connect mac mini with imac

I found this online.

Use more than one version of macOS on a Mac - Apple Support

looks like I can do this. the only thing confusing me is the wording on the disk utility. Is the top referring to the one I want to keep large for the Monterey (and newer) and the bottom to allot for Mojave or is it the other way around?

Not sure what the fusion drive is here. Same drive is still highlighted as it did the highlight automatically when I hit view. Or just left it there because it was already, I don't know. Nothing there says fusion.

I also need to add more context here.

Back in Sept this machine started having issues once I upgraded to Monterey. I didn't know that PS wouldn't work with it so I rolled it back. Little did I know that something was completely corrupted in there. No clue but it caused a cascade failure of ALL my content and my backup was corrupted. Maybe the drive corrupted/failed because of the backup, I don't know.

Regardless, I had this fixed. The repair guy had been used before and he's trusted. That's why there's now a 4tb drive in here instead of the 2 that it came with. unfortunately he didn't hook the microphone back up and I'm waiting on him to hook that back up. I am not bugging him to rush that - yet. I need that working at some point but it's not at the urgent level until I get the rest of this mess sorted out. Been putting things back one at a time since migration or time machine are grabbing corrupted things. He left the 120G drive in there so I can have more storage as if it's an external flash drive. I don't really see how this is going to be useful for me but it's there regardless.

I'm now getting this crap too. ugh. What is "wheel"? all the apps seem to have this. I've only installed two apps since getting it back so it's kinda "naked". I cannot change any of those permissions.

I want to "partition" the 4tb drive and my confusion is still the same from the post above...

looks like I can do this. the only thing confusing me is the wording on

the disk utility. Is the top referring to the one I want to keep large

for the Monterey (and newer) and the bottom to allot for Mojave or is it

the other way around?

Well it's done. It got late and I was done with this imac for the night. IΩΩmage below. You can answer later today if you have only your phone and don't want to be annoyed.

I have to do more but I also have appointments today. Photoshop goes in later when I get home.

What I found is that once I got Mojave installed I had this come up on the screen while it was installing. If I can strip all the apps out of there that I don't need I certainly would! I miss the old days of "Mac v Windows" where you build up what apps / programs YOU want on them instead of them acting like Windows and coming preloaded with crap I simply don't use or need. Things would be so much less bloated.

Anyway, I'm going run it for a bit and see how it goes. IF what's in the images attached causes me issues, I am 99% sure I am going to have to reverse it and wipe the drives and do it opposite and then assign the Monterey to be the start up. I have a feeling that's what I should have done but figured keeping the apps I put in and use would be staying put except PS. cross your fingers.

Ugh... ok so then how about this...

I have a 4tb drive in this beast. Can I split the drive (fusion drive) and allot the one split 1tb of space for running Mojave and the rest can be used regularly and update the OS safely when updates are required?

I have the link saved from when Apple helped me do it, BUT right after is when the cascade fail started. What she didn't say is that you can allot specific amounts of space for each one, hence my question on which one is the one to give less to... the top (reserve) or bottom (quota)?

I was going to upgrade what I'm using now and put the Mojave on the partition. I would only need it for photoshop so loading up as my main drive should be Monterey. I'm not ready for Ventura. I like to let a year go by, sometimes less when a new OS comes out so the bugs can be worked out.

Thank you for your help, you have no idea how much appreciated this is.

ha one step ahead of you here. backed up since my last post and am installing Monterey now. If it all goes I can wipe it out and start fresh.

FYI - allocating a size to reserve as I asked about is useless. It will only do 2/2 or 1/1 etc. Seems you can't do otherwise so I just left it blank

[Edited by Moderator]