---
id: mac-storage-basics.what-is-a-fusion-drive
url: https://storagestudio.us/faq/mac-storage-basics/what-is-a-fusion-drive
category: "Mac storage basics"
subcategory: "Disks, APFS and formats"
question: "What is a Fusion Drive, and does it change how I manage storage?"
alt_questions:
  - "fusion drive imac"
  - "fusion drive split"
  - "is fusion drive ssd"
  - "fusion drive slow"
  - "fusion drive apfs"
short_answer: "A small SSD and a large hard drive combined into one disk on some older Macs. Manage space the usual way; an external SSD can noticeably speed up apps and projects there."
tags: ["fusion drive", "imac", "hdd"]
related: ["https://storagestudio.us/faq/mac-storage-basics/ssd-or-hard-drive-for-external-storage"]
applies_to: "all"
last_reviewed: 2026-10-01
---

# What is a Fusion Drive, and does it change how I manage storage?

A **Fusion Drive**, found in some older iMacs and Mac minis, combines a small SSD with a large hard drive and presents them as one disk; macOS keeps frequently used files on the SSD part.

Free-space advice is the same, but because most data sits on the slower hard drive, an external SSD can make a noticeable speed difference for apps and projects on these Macs. Don't split the Fusion Drive's parts unless you know exactly what you're doing.