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User profile for user: deeptrouble
deeptrouble Author
User level: Level 1
9 points

Disk Utility Confusion

Hello,

I recently reverted back to Big Sur from Monterey, and I’m not sure Disk Utility is setup the way it’s supposed to be. The more research I do, the more confusing it becomes. Right now it seems to show (3) Drives listed for Internal, wheras I thought it should only be one, maybe 2?


1: PCI-Express Internal Physical Volume / 27.55 GB

2: APFS System Volume (System Snapshot Mounted)

3: APFS Data Volume / 1 TB


I don’t know.. not the least saavy person in the room, but this is really confusing and I just want to be certain before moving forward and potentially running into issues later.


Will someone please make sense of this, and give some advice on if I should somehow try and ‘merge’ the drives or... honestly I don’t even know. It just doesn’t look or feel right, please help.



iMac 27″ 5K, macOS 11.6

Posted on Jul 1, 2022 5:00 AM

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User profile for user: HWTech
HWTech
User level: Level 9
60,758 points

Posted on Jul 1, 2022 10:29 AM

It looks to me like you may have an iMac with a split Fusion Drive. The "ROYAL" item is a physical SSD of only 28GB which is used with a Fusion Drive setup. Your other volumes are located on a 1TB device, but the physical drive is hidden by default. You need to backup your data immediately before doing anything else just to be safe.


Within Disk Utility click "View" and select "Show All Devices" so that the physical drives appear on the left pane of Disk Utility.


You can try repairing the split Fusion Drive, but it will destroy all data on both drives.

How to fix a split Fusion Drive - Apple Support


However, it is important to know why the Fusion Drive became split. Was it your attempt to reinstall macOS or is it due to the hard drive failing? You can check the health of the hard drive by using DriveDx. Post the complete DriveDx text report here using the "Additional Text" icon which looks like a piece of paper. You may also want to post the health report for the SSD as well.


Beginning with macOS 10.15+, Apple has changed the drive layout. Here are two articles with some more information:

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


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


You should always have frequent and regular backups of your computer and all external media (including the cloud) which includes important & unique data.




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User profile for user: HWTech
HWTech
User level: Level 9
60,758 points

Jul 1, 2022 10:29 AM in response to deeptrouble

It looks to me like you may have an iMac with a split Fusion Drive. The "ROYAL" item is a physical SSD of only 28GB which is used with a Fusion Drive setup. Your other volumes are located on a 1TB device, but the physical drive is hidden by default. You need to backup your data immediately before doing anything else just to be safe.


Within Disk Utility click "View" and select "Show All Devices" so that the physical drives appear on the left pane of Disk Utility.


You can try repairing the split Fusion Drive, but it will destroy all data on both drives.

How to fix a split Fusion Drive - Apple Support


However, it is important to know why the Fusion Drive became split. Was it your attempt to reinstall macOS or is it due to the hard drive failing? You can check the health of the hard drive by using DriveDx. Post the complete DriveDx text report here using the "Additional Text" icon which looks like a piece of paper. You may also want to post the health report for the SSD as well.


Beginning with macOS 10.15+, Apple has changed the drive layout. Here are two articles with some more information:

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


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


You should always have frequent and regular backups of your computer and all external media (including the cloud) which includes important & unique data.




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User profile for user: deeptrouble
deeptrouble Author
User level: Level 1
9 points

Jul 1, 2022 3:42 PM in response to HWTech

Ah it was a while ago, but I remember one instance where I had installed Windows via Bootcamp, then removed/uninstalled Windows incorrectly. Since then..


Split Fusion Drive was something I looked into, but after downgrading all the way back to Sierra, the process of merging drives wasn’t as easy or straightforward. Then came a failed Big Sur install, which prompted the inquiry - but it eventually took, the drives were merged, and now things look as they should. Can’t thank you both enough, you guys really helped me out.


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Disk Utility Confusion

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