Clone and restore SD cards on macOS

Updated August 2026 · works for any SD/USB drive, any filesystem

A full-card image is the only backup that captures everything: partition table, hidden partitions, boot flags and filesystems macOS can't even read. Before a firmware update on a retro handheld or a risky change on a Raspberry Pi card, it's ten minutes that can save your whole setup.

The terminal way: dd

Find the disk, unmount it, image it:

diskutil list                        # find the device, e.g. /dev/disk4
diskutil unmountDisk /dev/disk4
sudo dd if=/dev/rdisk4 of=~/card.img bs=4m status=progress

Restoring is the same command with if/of swapped — and triple-check the disk number: dd to the wrong device destroys it silently. Note the r in rdisk4 (the raw device — several times faster), and that on modern macOS dd needs Full Disk Access for the terminal.

Space-saving tip: clone partitions, not cards

A 128 GB card with 6 GB used still produces a 128 GB image with dd. Cloning each partition separately (or using a tool that does) keeps images as small as the data they contain, and lets you restore just the system partition while keeping your roms intact.

The one-click way

Omnimount's Clone does the same thing with a progress bar, a free-space check before it starts, automatic unmount of every partition (including FUSE mounts, which diskutil misses) and per-partition clone/restore. Same result, no disk-number roulette.

When to make an image

• Before any firmware update (ArkOS, Batocera, ROCKNIX…).
• Before repartitioning or "unhiding" anything.
• When a card starts showing read errors — image it first, repair the copy.
• After you've finally got a setup exactly how you like it.