- Insert a USB flash drive to your Mac. Make sure it's at least 8GB, which is usually marked on the USB stick. You can also check by right-clicking the USB drive on your desktop and clicking Get Info.
- Download the version of macOS you want to install. Unless you have a specific reason to install an older version of macOS, you can download the most recent installer from Apple.Look for the installers labeled “Combo Update” which contain the full installer.
If you want to partition your flash drive on your Mac, then you will be glad to know that it is possible. On Mac, you can do this via Disk Utility. Steps to Partition Flash Drive on Mac. Follow these instructions to partition flash drive on Mac: Step 1. On your Mac, open Disk Utility. And connect your flash drive to your Mac.
I purchased a used 2018 Mac mini desktop and wanted to put a fresh installation of the latest macOS 10.15 Catalina on it. Below are the steps I took.
Note: The instructions below are the same for macOS 10.13 High Sierra and macOS 10.14 Mojave.
Download macOS Catalina
You will need a Mac to download macOS Catalina. (The Mac mini came with macOS 10.14 Mojave so I used it to download Catalina.)
Go to the Mac App Store, search for “macOS Catalina”, and download it. It will be saved to the “/Applications/Install macOS Catalina” location. If the installer automatically launches, just close it.
Note: If you plan to run the installer first to update your current macOS version to Catalina, you will want to move the “Install macOS Catalina” application out of the “/Applications” directory; otherwise, the installer will delete itself from the “/Applications” directory when the upgrade completes. For example, you can move the “Install macOS Catalina” application to the “~/Downloads” directory and run it from there.
Format USB Flash Drive
Because macOS Catalina is 8.4GB in size, you will need a 16GB USB flash drive. You don’t need to delete the existing content on the drive because we will blow it all away in a subsequent step.
If the USB flash drive is not already formatted as “Mac OS Extended (Journaled)”, format it like so:
- Plug the USB flash drive into your Mac.
- Launch the “Disk Utility” application.
- On the left-hand pane, select the USB drive (not the partition under it, if any).
- Click on the “Erase” tab (or button at the top).
- Input a name like “Catalina” (this name will be overwritten later).
- Select “Mac OS Extended (Journaled)” for “Format”.
- If available, select “Master Boot Record” for “Scheme”.
- Click the “Erase” button at the bottom. Click the “Erase” button in the warning popup dialog if you get one.
- The format operation may take several minutes to complete. (USB 2.0 and large capacity drives may take longer.) After the format completes, the partition will be mounted under “/Volumes/Catalina” (or whatever name you selected above).
- Close the “Disk Utility” application.
Write macOS Catalina to USB Flash Drive
To create a bootable USB macOS Catalina installer, run the “Terminal” application and this command:
sudo/Applications/Install macOS Catalina.app/Contents/Resources/createinstallmedia --volume/Volumes/Catalina
# You will be prompted for your user's administrative password.
Note: If the createinstallmedia command returns a “Failed to start erase of disk due to error (-9999, 0)” error, then your current Mac OS X version does not fully support the createinstallmedia tool. Use a more recent macOS version (at least Mac OS X 10.11 El Capitan) or manually create the USB installation drive using instructions from Bootable USB Flash Drive to Install Mac OS X 10.10 Yosemite.
The “createinstallmedia” program will erase the USB flash drive, create a new partition named “Install macOS Catalina”, and copy the installation files to that partition. The output will look like:
Copying to disk: 0%... 10%... 20%... 30%... 40%... 50%... 60%... 70%... 80%... 90%... 100%
Making disk bootable...
Copying boot files...
Install media now available at '/Volumes/Install macOS Catalina'
The above process took 20-30 minutes using my Kingston USB 2.0 flash drive.
Boot From USB Flash Drive
Note: Apple’s How to create a bootable installer for macOS page suggest using the “Startup Disk” configuration (under “System Preferences”) to select the USB flash drive as the startup drive. Then on restart, the Mac should boot from the USB flash drive. Unfortunately, the “Startup Disk” did not list my USB flash drive as a startup option, so I was not able to use this method.
To boot a Mac with the USB flash drive:
- Insert the USB flash drive.
- While holding the “option” key down, turn on the Mac to display the Startup Manager.
- You should see one or more icons, one of which should be called “Install macOS Catalina” for the USB flash drive. (The internal hard drive may not be visible if it does not have a valid, bootable partition installed.)
- Note: If you don’t see the USB flash drive’s “Install macOS Catalina”, try removing and re-inserting the USB flash drive while viewing the Startup Manager screen. The USB flash drive should then appear after a few seconds.
- Select the “Install macOS Catalina” (with left/right arrow keys) and hit the “return/enter” key to boot from the USB flash drive.
It may take 5-10 minutes to load the installer from the USB flash drive. Sometimes the progress bar may appear to be frozen or the screen will go black for a minute or two. Be patient.
External Startup Disk Not Allowed
On a newer Mac with the T2 security chip, booting from an external drive may be disallowed by default. Attempting to boot from a USB flash drive will result in a “Security settings do not allow this Mac to use an external startup disk” warning message.
To allow booting from the USB flash drive, do the following:
- Hold down “Command-R” (hold down both the “Command ⌘” and “R” keys) when you start the Mac to launch macOS Recovery. You can release the keys when you see the Apple logo.
- Tip: An easier alternative is to hold the “Option/Alt” key on boot to launch the Startup Manager. Then just click and release “Command-R” keys to launch macOS Recovery.
- The macOS Recovery screen contains a top-level “macOS Utilities” menu.
