What about the computer name? do they both then have they same name? That’s it! Once it’s done, you can boot your target Mac into regular mode, and it should be a clone of your source Mac.Then drag the main partition of the target Mac over to the Destination area.You should see the source as the uniquely-named drive.

Since Disk Utility can sometimes load up the target Mac visibly higher or lower than the source Mac, it’s critical that you have them uniquely named (that’s why we renamed the drive earlier).

Once Disk Utility launches up, click on the main partition (the one you renamed earlier) of the source Mac. On the source Mac, select Disk Utility from the available options.Then, connect the Thunderbolt cable to both Macs.On the source Mac, reboot the computer while holding down the Cmd and R keys on the keyboard to boot into Recovery Mode.If you have done so successfully, you will see what appears to be a white lightning bolt on the screen. On the target Mac, reboot the computer while holding down the T key on the keyboard to boot it into Target Disk mode.The procedure below is for Yosemite (10.10) and earlier. More details at Cloning an image using Thunderbolt and Disk Utility (post–El Capitan) Note: If you’re using El Capitan (10.11) or later, the procedure has changed. For example, if you are imaging from 250 GB to 250 GB, that’s okay if you’re imaging from 250 GB to 500 GB, that’s also okay but if you’re imaging from 1 TB to 500 GB, that won’t work. The main hard drive partition of the source Mac must be equal to or lesser in size than the target Mac hard drive.Then, when you see the hard drive icon appear on your desktop, you can rename it. Easiest way to do this is to go to Finder > Preferences and then check or tick Hard Disks under Show these items on the desktop.

Rename the hard drive on the source Mac to something unique (don’t call it Macintosh HD, which is the default).

You can go straight from computer to computer with just a Thunderbolt cable. You don’t have to network your computer, install additional software, or have an external hard drive. Sure, you probably paid money for your Macs, but this method uses only included software… and one US$40 cable. Over Thunderbolt, cloning a roughly 30 GB (of used space) image takes only a few minutes.

Mac clone disk utility