Reinstall from macOS Recovery
macOS Recovery makes it easy to reinstall the Mac operating system, even if you need to erase your startup disk first. All you need is a connection to the Internet. If a wireless network is available, you can choose it from the Wi-Fi menu in the menu bar. This menu is also available in macOS Recovery.
The videos below demonstrate the complete process of formatting an external hard drive for full Mac OS X compatibility, this uses the new Disk Utility in modern versions of OS X: Similarly, you can perform the same type of process in OS X for making a USB flash drive compatible with Mac OS using the Disk Utility in OS X, as you can see, it’s. Most of the external storage drives like portable hard drive come pre-formatted with FAT32 file system. Such FAT 32 drives can be used on both Windows and Mac OS X without any faults. But, if you wish to change the file system of the drive to other file systems like HFS + (Mac OS Extended – Journaled) then you have to reformat it from Disk Utility.
1. Start up from macOS Recovery
To start up from macOS Recovery, turn on your Mac and immediately press and hold one of the following combinations on your keyboard. Release the keys when you see an Apple logo, spinning globe, or other startup screen.
Command (⌘)-R
Reinstall the latest macOS that was installed on your Mac (recommended).
Option-⌘-R
Upgrade to the latest macOS that is compatible with your Mac.
Shift-Option-⌘-R
Reinstall the macOS that came with your Mac, or the closest version still available.
You might be prompted to enter a password, such as a firmware password or the password of a user who is an administrator of this Mac. Enter the requested password to continue.
When you see the utilities window, you have started up from macOS Recovery.
2. Decide whether to erase (format) your disk
You probably don't need to erase, unless you're selling, trading in, or giving away your Mac, or you have an issue that requires you to erase. If you need to erase before installing macOS, select Disk Utility from the Utilities window, then click Continue. Learn more about when and how to erase.
3. Install macOS
When you're ready to reinstall macOS, choose Reinstall macOS from the Utilities window. Then click Continue and follow the onscreen instructions. You will be asked to choose a disk on which to install.
- If the installer asks to unlock your disk, enter the password you use to log in to your Mac.
- If the installer doesn't see your disk, or it says that it can't install on your computer or volume, you might need to erase your disk first.
- If the installer is for a different version of macOS than you expected, learn about macOS Recovery exceptions.
Please allow installation to complete without putting your Mac to sleep or closing its lid. During installation, your Mac might restart and show a progress bar several times, and the screen might be empty for minutes at a time.
If your Mac restarts to a setup assistant, but you're selling it, trading it in, or giving it away, press Command-Q to quit the assistant without completing setup. Then click Shut Down. When the new owner starts up the Mac, they can use their own information to complete setup.
macOS Recovery exceptions
The version of macOS offered by macOS Recovery might differ in certain circumstances:
- If macOS Sierra 10.12.4 or later has never been installed on this Mac, Option-Command-R installs the macOS that came with your Mac, or the closest version still available. And Shift-Option-Command-R isn't available.
- If you erased your entire disk instead of just the startup volume on that disk, macOS Recovery might offer only the macOS that came with your Mac, or the closest version still available. You can upgrade to a later version afterward.
- If your Mac has the Apple T2 Security Chip and you never installed a macOS update, Option-Command-R installs the latest macOS that was installed on your Mac.
- If you just had your Mac logic board replaced during a repair, macOS Recovery might offer only the latest macOS that is compatible with your Mac.
If you can't get macOS Recovery to offer the installer you want, you might be able to use one of the other ways to install macOS.
Other ways to install macOS
- You can also install macOS from the App Store or Software Update preferences. If you can't install macOS Catalina, you might be able to install an earlier macOS, such as macOS Mojave, High Sierra, Sierra, El Capitan, or Yosemite.
- Or create a bootable installer disk, then use that disk to install macOS on your Mac or another Mac.
So, you just bought an external hard drive or a portable SSD and wanted to use it on your Mac. But somehow, macOS doesn’t allow you to write data to the drive.
That’s all because it’s been initialized with Windows NT File System (NTFS), which is primarily for PCs. Apple Mac machines support a different file system.
In this post, I’m going to show you how to format your external drive for a Mac compatible file system i.e. Mac OS Extended (Journaled). Just follow this easy step-by-step guide and you’re all set.
