BOOT Mac from External USB  ▷ Step by Step Guide ▷ 2020

There are times when, for some reason, your Mac computer’s operating system has stopped working (won’t start), or has serious errors that affect its daily functioning. And for this reason you cannot log in to recover important files.

To solve the errors that the system presents, start the operating system or rescue the files that you thought were lost, there is The bootable USB, this solution will allow you to have a copy of your operating system on a Pendrive or an external Hard Drive or Solid Drive.

In this tutorial we are going to explain how you can boot your MacOS computer from a bootable device and how you can create one in just a few easy steps.

Steps to start Mac computer from bootable external USB

The procedure for using a usb bootable device It is very simple, but before starting with the explanation there are a series of elements that you must have to create this great tool.

  • Device 12 GB USB (Pendrive) or an external storage disk, with the same minimum capacity specified above.

pendrive and external hard drive

  • MacOS installer, these can be macOS Mojave or macOS High Sierra, you can see how install and update Mac software from here. It may ask you to start the installation, once the download is finished, cancel this step.
  • Next, the downloaded file for no reason will you use it, just back it up in a separate folder, this copy is the one we are going to use. To create the bootable device (the method will be explained later)

These are the elements necessary for its creation, now the way to start the device is much simpler than it may be believed.

Suppose that the bootable device has already been created, now it only remains, how to start it on your computer in order to correct or repair system problems, or recover important information.

There are two methods for this, which are:

  • The first way is by using the “System preferences”, in it you will have to choose the section that says “Boot Disks”. In this menu you can select the disk that will start when you restart or turn on the computer. The only problem With this, it can only be used if you have two or more systems working correctly. (I mean your classic album, and the external unit connected and that you can access the main unit to make the configuration adjustment).

boot disk in macOS

  • If the internal system is completely inaccessibleYou have another way to boot the computer, and it is from the external disk. To do this you have to press and hold the key “Alt” during startup of your Mac computer. In this way you will get all the units currently connected to the computer to be displayed, select using the arrows on your keyboard the unit that contains the bootable operating system and press Enter to start it.

How to create a bootable installer for MacOS?

Previously we indicated a list of elements that are strictly necessary, for creating a bootable installer or bootable USB device for MacOS. Added to this, it must be added that it is necessary to carry out this procedure on a computer, without failures.

That is, the equipment you are using at the time of creating this device has to work in perfect conditions, in order to avoid failures when using the external disk or pendrive on another computer.

Steps to create a bootable disk in MacOS

These steps can be somewhat complicated, for the user who does not have much knowledge in them, but pay close attention and with care you can create it.

  • Connect the USB device to your Mac computer.
  • Wait for it to be recognized by the computer, now you just have to select the device, from the list of disk utility. And click on the delete tab (Erase) .
  • Now check that, in the format section, it is specified as follows: “Mac OS Extended (Journaling)” You will find this in the tab “Partition

USB device selection in MacOS disk utility list

  • You can modify the name just in case you want to.
  • Now you will click erase (Erase), the button in the lower right corner.
  • Wait for the device to erase itself, and restore itself to a new partition.
  • Now you are going to use the backup copy that you created of the MacOS operating system file.
  • Open the app “Disk Utility”.
  • You will have to drag the file, which you previously downloaded and made a backup copy, to the white box located to the left of the application disk utility. And automatically the disk image will be added.

disk image creation in macos

  • Now reconnect the USB device that you previously formatted. (In case of having it connected, this step is obvious).
  • Reopen the disk image window. In the disk utility application.
  • Here you will see that the operating system is already added, in the section that says “Origin” or “Source”. Now you just have to drag the device (USB drive) that was just formatted, in the section that says “Destination” or “Destination”.
  • To finish, you will click on the option “Restore” or “Restore”. Wait, I complete the procedure. This can take a long time.
  • Once the whole process is finished, you can close the disk utility application.

Check that the device works correctly

Now that the creation of the tool is completed, it only remains to check that it works correctly. For this, it will only be enough, with restarting the computer and starting from the USB device, of course, you must first configure your computer, so that it can start correctly from a Bootable USB device.

In case you haven’t already done so, you must configure it. Once you have done it, choose the corresponding options to load from an external device. If the system boots successfully, the USB device has been created successfully.

In case it doesn’t start, you just have to repeat the stepsAlways formatting the USB drive that you will use, check that it is working correctly before doing any task.

If you have any questions, leave them in the comments, we will answer you as soon as possible, and it will surely be of great help to more members of the community. Thank you! 😉

You may be interested:

Rate this post

Leave a Comment