How do I install Big Sur on USB drive?

[Mork]

I know how to get a bootable USB installer. That's fine.

However, for a backup program like ChronoSync to do bootable backups, Big Sur actually needs to be installed on that USB drive. I can't figure out how to do that. If I start the Big Sur installer, it looks like it wants to install on my Mac regardless of where I start the installer from.

Can someone help point me in the right direction?

Thx.

 

[myfranco]

It's so easy. Make sure you disable SIP first and let the computer to boot from USB drive. Download Big Sur from App Store and choose your USB drive to install. It will boot from USB after restart. If it doesn't choose USB BigSur as your startup drive. I just did it yesterday. Mac mini 2018 Big Sur

 

[chrfr]

It's so easy. Make sure you disable SIP first and let the computer to boot from USB drive.

It's unnecessary to turn off SIP but if the computer has a T2 chip it is necessary to set it to allow booting from external drives.

About Startup Security Utility on a Mac with the Apple T2 Security Chip - Apple Support

Use Startup Security Utility to make sure that your Mac always starts up from your designated startup disk, and always from a legitimate, trusted operating system.

support.apple.com

 

[myfranco]

It's unnecessary to turn off SIP but if the computer has a T2 chip it is necessary to set it to allow booting from external drives.

About Startup Security Utility on a Mac with the Apple T2 Security Chip - Apple Support

Use Startup Security Utility to make sure that your Mac always starts up from your designated startup disk, and always from a legitimate, trusted operating system.

support.apple.com

Mini 2018 has T2 chip. I had to. Since poster didn't mention his/her conf, I just mentioned just in case.

 

[chrfr]

Mini 2018 has T2 chip. I had to. Since poster didn't mention his/her conf, I just mentioned just in case.

SIP can stay enabled when enabling booting from external drives.

 

[Mork]

Sorry for the confusion here. My question was how to make the USB drive 'bootable' in the first place. I downloaded the Big Sur installer file, but how do I run it ON the USB drive? Thanks.

 

[chrfr]

Sorry for the confusion here. My question was how to make the USB drive 'bootable' in the first place. I downloaded the Big Sur installer file, but how do I run it ON the USB drive? Thanks.

Here are some good directions: https://www.macworld.co.uk/how-to/macos-external-drive-3659666/

 

[chabig]

The answer is in post #2. Run the installer. It will ask you where you want Big Sur installed. You tell it to install Big Sur on the USB drive.

 

[Mork]

Thanks very much.

I may just do the backup on a regular USB drive and then use the Data Migration Wizard rather than going through the extra hassle to create a bootable backup. Supposedly Apple will (may) make bootable disk backups easier sometime, eventually, maybe.