Cannot update from Mojave on iMac Fusion Drive.

[Wilm]

I bought this new 2nd hand iMac with Mojave installed. When I try to update to Monterey there's not "enough space on the disk" available.
I did a start up from macOS Recovery. That didn't help.
What can I do?
Thanks for an answer.

 

[ptfuzi]

Usually I have the installer in an external USB, and when I run from the USB I go to terminal and do the resetfusion command

 

[Fishrrman]

I believe you need something like 65gb (that's not a typo) of "free space" for the Monterey installer to operate. It wants LOTS of space. I could be wrong.

 

[ptfuzi]

Yes the os being installed in such a small disk it's an error

 

[Wilm]

Thank you for answering.
I bought the Mac with Mojave installed on the SSD.
What I need to do now is:
- Install the Monterey update on the HHD
- Wipe the SSD with Mojave.
But in what order?
And start up in recovery mode?

Simple for an average Mac user but not for me.
Thanks for reading.

 

[ptfuzi]

I would suggest to put the installer in an USB drive, boot from that drive and from there you can erase all the partitions from both disks, or you can also re-do the fusion drive and it will erase everything for you, then you can install

 

[Fishrrman]

"What I need to do now is:
- Install the Monterey update on the HHD"

You mean... install Monterey on a platter-based hard drive?
You DO NOT want to do this.
It will run, but the performance will be awful, and the drive will thrash around.

If you're going to install and run Monterey, it should be onto an SSD.

 

[Wilm]

Thanks for answering.
But there is no space on the SSD for updating.
15,9 GB needed for update.

 

[bogdanw]

Why don't you
- create a bootable installer https://support.apple.com/en-us/HT201372
- move your data from Macintosh SSD to Macintosh HD
- make a clean install of Monterey on Macintosh SSD (See “Use the bootable installer” in the link above)
I would install Big Sur instead of Monterey, it’s more stable.

 

[Wilm]

Why don't you
- create a bootable installer https://support.apple.com/en-us/HT201372
- move your data from Macintosh SSD to Macintosh HD
- make a clean install of Monterey on Macintosh SSD (See “Use the bootable installer” in the link above)
I would install Big Sur instead of Monterey, it’s more stable.

Thank you for answering.
A friend who says he knows all about Macs is going take a look at it. I am to much of a flintstone.