Install Catalina on an external drive

[tomg35]

Because of 32bit apps I want to install Catalina on a external drive.

I downloaded the installer and started install, I selected all drives and then the external drive I want to use, which was already formatted. Installation started and then I was requested to reboot.

No matter what I do the computer won't boot to the external drive. Holding down the alt key doesn't work, and if I go into startup discs the drive I want to use for Catalina isn't there (I suppose it won't be because the os isn't installed yet).

How do I get installation to continue, so that Catalina ends up on my external drive?

Thanks

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[Raz0rEdge]

How as the external drive partitioned? Can you try holding Alt or Opt during bootup to get the selector? If not, if you go Sys Prefs->Startup Disk, does your external drive show?

 

[tomg35]

It's Mac is extended (journaled)

Your other points are in my original post. I don't have the T2 chip, so it's not that

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[chscag]

It's Mac is extended (journaled)

You can not install Catalina to a drive formatted to Mac extended journaled (HFS+). Reformat the external drive APFS and try again. It will then work as it should.

 

[tomg35]

I did Journaled because that's what various Mac sites said I tried the format you have suggested but still the same issue

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[chscag]

Sorry, I don't know what other problem you're running into then. However, regardless.... you can not install Catalina or Mojave to a drive formatted to HFS+. You must use APFS. There is a work around for Mojave but we do not recommend using it as it causes errors and instability.

You need to go over whatever procedure you're using. I had no problem whatsoever installing Catalina to my Samsung external SSD formatted to APFS. It boots and works as it's supposed to.

 

[Rod]

tomg35, I hope you are attempting to install Catalina onto an external SSD drive with a fast USB 3 or Thunderbolt connection because otherwise you are likely to be disappointed with performance.
While it is possible to boot and run a Mac from a HDD, USB External HD for testing purposes, as I did with Mojave in the past it will be slow to boot and run.
I would suggest that you would be better off finding updates or alternatives to your 32bit apps if possible and simply upgrade your internal drive to Catalina, BUT not yet.
If you have a browse through these forums you will see that even given ideal circumstances and preparations a lot of us have run into bugs and glitches with the current Catalina upgrade.
If I weren't into testing new software I would be waiting until the current release has been updated a few times and the bugs ironed out.

 

[tomg35]

Hi Rod,

Thanks

I have"parked" trying to do the installation for now to see what happens with the apps ( not holding much hope out as they are old and probably won't be updated).

Bit frustrating, to say the least, but that's life.

Tom

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[Rod]

I understand, you are of course welcome to list them and we will do our best to suggest 64bit alternatives that might work for you.

 

[tomg35]

Thanks Rod, very kind. Somehow I think that I will have to find alternatives

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[pm-r]

Thanks Rod, very kind. Somehow I think that I will have to find alternatives

You should certainly be able to install the new Mac OS Catalina onto an external drive, and maybe follow the procedures shown here:
macOS 10.15 Catalina Download and Install GuideAccess to this page has been denied.

When prompted, select the internal hard drive to upgrade the Mac or an external hard drive to create an external macOS drive. If you would like to wait and install Catalina at another time, cancel the installation and the Install macOS Catalina app will remain in your Applications folder.

Don't forget to have a current Working Backup - Before you start!!!



- Patrick
======

 

[tomg35]

Thanks Patrick

Despite these sites making it sound simple to do this, in my case it just doesn't work.

To begin with the external drive is seen and the process starts. Then I'm instructed to reboot and then no matter what I do the machine will only boot to the internal drive. The external drive is no longer available in start up folder.



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[chscag]

Then I'm instructed to reboot and then no matter what I do the machine will only boot to the internal drive. The external drive is no longer available in start up folder.

That sure sounds like the external drive is not bootable. Have you tried to boot from the external drive without installing Catalina? In other words, restart your Mac, and then select the external drive to boot from by holding down the option key as soon as you hear the boot sound.

If it boots to the external drive, your problems are not with the drive but elsewhere.