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User profile for user: pietrowiak
pietrowiak Author
User level: Level 1
21 points

OS problem

I'm running a 1917 21,5 retina 4k imac. of an external 2tb owc nvme/envoy express with mojave os. Yesterday i decided to upgrade the 1tb fusion internal {also running mojave} to monterey. On completion i worked with monterey on the internal for a little while and everything seemed to work o.k. I then restarted to the external and i put the imac to sleep. This morning i started up and i saw on the desktop that the internal fusion drive icon had changed from macintosh hd to macintosh hd-data. Also a new disk icon named Update had appeared. I planned to restart to the internal but the internal does'nt appear in system preferences Startup Disk. What's going on. I'm flabbergasted. The internal has 88gb free and maybe this could be part of the problem?

iMac 21.5″ 4K, macOS 10.14

Posted on Sep 28, 2022 4:09 AM

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User profile for user: HWTech
HWTech
User level: Level 9
60,332 points

Posted on Sep 28, 2022 12:23 PM

Beginning with macOS 10.15 Catalina, Apple changed the drive layout by using multiple AFPS volumes for macOS. The macOS system files now reside on a read-only system volume "Macintosh HD" while user data is stored on a Data volume "Macintosh HD - Data". On macOS 10.15+ Apple does some tricks behind the scenes everything looks like it is still a single volume in the Finder (Disk Utility and the command line will reveal the truth of the new setup). However, older versions of macOS know nothing about the new drive layout so they will see separate individual volumes. Sometimes they will be mounted automatically and seen within the Finder, while other times they may not. I would be very careful using an older version of macOS to manage the APFS volumes of macOS 10.15+ except to access data on the user Data volume (do not rename this volume using an older version of macOS or things will get confusing). If you need to run First Aid on a macOS 10.15+ volume, then do so from the newer OS.


Here are two articles about some of the new drive layout changes with macOS 10.15+:

About the read-only system volume in macOS Catalina - Apple Support


Signed system volume security in iOS, iPadOS, and macOS - Apple Support



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User profile for user: HWTech
HWTech
User level: Level 9
60,332 points

Sep 28, 2022 12:23 PM in response to pietrowiak

Beginning with macOS 10.15 Catalina, Apple changed the drive layout by using multiple AFPS volumes for macOS. The macOS system files now reside on a read-only system volume "Macintosh HD" while user data is stored on a Data volume "Macintosh HD - Data". On macOS 10.15+ Apple does some tricks behind the scenes everything looks like it is still a single volume in the Finder (Disk Utility and the command line will reveal the truth of the new setup). However, older versions of macOS know nothing about the new drive layout so they will see separate individual volumes. Sometimes they will be mounted automatically and seen within the Finder, while other times they may not. I would be very careful using an older version of macOS to manage the APFS volumes of macOS 10.15+ except to access data on the user Data volume (do not rename this volume using an older version of macOS or things will get confusing). If you need to run First Aid on a macOS 10.15+ volume, then do so from the newer OS.


Here are two articles about some of the new drive layout changes with macOS 10.15+:

About the read-only system volume in macOS Catalina - Apple Support


Signed system volume security in iOS, iPadOS, and macOS - Apple Support



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OS problem

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