Can I create a bootable Mojave partition on an already-Catalina Mac?

[satsukikorin]

Posting this in macOS general forum since it could go validly in either/both Catalina and Mojave categories.

I have been running Catalina on my machine for many months. At the time I moved up to it, I was not aware of having any apps that were strictly 32-bit. Now, under the virus quarantine, I have pulled out an old digital audio interface device (Tascam US-1800) which the makers stopped developing before releasing a 64-bit driver upgrade. It has to run on a 32-bit-capable OS. So I am trying to set up a VM or partition or Bootcamp arrangement or SOMETHING with Mojave OS to make the device operational again.

First I tried a VMWare Mojave arrangement. That never worked. Next I tried Parallels with Mojave. That does work, and the device driver runs, and everything looks operational except that I do not actually get a signal through to the output (the meter doesn't budge; I can't hear or record any audio). So now I want to try installing Mojave directly in a disk partition, via Disk Utility, Bootcamp and/or other tools.

In Disk Utility I have created a new APFS partition with the intention of installing Mojave there. I already have the Movaje installer downloaded from the App Store on my default partition running Catalina, thanks to my earlier VM-based attempts. The installer will not open directly with a double-click, presumably because it's 32-bit ("This copy of the 'Install macOS' application is too old to be opened on this version of macOS"). How can I use it?

When I open Bootcamp, everything I see suggests that it is designed ONLY for installing or running Windows. All the online info I've found so far seems catered to that scenario too. But IRL someone has told me that actually it is possible to install and boot to Mojave via Bootcamp. Can anyone out there confirm and give instructions?

FWIW, I have a mid-2014 Macbook Pro with plenty enough space and power to support the two OS's.

 

[Fishrrman]

My advice would be to NOT try to partition a Catalina drive.

Instead, I suggest you get an EXTERNAL USB3 SSD, and then install Mojave (and the applications you need to run in 32 bits) to THAT drive.

Better to have your "alternative boot source" on a separate drive altogether.

I predict things will go much better if you do it that way.

 

[satsukikorin]

Thanks, Fishrrman. I may end up going that route, but I was really hoping to be able to do something today rather than wait for delivery of another device during virus quarantine. And that's not to mention that running real-time audio recording from or through an external device will add latency. On the other hand, maybe that's just how the cookie crumbles. :-(

Keep talking to me, internetizens. Is Fishrrman right? Are there viable alternatives?

 

[Erehy Dobon]

Like Fishrrman, I believe that partitioning drives usually causes more headaches than solving problems. Like him, I use external SSDs for booting alternate operating systems. It is FAR easier to manage it this way.

There will be plenty of people here that would say, "Oh, I do this all the time, it works for me." Great, more power to them. But for sure, your system administration load will be higher if you partition your drive.

Also, if you use an external drive, you have a bootable alternative in case your internal system drive dies.

In any case, it is wise to clone your internal boot drive to an external device, as one form of backup.

 

[satsukikorin]

Hmm, maybe my built-in SD card reader can work for this, rather than getting an external drive (ref. https://support.apple.com/en-us/HT204384). Not sure about performance, but I'll give it a whirl.

 

[Fishrrman]

A bootable SD card will work, but my guess it that it will be TOO SLOW to be useful.
Again, "the solution" is to get an external SSD and set that up to be the alternate boot drive.
Even a small SSD (128gb) will do the job, since it only needs room for the OS and apps.

 

[chrfr]

Posting this in macOS general forum since it could go validly in either/both Catalina and Mojave categories.

I have been running Catalina on my machine for many months. At the time I moved up to it, I was not aware of having any apps that were strictly 32-bit. Now, under the virus quarantine, I have pulled out an old digital audio interface device (Tascam US-1800) which the makers stopped developing before releasing a 64-bit driver upgrade. It has to run on a 32-bit-capable OS. So I am trying to set up a VM or partition or Bootcamp arrangement or SOMETHING with Mojave OS to make the device operational again.