Important note: If you have useful files stored on the external drive, be sure to copy or transfer them to another safe place prior to formatting. The operation will erase all data and your files will be gone for good. You could use a recovery program like Data Rescue to retrieve them, but the odds of recovery vary.
Pro tip: If your external drive has a large volume, like mine – a 2TB Seagate Expansion. I highly recommend you also create multiple partitions. I’ll also show you how to do that below.
Most External Hard Drives Are Initiated with NTFS
During the last several years, I’ve used several removable drives, including a 500GB WD My Passport, 32GB Lexar flash drive, and a few others.
Three weeks ago, I bought a brand new 2TB Seagate Expansion to backup my MacBook Pro before I updated to the latest macOS, 10.13 High Sierra (also see those High Sierra issues I encountered).
When I connected the Seagate to my Mac, the drive icon showed up like this.
When I opened it, the default content was all there. Since I wanted to use it on Mac, I clicked the blue logo with the text “Start_Here-Mac”.
It brought me to a webpage on Seagate’s site, where it clearly indicated the drive was initially set up to work with a Windows PC. If I wanted to use it with Mac OS or Time Machine backup (which is my intent), I’ll need to format the drive for my Mac.
I then right-clicked the external drive icon on Mac desktop > Get Info. It showed this format:
Format: Windows NT File System (NTFS)
What is NTFS? I’m not going to explain here; you can read more on Wikipedia. The problem is that on macOS, you can’t work with files saved on an NTFS drive unless you use a paid app Paragon NTFS for Mac.
How to Format an External Drive to Work with Mac (from NTFS to Mac OS Extended)?
Note: The tutorial and screenshots below are based on macOS Sierra 10.12.5. They might be different if your Mac has a different version.
Step 1: Open Disk Utility.
The quickest way to do this is a simple Spotlight search (click the search icon on the upper right corner), or go to Applications > Utilities > Disk Utility.
Step 2: Highlight your external drive and click “Erase”.
Make sure your drive is connected. It should show up on the left panel under “External”. Select that disk and click the “Erase” button, the one highlighted in red in the screenshot below.
Step 3: Select “Mac OS Extended (Journaled)” in Format.
A new window will pop up asking which file system you’d like to format the external drive to. By default, it’s the Windows NT File System (NTFS). Select the one shown below.
Pro tip: If you want to use the external drive for both Mac and PC, you can also select “ExFAT”. Learn more about the differences between these file systems from this thread.
By the way, you can also rename your external drive.
Step 4: Wait until the erasing process is complete.
For me, it took less than a minute to format my 2TB Seagate Expansion.
You can also check to see if the format was successful. Right-click on the icon for your external drive on Mac desktop, then select “Get Info”. Under “Format”, you should see text like this:
Congratulations! Now your external drive has been formatted to be fully compatible with Apple MacOS, and you can edit, read, and write files to it as you want.
How to Partition an External Hard Drive on Mac
If you want to create multiple partitions on your external hard drive (in fact, you should for better file organization), here’s a step-by-step guide:
Step 1: Highlight your drive and click “Partition” in Disk Utility.
Open the Disk Utility app and highlight your external hard drive. Make sure you select the disk icon right under “External”. If you select the one below it, the Partition option will be greyed out and become unclickable.
Step 2: Add partitions and allocate volume for each one.
After clicking “Partition”, you’ll see this window. Located on the left is a big blue circle with the name of your external drive together with its volume size. What you need to do next is click the add “+” button to increase the number of partitions on your external disk. Then allocate the desired volume to each partition. You can do that by clicking the small white circle and dragging it around.
After that, you can rename each partition and define a file system for it.
Step 3: Confirm your operation.
Once you hit “Apply”, a new window pops up asking for your confirmation. Take a few seconds to read the text description to make sure it reflects what you intend to do, then click the “Partition” button to continue.
Step 4: Wait until it says “Operation successful.”
To check whether the operation is really successful, go to your Mac desktop. You should see multiple disk icons show up. I chose to create two partitions on my Seagate Expansion — one for backup, the other for personal use. You can find more info in this post: How to Backup Mac to an External Hard Drive.
That wraps up this tutorial article. I hope you find it helpful. As always, let me know if you have any issues during the formatting or partitioning process.