Macintosh HD: What is It & How It Differs from Macintosh HD-Data

By Connie | Posted to Home > Wiki, updated on June 15th, 2021 |

Many Mac users find that there are two volumes in Disk Utility, one named Macintosh HD, the other called Macintosh HD - Data. In this article, we provide straightforward and informative overview to help you understand what they are and their differences.

What is Macintosh HD

From macOS 10.15 Catalina and later macOS versions, the internal hard drive of a Mac is segregated into two separate entities. One is named Macintosh HD by default.

Macintosh HD is designed to stores the operating system files and applications only, which is also called the system volume. Mac users can't erase, delete, or edit this volume. That's because Macintosh HD contains the macOS files and the Mac won't boot once these files are modified or deleted.

Macintosh HD vs. Macintosh HD - Data

Macintosh HD - Data is the other separate entity of the Mac hard drive. Though both Macintosh HD and Macintosh HD - Data are used to store data, they do different jobs.

Macintosh HD

Unlike Macintosh HD that loads system files, Macintosh HD - Data stores the Mac user data, such as documents, videos, photos, audios, etc. Mac users can edit and manage files on Macintosh HD - Data directly.

But in the Finder, both the two volumes show up as a Macintosh HD volume.

Macintosh HD shows up in Finder

Which one to erase when reinstalling or downgrading macOS?

When reinstalling macOS, you may fail due to one of the following reasons:

  1. The installer doesn't see your disk.
  2. An error message appears saying that it can't install on your computer or volume.

At this time, just as support.apple says, you need to erase your startup disk (also described as Mac hard drive or internal hard drive). That may due to the file system of the disk is corrupted or there doesn't have enough space for the upcoming operating system.

Here erasing the startup disk means that to erase the Macintosh HD volume in Disk Utility.

Note: Back up your Mac before reinstalling macOS to avoid data loss.

However, when it comes to downgrade macOS, it's a little bit different. Here erasing the startup disk contains two steps:

  • 1. Delete the Macintosh HD - Data volume.
  • 2. Erase the Macintosh HD volume.

Why should you delete the Macintosh HD - Data? Because the Macintosh HD - Data volume of the previous macOS will be retained after downgrading macOS. And system downgrading will also form a new Macintosh HD - Data volume. Then, there are two Macintosh HD - Data volumes, which may arise some problems.

More about Macintosh HD

1. If you can't find Macintosh HD on Mac, check:

  1. If your system is macOS Catalina or later or not.
  2. Whether you've renamed the system volume or not.
  3. If you've hidden the Macintosh HD volume in Finder or Disk Utility.

2. Macintosh HD volume can be repartitioned.

3. The file system of Macintosh HD is APFS or APFS (Encrypted). It can't be formatted to other file systems.

Data recovery software for Mac hard drive

Sometimes, data loss happens after you've reinstalled macOS. Without a backup, you have to get help from data recovery software.

iBoysoft Data Recovery for Mac is the most advisable Mac data recovery software. It offers full Mac data recovery that can retrieve files lost as a result of macOS reinstallation or Mac hard drive formatting. This software fully supports APFS and encrypted APFS data recovery from macOS Recovery easily.

Related posts:

How to fix Macintosh HD not mounted?

How to fix Macintosh HD greyed-out in Disk Utility?