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Disk utility showing two volumes on ssd

I'm in the process of doing a clean install of catalina. I booted from my USB install disk and erased the startup volume. When I go to install Catalina I am given a choice of two startup volumes, one a mirror image of the other. I'm attaching photos of how this looks. I'm not sure how big an issue this is but before I proceed I'd like to understand what I am looking at. Thanks.

MacBook Pro Retina

Posted on Nov 21, 2019 11:00 AM

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Posted on Nov 21, 2019 1:01 PM

I booted from my USB install disk and erased the startup volume.


It looks to be an incomplete initialization of the parent drive.


From your bootable installer> Disk Utility>View>Show All Devices> reformat the parent drive as GUID/apfs

and try again your install.


To keep the confusion down—let the installer rename the drive as it see fit. You should end up with:

Macintosh HD

Macintosh HD - Data


ex.


You can read more on the two volumes created after a successful Catalina installation.


ref: https://bombich.com/kb/ccc5/working-apfs-volume-groups

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3 replies
Question marked as Top-ranking reply

Nov 21, 2019 1:01 PM in response to marby

I booted from my USB install disk and erased the startup volume.


It looks to be an incomplete initialization of the parent drive.


From your bootable installer> Disk Utility>View>Show All Devices> reformat the parent drive as GUID/apfs

and try again your install.


To keep the confusion down—let the installer rename the drive as it see fit. You should end up with:

Macintosh HD

Macintosh HD - Data


ex.


You can read more on the two volumes created after a successful Catalina installation.


ref: https://bombich.com/kb/ccc5/working-apfs-volume-groups

Nov 21, 2019 12:47 PM in response to marby

Hi marby,


What you are seeing is normal behavior. In MacOS Catalina, Apple created a read only partition for the operating system which is sepporate from your files for security reasons. There is a second partition for your data, called Macintosh HD - Data or in your case MacBook 2014 - Data.


You can read more about it in the article about the read only partition in MacOS Catalina.


I hope this helps.

Disk utility showing two volumes on ssd

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