Partitioning a SSD

[hughvane]

This takes some explaining, and I have looked back almost a year with Search …

I’ve been trying to get my (old) brain around the issue of safe partitioning (forgive any out-of-date terminology). Once upon a time I had the confidence to do this, and did so without bother on my old 2010 Mini (M10). All three partitions continue to work just fine, but now with the 2018 Mini I’m not so sure.

The Scenario
A 2018 Mini (M18) with MacOS Mojave [see image]. I have a continuous reminder on SysPrefs that I can update to OS Sonoma.

There are 32-bit applications on the M18 that I use repeatedly, and it is important that I retain those, but also have a second partition with Sonoma on it so I don’t necessarily have to shut down the M18 to use the M23 (see specs) because of bluetooth limitations. Instead I’d like to reboot from one partition to the other - if feasible (I do just that with the M10).

I know I can use Disk Utility to do the partitioning. Where I am hesitant is with how to preserve* what I have in the present principal partition/section of the SSD. Back in the day of spinning HDs, data was plonked randomly, and the OS had to gather it into safe harbour, as it were, before partitioning could occur without data loss.
*I have heaps of external storage, including Firewire drives.

Advice please.

 

[MacInWin]

I'm sorry, but your post is very confusing to me.

What is M18, M23, and M10? What is it you want to do? You mentioned Partitioning, but then didn't say what the desired end configuration is that you are seeking. You also mentioned specks for your machine, but only provided a screenshot of one Volume on something that might be your internal drive, or might not be, it's not clear.

So, please say what you have and what you want to end up with and maybe we can start to make some recommendations.

As a start, partitioning will generally erase the entire drive, so before you do anything, make backups of whatever you want to preserve. I think I understand you want to keep a copy of Mojave for some 32 bit applications, in which case you might think of making a clone backup of that area, wherever it is, so that it can be cloned back after any repartitioning.

And if I use the terms Container and Volume, do you know what they are? If you aren't familiar with them, we'll have to explain how APFS works so you can decide what to do. Things have changed with APFS since the old days.

 

[hughvane]

What is M18, M23, and M10?

Thank you for your input.

They are explained preceding each abbreviation, eg. M18 is Mini 2018, M10 is the Mini 2010, etc. I tend to abbreviate to reduce text content.

What is it you want to do? You mentioned Partitioning, but then didn't say what the desired end configuration is that you are seeking.

See Paras 2 & 3. I'm sorry, I should have added 'I'd like' a second partition on the M18 on which I can install Sonoma, whilst retaining what is already on the M18 (32-bit).

You also mentioned specks for your machine, but only provided a screenshot of one Volume on something that might be your internal drive, or might not be, it's not clear.

Specs are those listed under my chosen ID image. The M18, Model 8.1 is the machine under discussion. It currently has OS Mojave.

As a start, partitioning will generally erase the entire drive, so before you do anything, make backups of whatever you want to preserve.

Got it, and this may dissuade me. It is also where memory is failing me. *As I recall*, and not to be taken as fact, when I partitioned the M10 back in ~2015 when HFS was the Apple standard, the partition with the original OS Snow Leopard remained 'protected' (as it were). I was able to continue using its associated software. Then, as required, I could boot into a different partition to use more modern OS and associated software.

I think I understand you want to keep a copy of Mojave for some 32 bit applications, in which case you might think of making a clone backup of that area, wherever it is, so that it can be cloned back after any repartitioning.

Carbon Copy it? The whole of the M18 SSD is OS Mojave. As said, I have plenty of spare external storage.

And if I use the terms Container and Volume, do you know what they are?

Container no, Volume yes.

 

[MacInWin]

I'm still confused, so one more question.

Why change anything? You have a older Mac running 32 bit software just fine. Let it continue in that role. Or is there an end goal where some hardware goes away?

 

[hughvane]

Why change anything? You have a older Mac running 32 bit software just fine. Let it continue in that role. Or is there an end goal where some hardware goes away?

Valid contention.

The principal reason I wanted another partition on the M18 was to obviate the need to pull the plug of the S'sung monitor to move from the M18 to the M23 (ie. from Mojave to Sonoma). I read somewhere that it is not advisable to hot-plug an HDMI connection. At present I shut the M18 or M23 down before re-plugging and then booting either machine (one is stacked atop the other). In simple terms, it's a hassle.

The plan would have been to reboot the M18 from one OS to the other as required without pulling and replugging the monitor.

Thanks again ... Hugh

 

[MacInWin]

Does the monitor have more than one HDMI input? Or any other input besides the HDMI? It would be easiest to just cable both Macs to the monitor and then choose the input on the monitor itself, if it has two ports.

Trying to do what you want of having dual booting on one machine can be done, but is compex and fraught with lots of ways it can go wrong.

A third alternative that could be used is an HDMI switch, something like any of these:

https://www.amazon.com/s?k=hdmi+swi...p_3_8&tag=macforums0e4-20?tag=macforums0e4-20

Note that I have not actually tried ANY of them, but I did use an HDMI switch a few years ago to connecct a Mac and a Cable settop box to an older tv that had just one HDMI input. The one I had supported a remote control so that all I had to do to swap inputs was tap a button on the remote.

 

[Jimmysb]

Does the monitor have more than one HDMI input? Or any other input besides the HDMI? It would be easiest to just cable both Macs to the monitor and then choose the input on the monitor itself, if it has two ports.

Trying to do what you want of having dual booting on one machine can be done, but is compex and fraught with lots of ways it can go wrong.

A third alternative that could be used is an HDMI switch, something like any of these:

https://www.amazon.com/s?k=hdmi+switch+2+in+1+out&crid=68SRYGV3G7P3&sprefix=hdmi+swi,aps,96&ref=nb_sb_ss_ts-doa-p_3_8&tag=macforums0e4-20

Note that I have not actually tried ANY of them, but I did use an HDMI switch a few years ago to connecct a Mac and a Cable settop box to an older tv that had just one HDMI input. The one I had supported a remote control so that all I had to do to swap inputs was tap a button on the remote.

Before I retired I would have my own computer plugged in to one monitor inlet, and my work laptop plugged in to the other inlet, and like you say, switch from one to the other using the monitor input OSD.

 

[hughvane]

I'm going to give the HDMI switch another go to test the possibility there was a faulty cable, or the switch itself. It used to work with the old M10 and a previous monitor, but was quirky.

Unfortunately, whilst the newer S'sung monitor provides a high quality picture, and has two HDMI input ports, it has an awkward control system, which doesn't respond to keystrokes; and no remote (which the switch has, as can be seen).