Catalina and Mojave in 2 volumes on an internal SSD

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Catalina and Mojave in 2 volumes on an internal SSD

I´m still running Mojave 10.14.6 on a 2018 iMac, and don´t want to abandon Mojave just yet until I´ve played around and tinkered with Catalina. My idea is as follows:

Create a new volume (not a partition) on my internal 500 GB SSD.

Install Catalina on it.

Then move, not copy, all my data (docs, Photos Libraries etc.) to the new Catalina volume.

On the Mojave volume I would leave nothing but the System and Photoshop CS6. I depend on Photoshop for my daily work, and I know it doesn´t work in Catalina. Thus my idea of splitting my internal SSD into 2 volumes. I know I could also keep a Mojave clone on an external SSD and boot from that when I need to use Photoshop.

Needless to say I shall be making clones and TM backups of my Mojave setup before I start on this!

Is creating a new volume a good idea? Or would booting from a Mojave clone be better? Any help/suggestions gratefully received! Regards, Ian.

iMac 27" 5K, macOS 10.14

Posted on Dec 30, 2019 9:59 AM

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Answer 1

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Soren Pearson

Level 4

1,339 points

Dec 30, 2019 3:04 PM in response to Ian Leckie

Hi Ian,

As you said, always make a backup/clone before doing this in case anything happens.

What I did on my Mac was create a a second partition and installed Catalina on that. I currently have a dual boot system one with Mojave as my main system and the second partition with Catalina as I still rely on 32 bit applications that will never be made into 64 bit as the company has stopped development or went out of business.

What I did was go into Disk Utility and created a second partition for Catalina. Then I downloaded Catalina from the Mac App Store and selected the second partition for installation.

I hope this helps.

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Answer 2

Ian Leckie Author

Level 4

2,262 points

Dec 31, 2019 6:20 AM in response to Soren Pearson

Thanks for replying, Soren! When I finally get around to Catalina I think I´ll first do what HWTech has posted. That seems to me to be the safest (and simplest) option...you´re braver than I am! Best wishes for 2020! Regards, Ian.

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Answer 3

Ian Leckie Author

Level 4

2,262 points

Dec 31, 2019 6:24 AM in response to HWTech

Thanks for replying, HWTech! Yes, I have a gut feeling that installing multiple operating systems on a single drive could lead to problems, which I really don't need at the moment! I have several new external Samsung SSDs, so I´ll be doing what you suggest...seems to me to be the "non-destructive" solution. Best wishes for 2020! Regards, Ian.

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Answer 4

HWTech

Level 9

60,086 points

Dec 30, 2019 6:25 PM in response to Ian Leckie

A much safer option is to install Catalina onto an external USB3 or Thunderbolt drive. Trying to install multiple operating systems on a single drive usually leads to problems.

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Answer 5

Dec 31, 2019 7:35 AM in response to Ian Leckie

Hi Ian,

My pleasure, I'm glad I could help. I do agree with HWTech as well to install on an external drive if you want to play it safe.

Happy new year to you and best wishes as well!

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Catalina and Mojave in 2 volumes on an internal SSD

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