cancelled macOS Monterey update takes up storage

Part 1 of 3

1 - Check in the Applications folder a new Application called "Install Monterey "

If it exists, Drag and Drop to Trash and Empty the Trash

Part 2 of 3

2 - " I've tried to remove system junk using CleanMyMac " which is sometime referred to " BrickMyMac "

Any Third Party Applications that will interfere with the normal operation of the OS,  is an invitation for disaster and comprise the Operating System

Certain Applications maybe available on the Apple Apps Store - this only means the Developer is prepared to pay Apple a portion on each sale. What the Application may do to the computer is up to the User to check this out before purchase

Any of the below should be removed as per Developers Instructions 

This will include CleanMyMac

Read some of the posting and arrive at your own conclusions.

Part 3 of 3

Rebuild the Spotlight index on your Mac

What is “Other” storage on a Mac, and how can I clean it out?

Free up storage space on your Mac

OmniDiskSweeper Safe to use

GrandPerspective 

How to delete Time Machine snapshots on your Mac

See used and available storage space on your Mac

Locate backups of your iPhone, iPad, and iPod touch

The final word from Apple on Managing the " Other/ System Data “ Category

Other / System Data: Contains files that don’t fall into the categories listed here. This category primarily includes files and data used by the system, such as log files, caches, VM files, and other runtime system resources. Also included are temporary files, fonts, app support files, and plug-ins. You can't manage the contents of this category. The contents are managed by macOS, and the category varies in size depending on the current state of your Mac.

The system data was once called the Other Category:

he Other category is a potpourri of files which can include:

• System temporary files

• macOS system folders

• Archives and disk images (.zip, .iso, etc. - often found in the Downloads folder)

• Personal user data

• Files from the user’s library (Application Support, iCloud files, screensavers, etc.)

• Cache files: browser, Mail

• Mail messages & attachments

• Fonts, plugins, extensions

• Safari reading list

• iTunes backups

• Crud resulting from jailbreaking your iDevice

• Game data

• Saved data files

• Call history

• Notes

• Media

• Voice memos

• Other files that are not recognized by a Spotlight search

• Media files that cannot be classified by Spotlight as a media file because they are located inside of a package

• Files created and modified by other user accounts on your Mac.

They can be located anywhere on your hard drive.

The files that you have control over are located in the Documents, Downloads, Pictures, Music and Movies folders.  You can use this free app, GrandPerspective, to find the largest files on your drive so you can determine if they can be deleted or moved to an external HD for storage.

Note: you can empty the Downloads folder after the apps and/or updates that were downloaded have been installed or applied.  Some users have found a couple of Gigabytes of files in their Downloads folder which are no longer needed. 

NOTE: you school strive to keep about 80 - 100 GB of free space for optimal system and application performance.

henriette99 wrote:

Ok, so the 12 GB from "Install Monterey" will be available after some time?

Yes it will

Is there a way I can reduce these 79 GB of system data? A why does finder and the DiskSight scan only show about 10 GB of system data?

How many upGrades has this computer experienced in the lifetime of this computer.

Each time the computer has been upGraded to a newer version of macOS - elements of the old may stay behind

The accumulated effects of several upGrades will eventually show up and present this type of issue

As has been mentioned by @Old Toad and self plus Apple - the User ( you ) have zero control over this Category

" You can't manage the contents of this category.

Thanks!

There is a Major difference between " Purgeable Space " and " Empty Space "

Purgeable Space is Managed by the Operating System ( not the User ).

Giving about a day ( 24 Hrs ) or so, some of the purgeable space will be marked by the Operating System ( not the User ) as Empty Space .

CleanMyMac is considered by many of the more experienced users in these forums to be akin to malware. Uninstall it according to the developer's instructionsl.

I am guessing this computer may have the tiny 128GB Internal Drive ?

If that is correct, There maybe a way but it will require a drastic method

➡️ ➡️ The below is not to entered into would careful consideration & really understanding that will happen ⬅️ ⬅️

Scorched Earth Method 

This method will WIPE ALL Data and there is No Recovery of any Data - Period.

>> Only works on Intel Based Apple Computer <<

To perform this action will require booting from a Bootable Installer. 

The Bootable Installer can Only be performed on an Apple Computer 

This will have to be performed from a Qualifying Computer to run the version of macOS to be made on the Bootable Installer.

Example : Bootable Installer of Monterey would have to be done on a computer that Qualifies to run Monterey.

Notation: If the computer being used to perform this action is Too New or Too Old to qualify to run the version of macOS - this computer can not be used.

Alternative is, to gain access to a Qualifying Apple Computer from a family member, friend or associate.

Extra Special Notation regarding the Touch ID equipped Apple Computer.

 About Startup Security Utility and Must Enable from Recovery Mode the ability to boot from External Drive Before Attempting 

1 - Shutdown computer and disconnect all external drive Except the newly created Bootable Installer.

2- Restart and immediately hold the OPTION key until the Startup Manager appears and choose the USB Drive. 

3 - It will present options >> Disk Utilities >> View >> View ALL attached Drives. 

4 - Choose the Upper Most Drive ( not the volumes indented and list below ).

5 - The drive normally is called Apple Media or Apple SSD - that is the drive to Erase and format as APFS with the GUID Partition Map.

6 - Once that is done >> backup out of Disk Utilities and choose install macOS. 

7 - Follow the prompts and it may automatically reboot several time. 

8 - Upon a final reboot - Setup Assist will present with the newer version of macOS.