Quick Answer
Yes, erasing the Macintosh HD drive does delete everything stored on it. The Macintosh HD drive is where macOS, your user accounts, applications, documents, settings, and all other files are stored by default. Erasing it will wipe the drive clean, removing all data stored on it. However, deleting the Macintosh HD does not touch other drives or external storage devices connected to your Mac.
What is Macintosh HD?
Macintosh HD is the name given to the primary startup drive on a Mac computer. It contains the macOS operating system, built-in applications, and any other software installed on your Mac.
When you first set up a new Mac, the Macintosh HD drive is formatted and macOS is installed on it. This drive is analogous to the C: drive on Windows computers. It is the main drive that holds the core components needed to boot up and operate your Mac.
Some key things stored on Macintosh HD include:
- The macOS system software and pre-installed Apple apps
- The Users folder containing user accounts and related files
- Applications you install
- Your documents, photos, music, downloads, desktop items, and other personal files
- System preferences and settings
- Cached and temporary files used by apps and macOS
- Security keys, passwords, and other credentials
Macintosh HD gets its name from the original Macintosh line of computers first released by Apple in 1984. The name has stuck even as Apple’s computers have evolved over the decades.
On machines running macOS 10.12 Sierra and earlier, the Macintosh HD drive was formatted using the Mac OS Extended file system. Newer macOS releases format it as APFS by default, which offers better security and performance. But the name Macintosh HD remains the same.
Does erasing Macintosh HD delete everything?
Yes, erasing the Macintosh HD drive will delete all files and folders stored on it. When you erase a drive, it is formatted to blank it out, removing all of its contents in the process.
Erasing Macintosh HD will delete:
- All your personal data including documents, photos, music, videos, downloads, desktop items, etc.
- Installed applications and related settings
- macOS system software, though it can be reinstalled
- User accounts and associated configuration files
- Any customizations or modifications made to system settings
- Cached and temporary files used by apps and macOS
- Security keys, passwords, and credentials stored on the drive
Essentially, an erased Macintosh HD will be returned to a blank state, the same as when you first purchased your Mac. The only things that will remain untouched are any other drives connected to the Mac, and any files stored on external devices like USB drives, external hard drives, network storage, etc.
Will erasing delete my personal files?
Yes, any personal files stored in your user account folders on Macintosh HD will be deleted if you erase the drive. This includes documents, music, photos, videos, downloads, desktop items, and any other files you have saved or created. Make sure to back up any important files before erasing the startup drive.
Will installed apps be deleted?
All applications and programs installed on Macintosh HD will be removed if you erase the drive. You will have to reinstall any third-party apps you need after erasing. Some apps may retain your settings and preferences if you have synced them to an online account. But locally stored app data and settings will be lost.
What about system settings and preferences?
System settings, preferences, and customizations made to macOS will be reset back to defaults if you erase Macintosh HD. This includes settings like desktop wallpaper, Safari bookmarks, keyboard shortcuts, parental controls, network configurations, and any system tweaks made through utilities like Terminal. They will all be wiped clean.
Why would you erase Macintosh HD?
There are a few common reasons why you may want or need to completely erase your Mac’s primary startup drive:
- Reinstalling macOS – Erasing the drive provides a clean slate for freshly installing macOS and apps.
- Selling or gifting your Mac – Erasing deletes all personal data to keep it secure.
- Fixing system problems – A clean install can resolve some persistent software issues.
- Removing malware – Erase to clean a malware/virus infection beyond normal removal.
- Data privacy – Deleting everything guarantees your personal files are wiped from the Mac.
Erasing the drive gives you a completely fresh and clean install of macOS. This can help resolve system problems caused by outdated caches, incompatible apps, user configuration errors, corrupted files that evade normal repair, and other issues that may persist across OS reinstalls on the existing drive.
How to Erase Macintosh HD
Here are the steps to securely erase everything on your Mac’s primary internal drive:
1. Backup your data
Before erasing, make sure to backup any important files and data you want to keep. You can backup to an external hard drive, USB flash drive, NAS (network-attached storage), or cloud storage. Use Time Machine to backup your entire system.
2. Boot into Recovery Mode
Restart your Mac and hold down Command + R as it boots up to enter Recovery Mode. This will launch the macOS recovery tools from a separate partition.
3. Launch Disk Utility
Open Disk Utility from the Utilities menu bar option in Recovery Mode. Disk Utility allows erasing, formatting, and managing connected drives.