First I tried a VMWare Mojave arrangement. That never worked. Next I tried Parallels with Mojave. That does work, and the device driver runs, and everything looks operational except that I do not actually get a signal through to the output (the meter doesn't budge; I can't hear or record any audio). So now I want to try installing Mojave directly in a disk partition, via Disk Utility, Bootcamp and/or other tools.

In Disk Utility I have created a new APFS partition with the intention of installing Mojave there. I already have the Movaje installer downloaded from the App Store on my default partition running Catalina, thanks to my earlier VM-based attempts. The installer will not open directly with a double-click, presumably because it's 32-bit ("This copy of the 'Install macOS' application is too old to be opened on this version of macOS"). How can I use it?

When I open Bootcamp, everything I see suggests that it is designed ONLY for installing or running Windows. All the online info I've found so far seems catered to that scenario too. But IRL someone has told me that actually it is possible to install and boot to Mojave via Bootcamp. Can anyone out there confirm and give instructions?

FWIW, I have a mid-2014 Macbook Pro with plenty enough space and power to support the two OS's.

You can do this without an issue. You don't actually need to partition- you can make a new APFS volume and install Mojave to it.

How to add a volume to an APFS container and why you would want to

Adding a volume to an Apple File System (APFS) container on your Mac is a pain-free process and comes with one significant benefit over traditional disk partitioning.

www.imore.com

The volumes will share storage space, and don't require you to shrink your existing Catalina installation. If you decide not to use Mojave in the future, you can just delete the Mojave APFS volume without affecting your Catalina installation whatsoever.
Bootcamp is for Windows installation, it has nothing to do with this process.
As always, and especially when doing things to your disks, be sure you have a good backup before doing any of this.

 

[satsukikorin]

You can do this without an issue. You don't actually need to partition- you can make a new APFS volume and install Mojave to it.

How to add a volume to an APFS container and why you would want to

Adding a volume to an Apple File System (APFS) container on your Mac is a pain-free process and comes with one significant benefit over traditional disk partitioning.

www.imore.com

The volumes will share storage space, and don't require you to shrink your existing Catalina installation. If you decide not to use Mojave in the future, you can just delete the Mojave APFS volume without affecting your Catalina installation whatsoever.
Bootcamp is for Windows installation, it has nothing to do with this process.
As always, and especially when doing things to your disks, be sure you have a good backup before doing any of this.

chrfr, missing from those instructions is how to install an old OS onto the created volume, and how to boot from it.

However, I've just done the proverbial forehead slap, realizing that I can probably do a Shift-Option-⌘-R startup to "Reinstall the macOS that came with your Mac, or the closest version still available" per Apple's macOS Recovery docs. I'm still a bit nervous in case Apple has decided that "still available" means something different from what one would expect. If you search the App Store for old OS versions like Mojave, you won't find them even though though they're there (you need to use special direct weblinks to access). If that doesn't count as "still available", I'd find myself installing a useless OS and then have to try to bail out of Recovery mode, which sounds like a recipe for trouble. Hmm...

In other news, I've sidestepped the whole problem by unearthing an old Macbook pro (2009, with an actual spinning hard disk!) running an OS that runs the device driver I want. So any further experimenting on my current main machine would just be For Science.

 

[chrfr]

chrfr, missing from those instructions is how to install an old OS onto the created volume, and how to boot from it.

However, I've just done the proverbial forehead slap, realizing that I can probably do a Shift-Option-⌘-R startup to "Reinstall the macOS that came with your Mac, or the closest version still available" per Apple's macOS Recovery docs. I'm still a bit nervous in case Apple has decided that "still available" means something different from what one would expect. If you search the App Store for old OS versions like Mojave, you won't find them even though though they're there (you need to use special direct weblinks to access). If that doesn't count as "still available", I'd find myself installing a useless OS and then have to try to bail out of Recovery mode, which sounds like a recipe for trouble. Hmm...

