Help setting up external boot drive for 2014 iMac

[bearmaster1]

Hello everyone. My parents have a 2014 21" iMac with the optional 1 TB fusion hard drive. The hard drive was getting slow and after upgrading to BS even slower. Lots of beachballs and all loading is slow. Rather than fussing with the internal drive, which maybe failing I thought we could get more mileage by using an external SSD.

Can you help me setup an external USB SSD for booting? This is what I think I need to do:

1 - Format external hard drive as APFS
2- Run BS installer from existing internal drive and install onto external drive
3- Boot from external USB drive and run migration assistant. We already have an active time machine backup.

Do I have this right?

 

[bearmaster1]

In case it helps anyone else, see post 2 in the link below:

Install Big Sur onto EXTERNAL SSD drive

I haven’t actually done this before, so others please feel free to correct/update me. From what I’ve read and from prior experience with older versions of MacOS, it should work, but you should be aware of a few things: Make sure you have enough bandwidth for the SSD. At minimum, use a USB...

talk.tidbits.com

 

[Fishrrman]

You should boot to INTERNET recovery.
Command OPTION R
at boot.

You'll need your wifi password if you are connecting via wifi.

When you get to the internet utilities, open disk utility.
GO TO THE VIEW MENU AND CHOOSE "SHOW ALL DEVICES" (shouting intentional)

Now erase the external SSD to "APFS with GUID partition format".

Now close d.u. and open the OS installer.
Start clicking through.
When the installer asks WHERE you wish to install, point it at the external SSD.

The Mac will reboot several times, and the screen will go dark for a few minutes. Be patient.

When done, you should see the initial startup screen (choose your language).

Begin clicking through.
When setup assistant asks if you wish to migrate from another drive, YES, you want to do this.

Point setup assistant at the INTERNAL drive, and let it go to work.
Again, be patient.

When done, you should see the login screen, booted from the external SSD.

One last thing.
Go to the startup disk preference pane and set the external SSD to be "the new boot drive".

 

[Macky-Mac]

You should boot to INTERNET recovery.
Command OPTION R
at boot.

You'll need your wifi password if you are connecting via wifi.

When you get to the internet utilities, open disk utility.
GO TO THE VIEW MENU AND CHOOSE "SHOW ALL DEVICES" (shouting intentional)

Now erase the external SSD to "APFS with GUID partition format".

Now close d.u. and open the OS installer.
Start clicking through.
When the installer asks WHERE you wish to install, point it at the external SSD.

The Mac will reboot several times, and the screen will go dark for a few minutes. Be patient.

When done, you should see the initial startup screen (choose your language).

Begin clicking through.
When setup assistant asks if you wish to migrate from another drive, YES, you want to do this.

Point setup assistant at the INTERNAL drive, and let it go to work.
Again, be patient.

When done, you should see the login screen, booted from the external SSD.

One last thing.
Go to the startup disk preference pane and set the external SSD to be "the new boot drive".

When making a bootable external drive when the internal boot drive is in good working condition, is it still necessary to install the OS on the external drive using Internet Recovery? Or can it be installed from the downloaded installer while running on the OS of the internal drive?

(A friend wants to install Catalina on an external Samsung T5)

 

[pshufd]

Hello everyone. My parents have a 2014 21" iMac with the optional 1 TB fusion hard drive. The hard drive was getting slow and after upgrading to BS even slower. Lots of beachballs and all loading is slow. Rather than fussing with the internal drive, which maybe failing I thought we could get more mileage by using an external SSD.

Can you help me setup an external USB SSD for booting? This is what I think I need to do:

1 - Format external hard drive as APFS
2- Run BS installer from existing internal drive and install onto external drive
3- Boot from external USB drive and run migration assistant. We already have an active time machine backup.

Do I have this right?

I've done this on my 2009 and 2010 iMacs though I did clean install and migrated manually. I've never used Migration Assistant.

I also have a 2014 iMac 27 and it has an i7, 500 GB SSD and 32 GB of RAM and it runs Big Sur with no problems. I have El Capitan through Big Sur installation kids on the home NAS. My process is to create a bootable flash installer from one of the kits when I do an installation. One other thing is that you can create a bootable external SSD from one system and then use it on another. I've done this too.