4. Select Macintosh HD
In the sidebar of Disk Utility, select the Macintosh HD drive icon. Make absolutely sure you have the correct startup drive selected.
5. Click Erase
At the top of the Disk Utility screen, click the Erase button. This will launch the Erase options.
6. Choose Format
It’s best to use the default APFS format. This is the optimal file system for macOS. Guide Format should be Mac OS Extended (Journaled) if your Mac is using an older OS version.
7. Type a Name
You can rename the erased drive if desired. Macintosh HD is the standard name.
8. Select Scheme
Choose GUID Partition Map as the partition scheme for macOS.
9. Confirm Erase
Double check you have the correct drive selected, then click Erase to confirm and erase the drive. This will delete all data on it.
10. Exit Recovery and Reinstall macOS
When done erasing, quit Disk Utility, then reinstall a fresh copy of macOS from the Utilities menu. Your Mac will be like new again!
Alternative: Secure Erase Macintosh HD
For maximum security when deleting sensitive private data from your Mac, you can use Disk Utility’s secure erase option instead of a standard erase.
Here’s how to securely erase Macintosh HD:
- Follow steps 1-5 above to enter erase mode in Disk Utility.
- Select Security Options and choose the Most Secure 3-pass erase.
- Click OK and Confirm to securely wipe the drive.
- This will take longer but overwrite data making it unrecoverable.
- When done, reinstall macOS to use the wiped drive again.
Secure erase meets government security standards for safe data deletion. No personal information will be recoverable after overwriting the drive multiple times.
What Gets Kept When Erasing Macintosh HD?
Only data stored on the Macintosh HD drive itself gets erased when deleting that specific drive. Other connected drives and storage devices will remain untouched. Here are some things that do NOT get erased when deleting Macintosh HD:
- External USB drives, SD cards, flash drives
- Thunderbolt and USB-C external drives
- Non-startup internal hard drives and partitions
- Files stored on servers and network drives
- iCloud, Dropbox, OneDrive cloud storage files
- Time Machine and other backup drive data
- Boot Camp Windows partitions on some Macs
So you can safely erase your Mac’s main system drive without worrying about deleting other connected drives or data stored in the cloud. Just be absolutely certain to backup everything important on the startup drive itself before wiping it.
Other Startup Drive Erase Options
The above steps use the standard Erase method in Disk Utility to delete a Mac’s primary drive. Here are a couple other options:
Disk Utility’s Erase Free Space
Instead of fully erasing Macintosh HD, you can choose to only erase the free space available on the drive. This will safely delete any remaining free space where deleted files may still be recoverable. Your existing data and macOS install will remain intact.
Terminal Erase Macintosh HD
For advanced users, it’s possible to erase the Macintosh HD from the Terminal app. Use commands like diskutil erasedisk and rm -rf /* with caution to securely wipe the entire drive.
Before Erasing Macintosh HD
– Make sure you have a current backup of your important documents, photos, data, etc. Erasing deletes everything.
– If you need to preserve certain applications, back up the app installers or downloadables. You’ll have to reinstall apps after erasing.
– Verify which drive is Macintosh HD in Disk Utility before erasing to avoid deleting the wrong drive.
– If selling/gifting your Mac, sign out of iCloud and disable Find My Mac beforehand.
– Disconnect any non-startup drives like external hard drives so they are not affected.
After Erasing Macintosh HD
– You can reinstall the latest macOS from Recovery Mode after erasing.
– Restore your apps, files, and settings from backup. Some apps and services can sync data from online accounts.
– If securely erased, your data is not realistically recoverable. But the drive space can be reused.
– The Mac will operate like new after erasing. Performance may improve on an older machine.
– Double check the erased drive name matches your previous Macintosh HD name if you need it exact.
Conclusion
Erasing the Macintosh HD drive will completely delete all of its contents. This provides a clean slate to reinstall macOS and apps, resolve persistent system issues, wipe malware infections beyond normal removal, or permanently delete personal data when selling or disposing of a Mac.
Make absolutely certain to have backups of anything important before erasing Macintosh HD. The process will securely wipe the entire startup drive and return it to a like-new state. While convenient for reinstallation purposes, this also guarantees all previous user data is non-recoverable after erased. Only non-startup drives and cloud storage will remain untouched when erasing Macintosh HD.