Feb 03, 2020 Fusion Drive, a storage option on some iMac and Mac mini computers, combines a hard drive and flash storage in a single volume for improved performance and storage capacity. If your Fusion Drive appears as two drives instead of one in the Finder, it's no longer working as a Fusion Drive. The Fusion Drive comes as standard with the following iMacs: 21.5-inch, 4.1GHz Processor, 1TB Fusion Drive: £1,449; Retina 5K, 27-inch, 4.1GHz Processor, 1TB Fusion. Oct 07, 2019 Select your hard drive in the Disk Utility window. It will be the first drive on the list. It might be named 'Fusion,' or 'Macintosh HD.' Click on the Partition tab. You will be prompted to either add an APFS volume or a Partition. Click Partition. Hhere is the same with an MacMini from 2014. Mojave works, but the update to Catalina fails. After repairing the volume, I installed Yosemite and after that upgraded to Catalina. But after the next upgrade to Catalina the fusion drive is broken again. To get the system working, I restored the whole system from TimeMachine.
For years, early adopters and beta testers would partition their Mac's hard drive in order to test a new or beta version of macOS. Partitioning your hard drive actually creates a separate container on your hard drive that is limited in its abilities.
If your Mac uses APFS, you can actually create a volume right on your current hard drive instead. This allows your hard drive to manipulate your available storage temporarily as you need it. It makes testing new or beta operating systems much easier to do and easier to remove when you're done testing them out.
IMPORTANT: The developer beta of Big Sur is currently experiencing some issues with installing and updating versions including and most importantly, installing Big Sur onto separate volumes.
From Apple's developer support notes for Dev beta 2:
You might be unable to install macOS Big Sur 11 beta onto additional volumes. (63677460, 64445236)
![Catalina Catalina](/uploads/1/2/7/1/127125569/133133143.jpg)
If macOS Big Sur 11 beta is installed into the same APFS container as previous versions of macOS, system software updates can no longer be installed on the previous versions of macOS. (64411484)
If you are installing the developer beta of macOS Big Sur, we highly recommend going with partitioning your hard drive not creating a volume.
Before you start
The most important thing to do before making any changes to your hard drive is to back it up. Seriously. Back it up. Please. Time Machine is the easiest way to back up your data if you don't already have another system in place.
Second, make sure you have enough free disk space to properly run a secondary operating system. Shoot for at least 30GB free, though I recommend closer to 50GB if you have it available.
What's the difference between a disk partition and a volume?
A partition and a volume act in very similar ways, but creating a volume allows for flexibility of storage needs while creating a partition separates storage with a specific amount and does not adjust for each drive's needs.
What is a partition?
Partitioning your Mac is basically splitting your hard drive into separate, usable systems. It makes it possible to run two separate operating systems on one device, like Windows and macOS, or two versions of macOS (like Catalina and Big Sur).
Note: If you want to run Windows on your Mac, Apple's Boot Camp assistant will automatically make a partition for you. Here's how to install Windows.
![Download mac os catalina Download mac os catalina](/uploads/1/2/7/1/127125569/563161448.jpg)
It is important to note that partitioning your hard drive also splits up your available hard drive space. Each partition will take up a portion of your usable storage. So, if you are running low on storage capacity on your hard drive, we don't recommend partitioning.
If you are running a Mac using HFS+ file system (prior to macOS Catalina) you must partition your hard drive. If your Mac uses APFS, Apple recommends creating a volume instead.
What is an APFS volume?
An APFS volume creates a similar container to be used the same way as a partition, but it mounts it within your main hard drive. This allows the volume the flexibility to grow or shrink in storage size as needed. You don't have to worry about running out of temporary space while installing macOS, for example, because it will grab the necessary space from your main drive and then put it back when it's done. You can manually select size limiters for a volume if you're worried about one drive overtaking another's space.
If your Mac uses APFS, Apple recommends creating a volume instead of a partition.
How to add an APFS volume on Mac
You can test the beta of Big Sur on your Mac without having to change anything on your daily driver by creating a volume that acts as a separate drive so you can install a completely different operating system. This allows you to switch between OSes using the Startup Disk option.
- Open Finder from your Mac's dock.
- Select Applications.Source: iMore
- Scroll down and open the Utilities folder.
- Double-click on Disk Utilities to open it.Source: iMore
- Select your APFS drive (Should be called Macintosh HD) from the sidebar.
- Enter a name for the volume.Source: iMore
- Select the type of APFS format you want. I recommend just APFS.
- Click Add.Source: iMore
You have the option of selecting a specific size that you want the volume to be, which will guarantee this volume will always have the reserve size you want. However, APFS volumes are designed to allocate disk space as needed. If you're worried about running out of disk space on either your main drive or the new volume, you can select a minimum/maximum volume size. After completing Step 7 above:
- Click Size Options.
- Enter a Reserve size to ensure that the new volume will always have a minimum amount of space.
- Enter a Quota size to ensure your main drive never runs out of space.Source: iMore
- Click OK.
- Click Add.Source: iMore
How to create a partition on your Mac
- Open Finder from your dock.
- Select Applications.Source: iMore Reinstall macos fusion drive.
- Scroll down and open the Utilities folder.
- Double-click to open Disk Utility.Source: iMore
- Select your hard drive in the Disk Utility window. It will be the first drive on the list. It might be named 'Fusion,' or 'Macintosh HD.'