In other news, I've sidestepped the whole problem by unearthing an old Macbook pro (2009, with an actual spinning hard disk!) running an OS that runs the device driver I want. So any further experimenting on my current main machine would just be For Science.

Command-option-shift-R won't work in this case because it will download a version of macOS that's too old to use the APFS disk, so you'd need to follow one of the links for Mojave or High Sierra. (Using Google to search for "download macOS Mojave" found this page: https://support.apple.com/en-us/HT210190)
The process to install on the new APFS volume is no different than it would be if you'd partitioned the disk. You may need to make a USB install disk. Directions are here: https://support.apple.com/en-us/HT201372

 

[satsukikorin]

EDIT: Apparently I was wrong here, or at least misleadingly incomplete. See posts that follow for more information.

ORIGINAL POST:
Alright, chrfr, so your posts have been red herrings, since my thread title clearly notes "bootable Mojave". (To be clear and fair, I believe you wrote in good faith, just missed that detail.) Since these forum threads get visited over years by people trying to find solutions, I'll call out in bold for posterity: an APFS volume is not a viable approach for booting older macOS versions which didn't implement APFS. Mojave is one of those old systems.

 

[chrfr]

an APFS volume is not a viable approach for booting older macOS versions which didn't implement APFS. Mojave is one of those old systems.

No. Mojave will boot off an APFS volume without any issue whatsoever. So will High Sierra.
Apple even has a document describing these details: https://support.apple.com/en-us/HT208891

 

[satsukikorin]

You still have me lost. That's the exact document (well, the first exact document) that I've been looking at. It tells how to make an APFS volume, and instructs us to use Recovery Mode (via instructions at https://support.apple.com/en-us/HT204904) to install your old version. There's nothing in either place saying how you can hand-pick a specific macOS to install. So how do you suggest I put Mojave onto an APFS volume I create? Where would it come from?

 

[Erehy Dobon]

Since these forum threads get visited over years by people trying to find solutions, I'll call out in bold for posterity: an APFS volume is not a viable approach for booting older macOS versions which didn't implement APFS. Mojave is one of those old systems.

Since these forum threads get visited over years by people trying to find solutions, I'll call out in bold for posterity: APFS for macOS was first introduced in version 10.13 High Sierra. Support for APFS has since continued in both 10.14 Mojave and 10.15 Catalina.

I am currently running 10.14.6 Mojave on an APFS volume on two Macs: a mini 2018 and an Air 2019. Both Macs shipped with Mojave on APFS volumes.

If you'd like, you can edit your comment and strikeout the inaccuracy. Or you could leave it as is for future people to get confused.

Do you believe me now when I said that installing Mojave on a separate drive would be FAR easier?

 

[chrfr]

You still have me lost. That's the exact document (well, the first exact document) that I've been looking at. It tells how to make an APFS volume, and instructs us to use Recovery Mode (via instructions at https://support.apple.com/en-us/HT204904) to install your old version. There's nothing in either place saying how you can hand-pick a specific macOS to install. So how do you suggest I put Mojave onto an APFS volume I create? Where would it come from?

You'd need to make a bootable USB installer from the Mojave installer.
Follow this link to get the Mojave installer: https://support.apple.com/en-us/HT210190
Follow this link to make the Mojave installer into a bootable installer: https://support.apple.com/en-us/HT201372 (These are the same links I put in post 9 in the thread which you apparently didn't read.)
Once you have the bootable installer created, start your computer from it, and be sure to select the newly created APFS volume as your destination.
In your case, because your computer is older, Internet recovery will only install either Catalina or Mavericks, (and as we've covered, Mavericks cannot use an APFS volume.) Apple's directions for creating an APFS volume don't account for the scenario in which you'd be using an older computer.
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Do you believe me now when I said that installing Mojave on a separate drive would be FAR easier?

