Adding Existing Macs to Apple Business Manager Without Wiping: The Temporary Volume Method

IMPORTANT DISCLAIMER: This procedure involves modifying disk structures and system configurations. While this method is designed to preserve existing data, there is always a risk of data loss when performing disk operations. BACKUP ALL IMPORTANT DATA BEFORE PROCEEDING. The author of this guide accept no responsibility for any data loss, system damage, or other negative consequences that may result from following these instructions. Proceed at your own risk and only if you understand the potential consequences.

Introduction

If you’re a Mac administrator, you’ve likely encountered this scenario: you have existing Mac computers in your organization that need to be enrolled in Apple Business Manager (ABM) for centralized management, but the conventional wisdom suggests that ABM enrollment requires factory-fresh devices or complete erasure.

Good news: it’s possible to add existing Macs to Apple Business Manager without wiping them. This guide walks through a step-by-step process using a temporary volume method that preserves all existing data and configurations.

Why This Matters

Adding your existing Mac fleet to ABM provides significant benefits:

• Streamlined enrollment: Automatic Device Enrollment (formerly DEP) simplifies the setup process
• Persistent management: Devices remain managed even after OS reinstallation
• Enhanced security: Management profiles can’t be removed by end users
• Centralized inventory: All organizational devices managed in one place

Prerequisites

• A Mac running macOS (works on both Intel and Apple Silicon)
• Administrator privileges on the Mac
• A COMPLETE BACKUP of your system (Time Machine, Carbon Copy Cloner, or similar solution)
• An Apple Configurator app on an iOS device
• Access to Apple Business Manager
• A Mobile Device Management (MDM) solution configured with ABM

Step-by-Step Process

Step 1: Create a Temporary Volume

Instead of wiping your entire drive, we’ll create a separate volume for a clean macOS installation:

• Open Disk Utility (Applications > Utilities)

• Select your main disk (usually “Macintosh HD”) in the sidebar

• Click the “Volume” button in the toolbar (not “Partition”)

• Click the “+” button to add a new volume

• Name it “Temp Install” and select APFS format

• Click “Size Options” and allocate at least 50GB
• Click “Add” to create the volume

Note for Apple Silicon Macs: Modern Macs use APFS containers that dynamically share space between volumes. This is more efficient than traditional partitioning.

Step 2: Boot into Recovery Mode

For Apple Silicon Macs (M1, M2, M3, M4):

• Shut down your Mac
• Press and hold the power button until “Loading startup options” appears
• Select “Options” from the menu

For Intel Macs:

• Restart your Mac
• Immediately press and hold Command (⌘) + R until the Apple logo appears

Step 3: Install macOS on the Temporary Volume

• In Recovery Mode, select “Reinstall macOS”
• Follow the prompts until you reach the disk selection screen
• Select your newly created “Temp Install” volume

• Click “Install” and wait for the process to complete
  • This typically takes approx 30 minutes despite longer initial estimates

Step 4: Boot into the Temporary Volume

The Mac should automatically restart and boot into the new volume. If not:

1. For Apple Silicon Macs:
   • Press and hold the power button until “Loading startup options” appears
   • Select “Temp Install” volume
2. For Intel Macs:
   • Restart while holding the Option key
   • Select “Temp Install” from the boot menu

Step 5: Enroll with Apple Configurator

• Launch Apple Configurator  on your iPhone.
• If you’re adding a Mac portable, plug the Mac into a power source so it doesn’t go to sleep during the process.
• If the Mac is connecting to the internet using Ethernet, plug in all necessary cables and adapters.
• Start up the Mac.
• Select the language in Setup Assistant, click Continue, then stop when you see the Country or Region pane. Note: You must restart the Mac if you go past the Country or Region pane.
• Bring your iPhone close to the Mac, then do one of the following:
  • Scan the image that appears in Setup Assistant.
  • Click Pair Manually in the lower-left corner of the Setup Assistant, then tap Manual Pairing in Apple Configurator and enter the six-digit code that appears
• Wait for the process to complete, then click Shut Down to turn off the Mac.

Step 6: Shut Down the Mac

Once enrollment is confirmed:

1. Click Apple menu > Shut Down
2. Confirm shutdown

Step 7: Assign the Mac to MDM in Apple Business Manager

1. Log in to Apple Business Manager
2. Navigate to “Devices” in the sidebar
3. Locate your newly added Mac
4. Assign it to your MDM server
   • Even if you have a default MDM, explicit assignment is required
5. Save the changes

Step 8: Verify MDM Sync

1. Log in to your MDM console
2. Manually sync with Apple Business Manager if needed
3. Verify the Mac appears in your device list
4. Confirm it shows as “assigned” or similar status

Step 9: Boot Back to Your Original System

1. Power on your Mac
2. For Apple Silicon: Press and hold power until startup options appear
3. Select your original “Macintosh HD” volume
4. Your Mac will boot to your original system with all data intact

Step 10: Complete MDM Enrollment

• Log in as an administrator

• Open Terminal

• Run this command:

• Enter your admin password when prompted

• A notification will appear about device configuration

• Click the notification details and follow on-screen prompts

Step 11: Delete the Temporary Volume

• Open Disk Utility

• Select “Temp Install” volume in the sidebar

• Click the “-” button or select “Volume” > “Delete APFS Volume”

• Confirm the deletion

• The space will be returned to your APFS container

Troubleshooting Tips

• If enrollment fails: Verify your Apple Configurator is using an account with ABM access
• If the device doesn’t appear in ABM: Wait 15 minutes and refresh; Apple’s systems can sometimes be delayed
• If MDM enrollment fails: Verify the device shows in ABM and is assigned to your MDM
• If terminal command fails: Ensure you have administrator privileges

Conclusion

This method allows you to bring your existing Mac fleet into Apple Business Manager without the disruption of wiping devices. It saves significant time and resources for IT departments while still providing the benefits of centralized management.

For organizations with a small number of Macs to enroll, this process can be scripted and documented for help desk staff, making it a viable approach even for enterprise-scale deployments.

Important Final Notes

1. Test thoroughly: Always test this procedure on a non-critical device before deploying widely
2. Have a recovery plan: Know how to restore from your backup if something goes wrong
3. Consider professional assistance: For large deployments, consider engaging with an Apple-certified IT professional
4. Risk assessment: Evaluate the criticality of each device and its data before proceeding

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Note: This process has been verified working as of macOS Ventura through macOS Sequoia. Apple could potentially change this workflow in future OS releases, but the core concept of using a temporary volume for enrollment has been reliable across multiple macOS versions.