we can move data between Macs. You can send files via AirDrop, attach them to an email message, put them in a Messages conversation, turn on and connect via File Sharing, or use Dropbox or Google Drive as an intermediary, to name just a few of the more obvious approaches.
But what if you have a lot of data—say tens or even hundreds of gigabytes—to transfer from one Mac to another? The techniques listed above might work, but we wouldn’t bet on it. If you had an external hard drive with sufficient free space handy, you could copy all the data to it from one Mac and then copy the data back off to another Mac. To cut the copy time in half, though, try Target Disk Mode instead.
What Is Target Disk Mode?
Target Disk Mode is a special boot mode that enables nearly any Mac to behave like an external hard drive for another Mac. You can connect the Macs using Thunderbolt 3, USB-C (on the MacBook), Thunderbolt 2, or FireWire. It’s best to use the same port on both Macs if possible, but it’s usually fine to use adapters, such as Apple’s Thunderbolt 3 to Thunderbolt 2 adapter for connecting newer and older Thunderbolt-capable Macs.
Target Disk Mode is nearly universal, easy to set up, and one of the fastest methods of moving files between Macs. Let’s unpack that statement:
- Nearly universal: Every Mac sold in the last decade supports Target Disk Mode, so you can be sure it will work with any modern Mac.
- Easy setup: Because Apple has baked Target Disk Mode into the Mac firmware, the version of macOS is irrelevant. There’s no software to configure nor any permissions to worry about. Putting a Mac into Target Disk Mode merely requires holding down the T key during boot or clicking a button in the Startup Disk preference pane.
- Speed: Because Target Disk Mode on modern Macs relies on a Thunderbolt connection, and you’re connecting one Mac directly to another, you’ll get the fastest transfer speeds in the fewest steps.
You can also use Target Disk Mode on an old Mac to set up a new Mac with Migration Assistant, repair its drive using Disk Utility, or possibly even boot another Mac with it. Booting one Mac from another in Target Disk Mode works best if the two Macs are of the same model and vintage and are running the same version of macOS, but it might work even if those facts aren’t true.
Step-by-Step Instructions
To use Target Disk Mode to copy data between Macs, follow these steps:
- On the source Mac, either:
- Restart the Mac, and once it starts booting, hold down the T key until you see the Target Disk Mode screen with a bouncing Thunderbolt logo.
- Open System Preferences > Startup Disk, click the lock button and enter your administrator credentials, click Target Disk Mode, and then click Restart.\
-
Connect the source Mac to the destination Mac with an appropriate cable. The source Mac’s drive appears on the destination Mac’s Desktop like an external hard drive. (If the source Mac is running macOS 10.15 Catalina, two drives will appear on the destination Mac’s Desktop: DriveName and DriveName - Data. The first is Catalina’s system volume; you’ll find all your files and folders on the Data volume.)
-
Move or copy files as desired.
-
When you’re done, press and hold the power button on the source Mac for a few seconds to shut it down.
If you have hundreds of gigabytes to transfer and either of your Macs is a notebook, it’s best to connect it to power to avoid draining the battery before the copy finishes.
Minor Gotchas
Two things can complicate putting a Mac into Target Disk Mode: FileVault and a firmware password. Both are easily worked around:
- If the Mac is encrypted with FileVault, hold down the T key at startup like normal, but then enter the administrator password for that Mac to complete the switch to Target Disk Mode.
- If the Mac has a firmware password, press the Option key while the Mac is starting up and enter the firmware password when prompted. Then press the T key to continue booting in Target Disk Mode.
Also, the Apple USB-C Charge Cable that comes with the power adapter for the MacBook, MacBook Air, and MacBook Pro models doesn’t support Target Disk Mode, so if that’s the cable you were planning to use, sorry, but you’ll need to buy a real Thunderbolt or USB-C cable.
Despite these small caveats, Target Disk Mode is one of the unsung innovations that has made Macs easier to use for decades, and it’s well worth keeping in mind whenever you need to move lots of data between machines.
AI Usage Transparency Report
Pre-AI Era · Written before widespread use of generative AI tools
AI Signal Composition
Score: 0.07 · Low AI Influence
Summary
Target Disk Mode is a special boot mode that enables Macs to behave like external hard drives for each other, allowing fast data transfer between them.