- Click on the Partition tab. You will be prompted to either add an APFS volume or a Partition.
- Click Partition.
- Click the Add partition button it looks like a plus (+) symbol.
- Change the size of the partition you wish to use by dragging the resize controls. The used space is represented in blue.
- Name the new partition.
- Specify which file system format you want to use. If you're running macOS 10.13 or higher, you'll want APFS. If you are running macOS 10.12 or older, you'll want Mac OS Extended.
- Click apply.
Disk Utility will check the disk and make changes. This will take several minutes.
How to switch partitions or volumes
You can switch to the new partition, install the current macOS, and then download and install macOS Catalina from there.
- Click the Apple icon in the upper-left corner of your screen.
- Select System Preferences from the drop-down menu.
- Select Startup Disk.
- Click the Lock in the lower left corner of the window to unlock and make changes.
- Enter your system admin password.
- Click OK.
- Select your partition drive.
- Click Restart.
You can also restart your Mac and press the Option Key when you hear the startup chime. This will take you to the Startup Manager and you can select your drive from there.
You will then be asked to install macOS. This will install the latest available macOS onto the partitioned hard drive. You may have to install an older version of macOS before updating it to the more recent version you want to run.
If you are testing a beta version of macOS, you'll first install whatever the current version is. Then, you can then install the macOS beta.
How to download the beta of macOS Big Sur
Install Mac Os Catalina
Once you've updated your partitioned Mac with macOS Catalina, you can download and install the beta of macOS Big Sur. For the developer beta, you need a developer account and some patience. Developer betas are often a bit complicated to install. We've got a guide to help you out.
Any questions?
Do you have any questions about installing a partition or downloading a new operating system onto a partitioned drive? Let us know in the comments. If you're having trouble partitioning your hard drive, be sure to check out our forums for help!
Updated June 2020: Updated for the developer beta of macOS Big Sur.
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Fusion Drive, a storage option on some iMac and Mac mini computers, combines a hard drive and flash storage in a single volume for improved performance and storage capacity. If your Fusion Drive appears as two drives instead of one in the Finder, it's no longer working as a Fusion Drive. This can happen after replacing either drive of your Fusion Drive or using software to intentionally split them into separate volumes.
You can continue using the two drives independently or follow these steps to regain the benefits of having the single logical volume of a Fusion Drive.
Before you begin
If you're not sure that your Mac was configured with a Fusion Drive, or that the drive has been split:
- Disconnect any external storage devices from your Mac.
- Choose Apple menu > About This Mac, then click Storage.
- If you see a drive labelled Fusion Drive, your Fusion Drive is working and this article doesn't apply to you.
- If you have a Fusion Drive that has been split, you should see two drives. One of them should be labelled Flash Storage, with a capacity of 24GB, 32GB or 128GB. The other should be at least 1TB.
Use Terminal to create a Fusion Drive again
These steps permanently delete all data stored on the drives that make up your Fusion Drive. Make sure that you have a backup before continuing.
If you're using macOS Mojave or later
- Turn on your Mac, then immediately press and hold Command-R to start up from macOS Recovery. Release the keys when you see the Apple logo or spinning globe.
- When you see the macOS Utilities window, choose Utilities > Terminal from the menu bar.
- Type
diskutil resetFusion
in the Terminal window, then press Return. - Type
Yes
(with a capital Y) when prompted, then press Return. - When Terminal indicates that the operation was successful, quit Terminal to return to the macOS Utilities window.
- Choose Reinstall macOS, then follow the onscreen instructions to reinstall the Mac operating system. Your Mac restarts from your Fusion Drive when done.
If you're using macOS High Sierra or earlier
- Turn on your Mac, then immediately press and hold Command-R to start up from macOS Recovery. Release the keys you see the Apple logo or spinning globe.
- When you see the macOS Utilities window, choose Utilities > Terminal from the menu bar.
- Type
diskutil list
in the Terminal window, then press Return. - Terminal displays a table of data about your drives. In the IDENTIFIER column, find the identifier for each of the two internal, physical drives that make up your Fusion Drive. Usually the identifiers are disk0 and disk1. One of them should be 128GB or less in size. The other at least 1TB in size.
- Type the following command, replacing identifier1 and identifier2 with the identifiers you found in the previous step. Then press Return.Example: diskutil cs create Macintosh HD disk0 disk1
- If you get a disk unmounting error, enter
diskutil unmountDisk identifier
, using the first identifier you gathered previously. Then enter same command again using the second identifier. Then retry the command in step 5. - Type
diskutil cs list
, then press Return. - Terminal displays additional data about your drives (volumes). Find the string of numbers that appears after ”Logical Volume Group” for the volume named Macintosh HD. It's a number like 8354AFC3-BF97-4589-A407-25453FD2815A.
Example:
+-- Logical Volume Group 8354AFC3-BF97-4589-A407-25453FD2815A
|
| Name: Macintosh HD - Type the following command, replacing logicalvolumegroup with the number you found in the previous step. Then press Return.Example: diskutil cs createVolume 8354AFC3-BF97-4589-A407-25453FD2815A jhfs+ Macintosh HD 100%
- When Terminal indicates that the operation was successful, quit Terminal to return to the macOS Utilities window.
- Choose Reinstall macOS, then follow the onscreen instructions to reinstall the Mac operating system. Your Mac restarts from your Fusion Drive when done.