The Limits of a Single Hard Drive
Modern Macs ship with incredibly fast internal SSDs. However, video editors, 3D renderers, and professional photographers often deal with massive files where even a standard SSD becomes a bottleneck. If you need absolute maximum read/write speeds, or if you simply have multiple smaller drives that you want to combine into one massive storage volume, macOS allows you to create a RAID 0 array natively without buying expensive third-party hardware controllers.
RAID 0 (Redundant Array of Independent Disks, Level 0), also known as “Striping,” takes two or more physical drives and merges them. When your Mac writes a 10GB video file, a RAID 0 array splits the data into blocks and writes those blocks simultaneously across all the drives in the array. If you stripe two 1000MB/s drives together, your theoretical read/write speed doubles to 2000MB/s.
The Danger of RAID 0 (Important Warning)
Before proceeding, you must understand that the “0” in RAID 0 stands for zero redundancy. There is no backup mechanism in a RAID 0 array.
Because your files are striped (split) across multiple physical disks, if just one of those disks suffers a hardware failure, the data on all the other disks becomes instantly useless. The entire array fails, and all your data is permanently lost. RAID 0 should only be used for high-speed “scratch” workspaces where the source files are safely backed up elsewhere.
Step 1: Preparing Your Drives
To create a RAID array, you need at least two drives. For optimal performance, these drives should ideally be identical in make, model, capacity, and connection type (e.g., two identical Thunderbolt NVMe enclosures).
- Connect the drives to your Mac.
- Ensure there is no important data on these drives, as the RAID creation process will completely erase them.
Step 2: Using the RAID Assistant
macOS hides its RAID creation tools within the standard Disk Utility application.
- Open the Disk Utility app (found in Applications > Utilities, or by searching in Spotlight).
- In the top menu bar, click on File.
- Select RAID Assistant… from the drop-down menu.
- A new window will appear asking you to choose an array type. Select Striped (RAID 0) and click Next.
Step 3: Configuring the Array
The RAID Assistant will now ask you to configure the specific details of your new volume.
- Select Disks: You will see a list of all drives connected to your Mac. Check the boxes next to the two (or more) drives you want to combine. Pay very close attention here to ensure you do not accidentally select your internal system drive or a backup drive.
- Click Next.
- RAID Name: Give your new array a descriptive name (e.g., “HighSpeed_Scratch”). This is the name that will appear on your desktop.
- Format: Choose APFS (Apple File System) if you are running macOS 10.13 or newer. If you plan to use older Macs, choose Mac OS Extended (Journaled).
- Chunk Size: This dictates how the data is sliced. The default of 32k or 64k is generally fine for mixed usage. If you are exclusively working with massive video files, changing this to a larger size (like 128k or 256k) can improve performance.
- Click Next, and then click Create.
Step 4: Using Your New Volume
Disk Utility will unmount the selected drives, erase them, and bind them together. Once the process is complete, you will see a green checkmark.
When you close Disk Utility, you will notice that the individual drives no longer appear on your desktop or in Finder. Instead, you will see a single new drive icon bearing the name you chose (e.g., “HighSpeed_Scratch”). Its total storage capacity will be the combined total of all the drives in the array.
You can now read and write to this single volume exactly as you would any normal hard drive, but you will benefit from the massively multiplied bandwidth working behind the scenes.