Creating the Bootable Drive You need an external drive to turn into a bootable version, and since it needs to be portable, your best choice is a USB thumb drive with a capacity of 16GB or more. 2 days ago Some Mac users may wish to create a bootable MacOS Catalina installer drive, typically using a USB flash drive or with another similar small boot disk. Bootable USB installers offer an easy way to upgrade multiple Macs to macOS Catalina, to perform clean installs of MacOS Catalina, to perform maintenance from a boot disk like formatting disks. Luckily, making a bootable installation of the Mac operating system became a whole lot easier when Apple launched OS X Mavericks back in 2013. With that version of Mac OS X, and all versions since. Jun 27, 2019 A macOS Catalina USB install drive is a great tool to have on hand to for quick and easy macOS 10.15 reinstalls. We show you how in this video tutorial. Jan 15, 2014 Insert your USB into the Mac and run the Disk Utility. Select the USB drive that appears in the left-hand menu and select the Partition tab across the top. Select the drop down menu and click on 1 partition. In the format type menu make sure you have Mac OS Extended (Journaled) selected. The macOS Mojave installer software is just over 6GB, so you need a USB external drive that can hold that much data. The drive can be a thumb drive, hard drive, or SSD. If you want to use a thumb.
Creating A Bootable Usb Drive Mac Os X El Capitan
By default, Mac starts from its built-in hard disk, but a startup disk can be any storage device that contains bootable contents that compatible with your Mac. For example, if you install macOS or Microsoft Windows on a USB drive, your Mac can recognize that drive as a startup disk. This guide provides 2 ways to boot a Mac from a USB flash drive.
Requirement
Starting up your Mac from an external disk requires the following:
- Intel-based Mac.
- Bootable USB thumb drive formatted with a GUID partition type and containing an OS X installer or a usable operating system.
Let’s see how to boot a Mac from a bootable USB drive and what to do if your Mac doesn’t start up from it.
Way 1: Boot Mac from USB Drive using Startup Manager
Getting your Mac to load from a USB drive is fairly straightforward. Use the following steps, you can easily set Mac boot from an external drive in Startup Manager, so it’ll only boot from USB that one time.
Step 1: Insert the USB boot media into a USB slot.
Step 2: Turn on your Mac (or Restart your Mac if it’s already on).
Step 3: Press and hold the Option key immediately after you see the Apple logo. Holding that key gives you access to OS X’s Startup Manager. Once the Startup Manager screen appears, release the Option key. The utility will look for any available drives that include bootable content.
Step 4: Using either the pointer or arrow keys on the keyboard, select the USB drive you wish to boot from. Once selected, either hit the Return key or double-click your selection. The machine will start to boot from the USB drive.
Way 2: Set a Mac Boot from USB Drive using Startup Disk
When you use Startup Disk preferences to set Mac boot from an external drive, so it’ll boot from that disk until you choose a different one. Here is how:
Step 1: Go to Apple menu > System Preference, then click Startup Disk.
Step 2: Click the locked icon and then enter your administrator password.
Step 3: Select External drive as the startup disk, then restart your Mac.
What to do if your Mac does not boot from the selected drive
If you see a message prompts that your security settings do not allow this Mac to use an external startup disk, check the External Boot setting in Startup Security Utility, and then allow your Mac to use an external startup disk.
Step 1: Open Startup Security Utility.
Turn on your Mac, then press and hold Command (⌘) + R immediately after you see the Apple logo. Your Mac starts up from macOS Recovery. When you see the macOS utility window, choose Utilities > Startup Security Utility from the menu bar. When you’re asked to authenticate, click Enter macOS Password, then choose an administrator account and enter its password.
Step 2: Select “Allow booting from external media“.
If you want to select an external startup disk before restarting your Mac, quit Startup Security Utility, then choose Apple menu > Startup Disk.
Note: If you’re using Boot Camp in a dual-boot Windows/OS X environment, you may be unable to boot negatively into supported versions of Microsoft Windows XP, Windows Vista or Windows 10 operating systems installed on external USB hard drive.
