on Catalina - new Disk-Data appear

[Marko Zorec]

Hello....

I went to Catalina, but want to go back to Mojave.

Ok - but when I want to make clear fresh install if Mojave, when I was in Disk utility - now there is new Disk - Data appeared... Before there was just Disk and i erase it an that was it.. now I dont know what to do? Both disks“Disk” and “disk-data” have same space 121 gb but one is 1s1 other is 1s5?

 

[0128672]

In Catalina there is a read-only system volume and a data volume. Here’s more detail:

About the read-only system volume in macOS Catalina or later - Apple Support (CA)

macOS Catalina or later runs in a read-only system volume, separate from other files on your Mac. When you upgrade to macOS Catalina or later, a second volume is created, and some files may move to a Relocated Items folder.

support.apple.com

 

[Marko Zorec]

Thanks.... but how can I make only one disk again since I will use Mojave and hate two disks? Now it looks like this in disk utility on a picture - I want to have just one disk again and dont know how to do it... thanx....

 

[mikzn]

Thanks.... but how can I make only one disk again since I will use Mojave and hate two disks? Now it looks like this in disk utility on a picture - I want to have just one disk again and dont know how to do it... thanx....

Just erase the drive with Disk utilities (from an external drive) before installing Mojave, hopefully you have a back up before you erase the drive.

 

[Marko Zorec]

Backup is not a problem.

but the “disk” i cannot erase, on the other hand “disk-data” i can erase but what it does Is it is just formatting it.... dont know how to get rid off...

 

[mikzn]

You can't erase the same disk that disk utilities is running on

Use Disk Utility to erase an Intel-based Mac - Apple Support

How to erase (format) the built-in startup disk of an Intel-based Mac.

support.apple.com

 

[Marko Zorec]

I have USB with Mojave on it for clean install...... When I want to make fresh install, I turn on Mac with alt key pressed on - and then go through process - which include going to disc utility - shoul I be able to delete disc there through that exact process?

 

[mikzn]

yes if you are running the disk utility from the external drive (installer?) you can erase the drive and format as APFS - then install Mojave

- or use macOS recovery to erase the drive

If you can't start up from macOS Recovery - Apple Support

Learn what to do if you can't get your Mac to start up from macOS Recovery.

support.apple.com

 

[CoastalOR]

I have USB with Mojave on it for clean install...... When I want to make fresh install, I turn on Mac with alt key pressed on - and then go through process - which include going to disc utility - shoul I be able to delete disc there through that exact process?

Boot from the Mojave USB, launch Disk Utility, change the View (upper left button in Disk Utility) to "Show All Devices";

Then select the top Internal device (it may be named Apple something) then Erase the entire drive selecting APFS for the format. That will format the entire device to APFS. The erase will eliminate all of the volumes. Install Mojave.

 

[Marko Zorec]

Coastalor - thanx man - exactly what I was looking for...