Running Mac OS from a USB or external drive

helgansven

Hi All, my first post!

I have two older (2016), 15" Macbook Pro devices with Monterey as the OS.

Is it possible to make an image of device#1 and run that image from a USB or external drive on device#2?

I've tried a couple tutorials online but no love (likely me not understanding instructions).  After imaging 500GB stick from device#1 and attempting to boot from it on device#2, I can select the USB device from the startup options screen but the OS on the USB will not boot.

Basically, it goes:

1. Format USB as Mac OS Extended (Journaled) + GUID Partition.

2. Create Monterey bootable USB installer (sudo /Applications/Install\ macOS\ Monterey.app/Contents/Resources/createinstallmedia --volume /Volumes/500GBDrive)

3. Clone internal drive to USB (using Carbon Copy with changes only being cloned).

4. Attempt boot from USB on device#2.

For some more detail, when I boot device#2, I hold the option key till I see the boot device selection screen.  The USB is seen by the device and is shown as a separate icon on screen.  After selecting the 500GBDrive, the device will only show a black screen with a circled "X" and an address for what I'm assuming is Apple's official "how to boot" page.

I'm know I'm doing something wrong, but can't seem to see it.  Am I trying to do something that's not possible (or frowned upon)?

marvin

helgansven said:

Hi All, my first post!

I have two older (2016), 15" Macbook Pro devices with Monterey as the OS.

Is it possible to make an image of device#1 and run that image from a USB or external drive on device#2?

I've tried a couple tutorials online but no love (likely me not understanding instructions).  After imaging 500GB stick from device#1 and attempting to boot from it on device#2, I can select the USB device from the startup options screen but the OS on the USB will not boot.

Basically, it goes:

1. Format USB as Mac OS Extended (Journaled) + GUID Partition.

2. Create Monterey bootable USB installer (sudo /Applications/Install\ macOS\ Monterey.app/Contents/Resources/createinstallmedia --volume /Volumes/500GBDrive)

3. Clone internal drive to USB (using Carbon Copy with changes only being cloned).

4. Attempt boot from USB on device#2.

For some more detail, when I boot device#2, I hold the option key till I see the boot device selection screen.  The USB is seen by the device and is shown as a separate icon on screen.  After selecting the 500GBDrive, the device will only show a black screen with a circled "X" and an address for what I'm assuming is Apple's official "how to boot" page.

I'm know I'm doing something wrong, but can't seem to see it.  Am I trying to do something that's not possible (or frowned upon)?

This seems mostly right but Apple locked the bootable systems down more with recent Mac systems.

Carbon Copy Cloner has some guides for how to make a bootable drive:

https://bombich.com/kb/ccc6/help-my-clone-wont-boot
https://bombich.com/kb/ccc6/cloning-macos-system-volumes-apple-software-restore

"If I continue to make regular backups to the destination, will it remain bootable?

You should not expect the destination to remain bootable after running additional backup tasks to the destination (i.e. via manual or scheduled backups). The Legacy Bootable Copy Assistant is intended only for creating ad hoc, bootable copies of the system that you intend to use immediately."

Carbon Copy Cloner recommends making a dedicated external bootable volume without backups in the same place. Try to get a bootable system volume first without doing any data backups. Then try multiple partitions on the same drive or a separate drive for data (latter will be more reliable).

Another thing you could try is booting an older system before Big Sur and then upgrading the system while booted into it.

edited December 2023

helgansven

Thanks Marvin, those are good ideas.

I'll look more into CCC to see if I can get it working.

I've also got a much older Mac with Mountain Lion installed.  I can give it a try there too.  That's a long road of upgrades from there to Monterey.  But what have I got to lose by trying right?

Thanks again!