C2D 2010 Mac Mini, startup disk partitions

[mectojic]

Hi, I've got a C2D 2.66 2010 Mac Mini Server.

I use it as a server with High Sierra, but occasionally swap to Snow Leopard for Rosetta (hence why I got this exact Mini).

Problem is, from the Startup Disk menu in System Prefs, in HS the Snow Leopard 10.6.8 option is greyed out; in Snow Leopard, no other boot option appears. The only way I can swap between the two is to restart and hold option. Problem is, I often run this Mac remotely via Screen Sharing, and you can't input option and get a boot-picker remotely.

Is there any fix for this? Or perhaps a better 3rd-party boot-picker app?

 

[Amethyst1]

Problem is, from the Startup Disk menu in System Prefs, in HS the Snow Leopard 10.6.8 option is greyed out;

Have you unlocked the control panel by clicking on the lock and authenticating? On my 2011 MBP which runs Snow Leopard, Mavericks and High Sierra, I can choose any volume from within HS after doing that.

in Snow Leopard, no other boot option appears.

Same here: only Mavericks appears as a bootable volume in SL. HS does not.

But I can force the HS volume to be booted from by running

sudo bless --mount "/Volumes/High Sierra" --setBoot

in Terminal in SL. Change the volume name to match yours. You can also force the SL volume to be booted from in HS.

 

[Wowfunhappy]

in Snow Leopard, no other boot option appears.

I have no experience, but off the top of my head, this feels like it could plausibly result from APFS.

It might be interesting to see what happens if High Sierra is installed on an HFS+ partition. IIRC that was still possible in High Sierra.

 

[Amethyst1]

[...] this feels like it could plausibly result from APFS.
It might be interesting to see what happens if High Sierra is installed on an HFS+ partition.

My HS installation is on HFS+ and it doesn't appear in SL's Startup Disk window.

 

[Wowfunhappy]

My HS installation is on HFS+ and it doesn't appear in SL's Startup Disk window.

Okay, well there goes that theory.

I do broadly wonder what's going on there, the OS's conception of what is bootable shouldn't fundamentally be changing.

 

[DeltaMac]

Just to add my own experience:
2010 21.5" iMac. Single boot drive with two boot systems - Snow Leopard, and High Sierra.
If I am booted to High Sierra, Startup Disk pane shows both SL and HS as choices.
If I am booted to Snow Leopard, then only SL shows as a choice.
That is as I would expect, as the HS drive is in an APFS container. SL is ignorant of anything APFS.
If I want to boot back into HS, then I do an Option-restart to select HS in the boot-picker window.
BUT, HS always shows both SL and HS boots in the Startup Disk pane. The only problem is when booted to SL.
Unfortunately, I don't have any helpful solutions for your need to boot between the systems. I think really all about the APFS, and Apple's need to support that newer file system.