Make sure disk has been formatted with a GUID partition type
Intel-based Macs support starting from an external USB storage device’s volume that has been formatted with a GUID partition type. If you wish to boot from the drive, it’s important to format the partition as “GUID Partition Table” rather than either of the other two ahead of time when you use that drive as a bootable drive.
Make sure your disk is bootable
Volumes that aren’t bootable and don’t contain a copy of a valid operating system aren’t listed in Startup Disk or Startup Manager. Make sure the external drive you’re trying to start from contains a usable operating system.
If you have more than one Mac you want to upgrade to macOS 10.15 Catalina but don't want to waste so much bandwidth downloading it for each machine, one option is to create a bootable installer on a spare USB flash drive. Here's how to do it with the Terminal.
One of the problems with the release of a major operating system update like macOS Catalina is the amount of times it has to be downloaded. As Apple usually intends each Mac or MacBook needing to be updated to download it, the process isn't really efficient enough for instances where many Mac desktops need the upgrade, like in a school or business if there isn't device management or macOS Content Caching for whatever the reason.
The strain could also be felt by users who own multiple Macs but also have a limited data allowance from their Internet provider, or a small amount of bandwidth that could make updating multiple machines take a very long time and saturate the available connection.
While in the olden days it was possible to get the software update on physical media, Apple doesn't offer that option anymore. However, it is still possible to create your own media, such as a spare USB thumb drive, that can do the same job.
The first hurdle is to actually get the macOS Catalina installer onto a Mac. This is an unavoidable part of the process and will require just over 8 gigabytes of drive capacity to store.
Go to the Mac App Store and search for Catalina using the search bar, then click on View next to the macOS Catalina listing. Alternately, open the Mac App Store Preview page for macOS Catalina here then select View in Mac App Store.
Click on Get. This will load up the Software Update utility, which will ask if you want to download macOS Catalina. Click Download.
After the download has finished, macOS will automatically start the installer. Press Command-Q to quit the installer before it continues, as the update will be deleted upon installation.
Creating the Bootable Drive
You need an external drive to turn into a bootable version, and since it needs to be portable, your best choice is a USB thumb drive with a capacity of 16GB or more. Be aware that the drive will be wiped as part of the process, so ensure there isn't any precious data on the drive that could be lost if it isn't backed up elsewhere.
Connect the external drive to your Mac, and make a note of the external drive's name as it appears within macOS. This is important, as using the wrong name could lead to another connected drive being wiped by mistake.
Open Terminal within the Utilities folder within the Applications folder and enter in the following command by copying and pasting it directly into the window. Make sure to change the element titled 'USBdrive' for the name of the drive you intend to become the bootable installer.
sudo /Applications/Install macOS Catalina.app/Contents/Resources/createinstallmedia — volume /Volumes/USBdrive — /Applications/Install macOS Catalina.app
Once pasted and corrected, press enter, then enter your password for macOS and press enter again.
Terminal will then warn of the USB drive being wiped as part of the process. Type 'Y' and press enter. Leave the Mac alone as it formats and copies over the installer.
Once Terminal says 'Install media now available,' it is safe to right-click the removable drive on the desktop renamed 'Install macOS Catalina' and select the 'Eject' command. It is now safe to remove the drive from the Mac.
Upgrading another Mac
Before proceeding, ensure there are adequate backups available for the Mac you are about to upgrade before the process starts.
With the target Mac you want to upgrade turned off, connect your external drive. When turning on the Mac, hold down the Option key on the connected keyboard to bring up the Startup Manager.
The Startup Manager is used to boot from a different drive from the default. In this case, select 'Install macOS Catalina.'
The Mac will then bring up a macOS Utilities window. To perform a straight update, select 'Install macOS' and follow the prompts.
The macOS Utilities menu also allows you to erase the Mac's drive, which you can optionally do if you do not wish to save any of the data and want a completely clean slate for the installation.
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