Related Posts
Leaving Flickr: Migrating 20,000+ Photos to Synology and Taking Back Control
There’s a certain kind of friction you start to notice when you’ve been using a service for a long time. Not enough to make you leave immediately, but enough to make you pause. Flickr had been that kind of service for me. It quietly held years of photos, uploads from old phones, albums I hadn’t looked at in ages, and a massive "Auto Upload" collection that had grown into something I didn’t fully understand anymore.
How I Finally Passed the PMP Exam (After 12 Years of Waiting)
Back in 2013, I registered for a PMI membership with every intention of pursuing my PMP certification. I downloaded the handbook, bookmarked the eligibility requirements, and even told a few friends that I was going to do it "soon." At the time, I thought getting certified would be a straightforward process, but little did I know what lay ahead in terms of studying and preparation.
10 Things You Didn't Know You Could Do With Apple Configurator (That Save Mac Admins Hours)
Most of us treat Apple Configurator like a fire extinguisher: break glass, DFU, restore, move on. But it can do a lot more, and when you know the edges, you can turn a bricked morning into a ship-it afternoon. Below are ten things I regularly use (or wish I’d used sooner) that demonstrate its capabilities beyond just emergency recovery.
The Evolution of Apple Certification: A Journey Through Versions, Challenges & Growth
When I recently passed the Apple Certified Support Professional (ACSP) exam again, I paused to reflect — not just on this milestone, but on the long path I’ve walked through Apple’s certification landscape. My first certification dates back to macOS 10.5, and over the years, I’ve earned credentials across nearly every version since. In that time, the exams — and Apple itself — have transformed significantly.
Secure Software, Secure Career: How I Passed the CSSLP
After passing the CISSP earlier this year, I decided to follow it up with the **Certified Secure Software Lifecycle Professional (CSSLP)** certification. For those unfamiliar, CSSLP is an ISC2 certification that focuses specifically on secure software development practices across the full SDLC—from requirements and design to coding, testing, deployment, and maintenance. My goal in pursuing this certification was to further develop my skills in ensuring the security of software throughout its entire lifecycle.
Managing Bring Your Own Device (BYOD) for Android with Microsoft Intune
Alright, so today we're going to be talking about the management of bring your own device BYOD for Android devices. There's a lot of information out there for the management of iOS devices and you can do that with pretty much any Apple MDM on the market. We just happen to use Jamf where I work, but you could use anything from Braavos to SimpleMDM to Kanji or JumpCloud. Mosyle is also a great option.
BYO with me in 2025: iOS with User Enrollment in JAMF Pro
It really depends on your company's needs. For example, many companies need to hire 1099 contractors and in such a case they come with their own devices but not the correct security settings or enforcements. Remember BYOD is a security construct. The idea here is that you should be securing the company's sensitive data in all forms. This may involve implementing policies for contractor-owned devices, ensuring that all devices accessing company data meet minimum security standards, and regularly reviewing and updating these standards to stay ahead of emerging threats.
Securing BYOD Email Access: Exploring Strategies in Microsoft 365
In today’s mobile-first world, organizations increasingly rely on Bring Your Own Device (BYOD) programs to empower employees while optimizing costs. However, this flexibility introduces unique challenges, particularly around securing email access. To mitigate risks, we are implementing a comprehensive strategy to block email access on non-company devices by default and ensure only sanctioned apps can access organizational email accounts. This approach will help prevent unauthorized access and data breaches, aligning with our commitment to maintaining the security and integrity of company communications.
How I Conquered the CISSP Exam: 9 Months, Top Resources, and Proven Strategies
Passing the CISSP (Certified Information Systems Security Professional) exam is no small feat. It’s known for its breadth, depth, and ability to test not just your knowledge but your practical understanding of cybersecurity. After nine months of intense preparation, I’m thrilled to say I’ve joined the ranks of CISSP-certified professionals! Here's a detailed account of my experience, including the resources I used, some tips that helped me along the way, and what I learned from the process itself.
Get more out of scripting than you may expect
Expect is an extension to the Tcl scripting language written by Don Libes. The program automates interactions with programs that expose a text terminal interface. Expect, originally written in 1990 for the Unix platform, has since become available for Microsoft Windows and other systems. Its functionality allows users to interact with these programs through scripted commands, eliminating the need for manual input.