APFS volumes are really an easy way to do this sort of thing, and the process of making and using a bootable Mojave installer is the same regardless of where one installs the operating system.

 

[Erehy Dobon]

APFS volumes are really an easy way to do this sort of thing, and the process of making and using a bootable Mojave installer is the same regardless of where one installs the operating system.

I know how to make a bootable USB installer. In fact, that is the only way I do major upgrades on my Macs (yes, plural, it's easier to do two Macs from a USB installer rather than download the bits twice).

I have bootable USB flash drives (technically SDHC cards) for Catalina 10.15.3, Mojave 10.14.6 and High Sierra (whatever the last version was). I have installer files probably dating back seven versions on an external drive even though my current two Macs can't run anything earlier than Mojave.

The question was directed at the OP who seems to have had multiple issues trying to do this on the same internal disk.

I know it can be done. The point here is that it is FAR easier to just install on an external drive than diddle with APFS volumes (which I've done). I don't get my jollies spending hours upon hours with system administration tasks. The OP was struggling.

 

[avz]

I am probably too slow and missing something clever here but I am running Mojave on a APFS formatted SSD on my late 2008 MacBook without any issues. And I am even using FileVault which does not seem to slow the system down.

 

[chrfr]

I am probably too slow and missing something clever here but I am running Mojave on a APFS formatted SSD on my late 2008 MacBook without any issues. And I am even using FileVault which does not seem to slow the system down.

That's not the issue in this thread. The problem for the OP is that if they were to try to reinstall Mavericks, an APFS volume would not work because Mavericks can't recognize APFS disks.
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I know it can be done. The point here is that it is FAR easier to just install on an external drive than diddle with APFS volumes (which I've done). I don't get my jollies spending hours upon hours with system administration tasks. The OP was struggling.

There's no "diddling" involved and it seems that the OP's struggle was with getting the bootable installer. Open Disk Utility, add the volume, start up from the Mojave installer, and install onto the APFS volume. It's no more work than installing to an external drive.

 

[avz]

That's not the issue in this thread. The problem for the OP is that if they were to try to reinstall Mavericks, an APFS volume would not work because Mavericks can't recognize APFS disks.
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There's no "diddling" involved and it seems that the OP's struggle was with getting the bootable installer. Open Disk Utility, add the volume, start up from the Mojave installer, and install onto the APFS volume. It's no more work than installing to an external drive.

Makes sense. That's what I thought as well: the OP should just create a bootable Mojave installer using his Catalina installation and then boot to it, create an APFS volume in DU and then install Mojave to it, done. Ordering an external SSD for this seems like the most complicated solution. Having external backups is always a good idea though.

 

[satsukikorin]

@everyone, thanks for your input. I do appreciate you taking the time to lend your experience.

@chrfr I think I did miss your last sentence in post #9. I apologize, and you'll see that I've edited my "boldface" post #10 with strikethru and a note. There also might have been a point in my train of thought where I confused Mojave and Mavericks.

@Erehy Dobon, it's not that I didn't believe you that it's easier or better to create and use an external installer, I'm just trying to understand the alternatives and the reasons, and I got the mistaken impression that chrfr was saying it was actually possible to install directly on an APFS volume without using an external source.

For the record, I have not actually been continuing to work on this Catalina+Mojave thing for the past several days since an archeological dig in my office unearthed a 2009 Macbook Pro that already had a 32-bit-friendly OS on it. No more need for Mojave on my Catalina machine. Still, now that I have all this advice from you good people, it'd be a shame not to try putting it into practice, and I am curious about relative performance and convenience. I'll give it a try sooner or later. I don't already have an external SSD (not one available for this, anyway) and I don't care to order one during the coronavirus quarantine, so if I do it sooner, it'll be via USB. If later, maybe I'll get that extra SSD. I'll try to post back here with the results if I get there.

Thanks again.