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Monkton

macrumors newbie
Original poster
Oct 19, 2019
3
0
I'm thinking of doing a clean install of macOS Mojave on an external SSD drive.

What's the procedure? Do I have to reformat the drive?
 

Mr_Brightside_@

macrumors 68040
Sep 23, 2005
3,530
1,736
Toronto
If you want it clean, then yes. Wipe it to APFS, download Mojave, then point the installer at the SSD and let it do its thing.
 

Monkton

macrumors newbie
Original poster
Oct 19, 2019
3
0
OK, first, "Wipe it to APFS" – the options I get on trying to erase are:
– Mac OS Extended (Journaled)
– Mac OS Extended (Case-sensitive, Journaled)
– MS-DOS (FAT)
– ExFAT
Which is right?

Next, "download Mojave" – where from? It's not available in Apple Store.
 

Mr_Brightside_@

macrumors 68040
Sep 23, 2005
3,530
1,736
Toronto
OK, first, "Wipe it to APFS" – the options I get on trying to erase are:
– Mac OS Extended (Journaled)
– Mac OS Extended (Case-sensitive, Journaled)
– MS-DOS (FAT)
– ExFAT
Which is right?

Next, "download Mojave" – where from? It's not available in Apple Store.
– Mac OS Extended (Journaled). It should be converted to APFS during install.
 
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Fishrrman

macrumors Core
Feb 20, 2009
22,640
8,518
Axeman -

Try this (read carefully).

First, prepare your external USB drive.
Erase it to Mac OS extended with journaling enabled, GUID partition format.
Let it be for the moment (connected, but not doing anything).

Now, turn your attention to getting your Mac booted to "the right recovery mode".
I believe you want to power down, ALL THE WAY OFF.
Now, reboot and IMMEDIATELY hold down the following key combination and KEEP HOLDING IT DOWN for a while:

Shift-command-OPTION-R

(yes, I realize it's a "finger contortion")
What this should do is boot you into a recovery mode that will install the version of the Mac OS that came pre-installed on your Mac.
Hopefully, this was NOT Catalina.

IMPORTANT:
Of course, you DO NOT want to install this to your internal drive.

So....

Begin the install procedure, but watch carefully for the moment the installer gives you the option to "show all disks".

NOW you want to "point the installer" towards your USB drive, so that the OS install will go onto it.

Are you able to do this?
If so, go through with the install.

When the install is done, you should now be booted to the USB drive (in Mojave).
Go through a basic setup, get it set up the way you want.

That's how I'd try to do it.
 
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