — it moves apps, accounts, and settings, not just files. Target Disk Mode is the tool for when macOS is too broken to run Migration Assistant, or when you only want to grab specific files.
When the disk won't share at all
If the Mac is completely dead — no chime, no Apple logo, no fans — it can't enter Target Disk or Share Disk Mode, because those still need the Mac to power on. In that case the drive may still be readable by a technician, or the machine may be worth more as parts. Rather than let it sit in a drawer, get a trade-in quote for a broken MacBook; we buy dead Macs for parts and put the credit toward a working one. And if you are ready to replace it, refurbished MacBooks on our Apple clearance page start at $569.99.
Frequently asked questions
Does Target Disk Mode erase anything?
No. It only mounts the drive read/write like any external disk. Your files are untouched until you choose to move or delete them.
Can I use Target Disk Mode between a Mac and a Windows PC?
Not directly — the target Mac appears as a Mac-formatted (APFS/HFS+) drive that Windows can't read natively. You need a second Mac, or third-party software on the PC.
My Apple Silicon Mac has no "T" shortcut — did Apple remove Target Disk Mode?
They renamed it. On M1/M2/M3 Macs it lives in Recovery under Utilities > Share Disk. Same idea, different path.
The shared drive is asking for a password.
That is FileVault. Enter the login password of the failing Mac (not the healthy one) to unlock and mount the drive.
What if I only care about photos and documents, not the whole disk?
Perfect — once the drive mounts, just open it in Finder and drag the folders you need. There is no requirement to clone everything, and on a failing drive you should grab the important files first.