This is essentially the same thing dd does, except that Disk Utility can expand/contract the volume if the destination isn't exactly the same size as the source, and it's a lot faster (for some reason, dd is quite slow on OS X).ĮDIT: After seeing note about speed using /dev/rdiskN vs. it just copies the volume structures, so all the files come out identical (down to the file ID numbers). Between two Mac OS Extended volumes, this'll do a block copy, i.e. The disk structure is copied block-by-block so this dd approach works to copy data from a disk that uses a partitioning scheme that macOS doesn't natively support.ĭisk Utility can do volume-to-volume cloning with the Restore tab. Reboot your system using the Macintosh HD drive and enjoy your clone! And when we say bit-wise perfect we mean it. Now you've got a bit-wise perfect clone of your Macintosh HD drive. The last block written was a short block because there wasn't a full 1MB block to copy. That last error message is actually okay. When dd finishes you may see an error like this: dd: /dev/rdisk2: short write on character deviceĥ00107862016 bytes transferred in 14584.393113 secs (34290619 bytes/sec) Start the clone with: > sudo dd if=/dev/rdisk0 of=/dev/rdisk2 bs=1m conv=noerror,sync Let's say that Macintosh HD (disk0) is the source and Clone (disk2) is the target for our dd operation. For example: > diskutil listĢ: Apple_HFS Macintosh HD 319.2 GB disk0s2ģ: Apple_Boot Recovery HD 650.0 MB disk0s3

One of them will be your target drive you're trying to clone. Run diskutil to get a list of your available drives. With your machine booted to your secondary boot disk, log in and fire up a Terminal or iTerm window.

Otherwise you risk copying things that are in incomplete states on disk. Your source for the clone should be an offline volume, not in use, when you're making the copy. To prepare for the clone I recommend creating a secondary boot disk that you can boot from. In order to make the clone perfect you'll need to ensure the source and the destination aren't actively in use. It's a command line tool that ships with OS X. You can use the dd command to make a bit-perfect clone of a drive.

Best way to clone a mac drive