A Free Way to Duplicate or Clone USB on Mac with Multiple Partitions

4 min readFeb 29, 2024

Unlike direct file copy from USB drive, disk clone is a whole different tasks, which keeps all the information as the same as the original USB drive. This especially difficult on a Mac as there are dozens of disk clone software available for Windows 11.

The Benefits of Cloning a USB Drive

Cloning a USB drive offers several benefits, particularly in terms of data management and backup. When you clone a USB drive, you create an exact replica of its contents, including the bootable operating system (if applicable), applications, and data files. This process is invaluable for creating backup copies of critical data. Cloning can also be a lifesaver for recovering from malware attacks or accidental deletions.

Furthermore, cloning is beneficial for deploying multiple computers in environments like schools, offices, or labs, where uniformity in software and system settings is required. By cloning a USB drive that contains a pre-configured system setup, administrators can efficiently distribute the same operating system, applications, and settings across multiple computers, saving time and ensuring consistency. This is particularly useful for quickly setting up workstations with the same software configurations or for upgrading multiple computers to a new operating system version without manually installing the OS and applications on each machine.

How to Clone a USB Drive on Mac with Multiple Partitions

Cloning a USB drive with multiple partitions on a Mac using the dd command is a powerful technique, as dd creates a bit-by-bit copy of the drive, ensuring that all partitions and their contents are replicated exactly. However, this process requires caution due to the potential risk of overwriting important data if the wrong drive is specified. Here’s a step-by-step guide:

Note: Disk Utility is not working for disk clone!

Step 1: Identify the USB Drive

First, you need to identify the USB drive’s device identifier in the system. You can do this by opening the Terminal app and typing the following command:

diskutil list external

Look for your USB drive in the list, identified typically by its size and name, and note its identifier, which will be something like /dev/disk2. I will use this disk identifier in my case.

Step 2: Unmount the USB Drive

Before cloning, you must unmount the USB drive to ensure that no data is being written to or read from it during the cloning process. Do not eject the drive; just unmount it using the following command:

diskutil unmountDisk /dev/disk2

Step 3: Backup the USB Drive to .img File

Now, use the dd command to clone the USB drive. You will need a destination drive with enough space to hold the entire contents of the source USB drive. The command format is:

sudo dd if=/dev/disk2 of=/path/to/destination/file.img bs=1m

if= specifies the input file (your source USB drive).
of= specifies the output file (this can be a path to a disk image file you wish to create).
bs=1m sets the block size to 1 megabyte for faster copying.

Replace /path/to/destination/file.dmg with the desired path and name for your disk image.

Step 4: Wait for the Process to Complete

The dd command does not provide progress feedback, so the process may appear to hang, especially for large drives. Be patient and wait for it to complete. The time it takes will depend on the size of the USB drive and the speed of your Mac and the drives.

Tip: You can use the key combination (control + t) to see the instant process of dd command.

Step 5: Clone the .img File to Another USB drive

Once the cloning is complete, you can now restore the image file to the target USB drive as many as you can.

sudo dd if=/path/to/file.img of=/dev/diskN

/dev/diskN is the disk name of target USB drive.

You will be able to enter a new command when the clone is completed successfully.

Bonus: Clone Multiple USB Drives at Once on Windows PC without dd

dd command is free and comes with macOS. However, there is no progress bar indicating the cloning task. In addition, the writing speed of dd command is very slow. In fact, this USB cloning process could be done much easier on a Windows PC.

Simply copy the .img file to Windows PC via external drive (formatted by exFAT) and download the free PassMark ImageUSB tool.

https://www.osforensics.com/tools/write-usb-images.html

Choose the USB drive to be cloned and import the .img file. Click the Start button and you will see a progress bar for monitoring the copying task.