Build Your Own Fusion Drive

Introduction

Fusion Drive for Mac gives you the best of both worlds: super fast workflow and speed, thanks to the SSD (Solid State Drive) and high-capacity storage space on the traditional hard drive. Apple sells the Fusion drive as a $799 option with the new Mac Mini and iMac.

In this tutorial we will look at building and creating our own Fusion Drive for much cheaper rates that gives the same performance as Apple’s Fusion Drive.

Getting Started

To build a Fusion Drive you need to use terminal. Though I will be listing out all the commands needed to make it possible for you to build your Fusion Drive, I should warn you that Terminal does not have a Graphical User Interface (GUI) and spellings are important to get right.

To create a Fusion Drive, you will need three sets of storage drives:

• A hard drive and
• An external drive to backup to – creating a Fusion volume will erase both the SSD and the hard drive, so if you have information on the hard drive you want to keep, you’ll need to have a copy of that data elsewhere. This is optional and if you are just setting up your mac you wouldn’t be needing an extra drive to backup to.
• An SSD installed/to install. It is possible to build a Fusion Drive through an internal or externally connectedd SSD. Though the recommended method is using an internal drive because if you accidentally remove the SSD – the Fusion Drive would not function and will crash. In this tutorial we will be looking at building a Fusion Drive through an internally connected SSD. Nonetheless, the process and commands are the same for an externally connected SSD, so you can always follow these steps.

1. Organise Your Drives

We need to two drives for a Fusion Drive. In this tutorial we will look at the Hitachi 1TB 2.5-inch hard drive (the one that ships in a Mac mini) and the 240GB OWC Mercury Extreme Pro 6G SSD.

Apple chooses the drives based on extensive testing which is the reason why they do not recommend creating your own Fusion Drives.

2. Clone Your Data

If you have any data that you would like to keep from any of these two drives, this is the time to back it up. The process (CoreStorage) to build a Fusion Drive will erase all data from the drives.

Have a look at our foolproof guide for creating a backup system for your Mac if you need help with backing up.

3. Start Up Terminal

The Disk utility application that comes with every OS X does not support the creation of Fusion Drives. Though we will be using the Disk utility , we will be looking at the command line version of the application that has more features.

You can’t boot into a drive you want to use as part of the fusion drive if that’s the case then you will need to go into recovery mode and use terminal from there. The CoreStorage process that is used to “fuse” the drives also will format them and you can’t do that to a drive you are booted to.

Boot into recovery mode by clicking and holding command+R, immediately after the start-ip chime, when starting up your Mac.

4. Lets Build it!

Now that we have terminal open and our booted into recovery mode, we can start building the drive.

List the drives your system can see by entering the following command:

diskutil list

This will list the drives for you to see like this:

The drive mounts are labelled as /dev/disk# . Note down the drives you want to fuse.

In my mac /dev/disk0 is the boot disk and /dev/disk1 & /dev/disk2 are the drives that I will fuse. An easy way to tell which is the SSD and which is the Hard drive is by the sizes indicated. Make sure you dont confuse the names as there isn’t a warning before terminal will erase them forever.

Create a logical Volume Group. Now lets create a CoreStorage Logical Volume Group that will have the pool that we will use as the Storage space for our drive.
To do this use the following command:

diskutil coreStorage create nameYourThing drive1 drive2

Now combine the drives /dev/disk1  and /dev/disk2 by typing:

diskutil coreStorage create myLogicalVolGroup /dev/disk1 /dev/disk2

When the process is complete your Logical Volume Group should have been successfully completed and Terminal will present you with a Unique Identifier for the group which should look like this. You should also copy this to your clipboard.

Create the Logical Volume. Now that we have the Logical Volume Group, we can create the logical volume that the Mac will recognize as a Single Drive.
Type the following command to create the logical Volume:

diskutil coreStorage createVolume lvgUUID type name size

• lvgUUID is the unique identifier you copied from the previous step.
• type use Journaled HFS+ (typed as jhfs+ ).
• name  can be whatever you want to name the drive (traditionally “Macintosh HD” is used and I recommend it as its the name used in many other tutorials online). Make sure you use quotes if there’s a space in the name.
• size is how much of the “pool” that you want to make into a drive, using the following suffixes: B(ytes), S(512-byte-blocks), K(ilobytes), M(egabytes), G(igabytes), T(erabytes), P(etabytes), or (%) a percentage of the current size of the logical volume group.

In my example , I typed the following Command:

diskutil coreStorage createVolume 50B457C3-ADC6-4EDC-9ABA-FD8C6EEDE69A jhfs+ "Macintosh HD" 100%

After you type your own command , the Fusion Drive would be created successfully using up 100% of the pool and will be named “Macintosh HD”

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