- Click on the “Utilities” menu and select “Startup Security Utility”. Input your administrator password when prompted.
- In the Startup Security Utility, under “Allowed Boot Media”, select the “Allow booting from external or removable media” option.
- If the Mac won’t have access to the Internet (either by wire or wirelessly) when installing macOS Catalina, make sure to select either the “Medium Security” or “No Security” option under the “Secure Boot” section. (You can change the option back to the default “Full Security” afterwards.)
- Quit the macOS Utilities to restart the Mac.
- On restart, follow the directions in the previous section to boot from the USB flash drive.
Erase the Internal Hard Drive
When the installer finishes loading, you will see a “macOS Utilities” screen appear. It looks the same as the “macOS Recovery” screen with one difference. In the “macOS Utilities” window, the second option will say “Install macOS” instead of “Reinstall macOS”. In “macOS Recovery”, the “Reinstall macOS” option would just re-install the same version of macOS. The “Install macoS” option will install the macOS Catalina version on the USB flash drive.
Before installing macOS, I wanted a clean slate so I erased the internal hard drive like so:
- Select the “Disk Utility” option and click the “Continue” button on the bottom to launch the “Disk Utility” application.
- On the left-hand pane, select the internal hard drive (not the partition under it, if any).
- Click on the “Erase” button at the top.
- Keep the default “Macintosh HD” name or input a new one.
- Select “APFS” for “Format”.
- Click the “Erase” button at the bottom. The SSD (Solid State Drive) format took less than a minute to complete.
- Close the “Disk Utility” application.
Install macOS Catalina
Warning: If your Mac has a T2 security chip and you left the “Full Security” option configured in the Startup Security Utility, make sure that Internet access (wired or wireless) is available before starting the macOS Catalina installation. You can configure the wireless network by clicking on the wireless icon at the top-right corner of the macOS Utilities screen.
Back at the “macOS Utilities” window, do the following to start the macOS Catalina installation:
- Click on the “Install macOS” option and click the “Continue” button.
- The “macOS Catalina” installer’s splash screen will appear. Click the “Continue” button.
- Click on the “Agree” button to agree to the license. A popup confirmation window will appear; click on the popup’s “Agree” button.
- Select the internal hard drive and click the “Install” button.
My Mac mini took 20-30 minutes to complete the macOS Catalina installation. I think there were a couple of reboots in-between. And a few times, the screen would go black for a minute or two. Be patient and give the process an hour or more to complete.
If you run into problems installing macOS Catalina, check the “What Does Giving Up Mean?” section (at the bottom) of Install macOS Sierra Using Bootable USB Flash Drive for possible solutions.
Note: macOS Catalina seems to have an issue with my Dell 24in U2410 monitor. During the initial bootup screen, the monitor shows a blank screen with a message, “The current input timing is not supported by the monitor display”. Thankfully, the monitor works correctly after the bootup completes. And later, this warning message no longer appeared on bootup.
Enjoy your fresh installation of macOS 10.15 Catalina.
Oct 16, 2020 • Filed to: Solve Mac Problems • Proven solutions
For many years, users of Macs have been looking for the best tutorial to make sure that the use of USB drives on a Mac is not only explored, but it is also done well, and that the best. To help users make the best use of the system tools, this article has met the demands and needs of Mac users and increase general awareness.
Numerous advanced tips can be used to make sure that the user gets the best results when it comes to USB usage on a Mac. This tutorial will discuss the top 7 tips for using a flash drive. It will also provide a basic level of training to make the overall use of flash drive easier for Mac users.
1 Connecting Flash Drive to MAC
This is the first step that a user will take. Connecting USB to Mac is a simple process. Connecting to the Mac leads to the recognition of the device which can then be used for file transfer and sharing. USB ports are on all Macs and the user should connect the USB flash drive as seen in the picture below:
2 Formatting Flash Drive on Mac
This process is as follows:
a. Press CMD + Spacebar keys, then type application to access the application folder. Select Disk Utility.
b. Select the USB drive that is to be formatted from the left panel. Press the Erase button.
c. Press the Erase button again to confirm the process has been finished.
3 Scanning for Virus on USB Flash Drive on Mac
This is also one of the functions that should be carried out to ensure that the system is never affected and the USB drive's data is also protected properly. The USB device should be right-clicked once the ClamXav has been installed, which is the best antivirus software program. Please select the scan option to complete the process.
4 Opening Flash Drive on Mac
This is also one of the simplest processes that can be carried out. It should be noted that a user should first scan the drive for viruses so that the malware and viruses never affect the system. The finder that is built on Mac can open USB drives. The left panel shows all the connected drives and once the desired one has been clicked, the contents are shown in the right panel.
5 Transferring File from MAC to Flash Drive
Users can use flash drive on Mac in a simple way. Please scan the files that are being transferred to avoid virus attacks. The flash drive appears on the desktop of the Mac as soon as connected and the files can be dragged to finish the process.
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6 Making Backup of Your Flash Drive on Mac
Users can right-click the flash drive and select the duplicate option to backup data on Mac easily.
7 Recovering Files from Flash Drive on Mac
By using the Recoverit for Mac, the process is also very easy as below:
Recoverit for Mac can help you perform 'All-Around Recovery' once you launch Recoverit. Follow the next simple steps to perform flash drive data recovery on Mac.
Step 1: Select your flash drive on the section 'External removable device' to start scanning your data.
Step 2: A scanning process will run immediately. You can preview the files to make sure the files that you need are found.
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Step 3. Select the required files and click the Recover button to finish the process.
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