Catalina and Mojave dual boot: Should Mojave be on a volume in a container or on its own partition?

[pullman]

I have Catalina as the main OS and today installed Mojave on a volume within the container that also holds the Catalina volume. EDIT: I also have Monterey in a volume on that same container.

When I boot into Mojave I get "Incompatible Disk. This disk uses features that are not supported on this version of MacOS".

Is this because I put Mojave in the same container as Catalina or Monterey?

In other words, should I instead have put Mojave on a partition? If so, should it be formatted HFS+?

I'm still a bit bewildered by APFS so thank you in advance for your help
Philip

 

[Fishrrman]

My advice is to NOT have both OS's on a single drive, partitioned or not.

If you want to run both, buy a cheap 2.5" SSD (128gb will do fine, some of these sell for $20), put it into a USB3 external enclosure, and install the OS onto that.

Now boot each OS (on each drive) completely "independent of" the other one.

Less trouble !

 

[pullman]

Thank you for the reply. Just so I understand, could you explain a little bit more what could become the problem?

My advice is to NOT have both OS's on a single drive, partitioned or not.

If you want to run both, buy a cheap 2.5" SSD (128gb will do fine, some of these sell for $20), put it into a USB3 external enclosure, and install the OS onto that.

Now boot each OS (on each drive) completely "independent of" the other one.

Less trouble !

 

[KeesMacPro]

could you explain a little bit more what could become the problem?

Mojave and newer use an APFS format.
However, there has been a development within APFS, short: Mojave= generation1 , Catalina= gen.2 etc
So if you e.g. format a drive booted in Catalina and install Mojave, the format will have features that are newer than the OS installed > incompatibility issue.
As recommended in post #2 , I'd not install multiple OSes on the same physical drive to begin with.
Just to avoid lots of headaches with partitions (theoretically viable option) and containers.

To set this up, I would:
- use separate drives for different OSes
-first format all drives when booted in Mojave,now when running the installer of the desired OS you can format to the corresponding APFS gen. (if not automatically done by the installer).

To put it in other words: an OS doesnt "understand" a newer APFS gen (and will never run on it) , but will recognize an older version.

 

[ondioline]

However, there has been a development within APFS, short: Mojave= generation1 , Catalina= gen.2 etc

No. APFS has been version 2 since High Sierra. There is literally no problem making an APFS container in Catalina or newer and installing Mojave.

 

[KeesMacPro]

There is literally no problem making an APFS container in Catalina or newer and installing Mojave.

Did you read this somewhere or did you test it?

APFS has been version 2 since High Sierra

That doesnt make much sense , since APFS was introduced with HS...

 

[pullman]

Thanks for your replies.

Apple itself says it is possible to multi-boot like this, which presumably means that it ought not cause trouble, but I just know that when I had Catalina, Mojave and Monterey installed within one and the same container on my MacBook Air I got the error I mentioned.

 

[ondioline]

Did you read this somewhere or did you test it?

I'm curious, have you done any research at all. APFS was present in later Sierra patches, everything after that was version 2. There have been no changes in compatibility beyond that.

 

[ondioline]

installed within one and the same container

It has to be another container obviously.

 

[KeesMacPro]

I'm curious, have you done any research at all. APFS was present in later Sierra patches, everything after that was version 2. There have been no changes in compatibility beyond that.

You may sit down and take a look here :

starting at post# 239 (with a clear explanation for noobs in post #247 as a bonus):

Latebloom - An experimental workaround for the 11.3+ race condition

Use separate disks for Mojave and Big Sur. Doing the way you want is sure way to data corruption in the long run. APFS evolved a lot since Mojave.

forums.macrumors.com

starting at post #8670:

OpenCore on the Mac Pro

This don't make sense, if you update the APFS driver at the start of the APFS partition it will be incompatible with Mojave itself. Remove your Mojave disk from your Mac Pro, install you Mojave fail safe disk only when needed. Backup any APFS data disks formatted by HighSierra/Mojave/Catalina...

forums.macrumors.com

starting at post #1957:

MP5,1: What you have to do to upgrade to Mojave (BootROM upgrade instructions thread)

Nope, Mojave can't even open a Big Sur APFS disk.

forums.macrumors.com

I could go on for a while listing links with empirical data from reliable sources , if only I'd be willing to waste my time....

Btw you didnt answer my 2nd question (did you test it) , but you replied to my 1st question (did you read this somewhere) clearly affirmative ....IMHO it's worth mentioning that our definition of "research" apparently differs completely.....

 

[ondioline]

You may sit down and take a look here :

Uhh yeah dude, you may notice something consistent with those quotes: They're all on OpenCore, which uses its own APFS EFI loader. As in it's not written by Apple.

 

[KeesMacPro]

Uhh yeah dude, you may notice something consistent with those quotes: They're all on OpenCore, which uses its own APFS EFI loader. As in it's not written by Apple.

OMG please let me have patience.....

 

[MBAir2010]

there is only one way to find out!
what can go wrong?
if someone has the time and needs to run 32bit programs while enjoying the latest security  offers.
just one thing though
having Mojave and Catalina on the same drive might be worse on an unsupportive MacBook.
have fun!

updated Jan 16th, 2022:

back in Nov, 2021 this dual boot of mojave and catalina advice seemed daring and brash
now that i have a new mac mini which has a new ssd drive which western digital does not recognize the ssn#,
this dual boot is not a great idea and could effect the performance of both OS.

therefore, can someone use a external drive that is formatted as mac journal for catalina?
this drive has a time machined version of Mojave, Mac Journaled.
i do not think so.

 

[MBAir2010]

My advice is to NOT have both OS's on a single drive, partitioned or not.

If you want to run both, buy a cheap 2.5" SSD (128gb will do fine, some of these sell for $20), put it into a USB3 external enclosure, and install the OS onto that.

Now boot each OS (on each drive) completely "independent of" the other one.

Less trouble !

after many years or decade of great external OS boot advice i finally partitioned Catalina on an external drive.
1/3 is AFTS and the other mac journaled formatted on a spinning WD drive, usb3.
the process was slower, but once launched the OS is responsive with a much better picture!
but boring and I need to enter my password too many times, but HBO works perfectly unlike Mojave

now

what can't i partition the wd ssd internal drive on the mini like the external drive?
what trouble would i experience?

thanks in advance, i think you get the full credit here you deserve.
you hav save countless macs over these decade!

Edit: 2:52 PM
well, my internal ssd drive on the mac mini won't boot fast and the bluetooth and wifi wont work
seems to me I need a reboot and PRAM zap if that fixes the problem or item machine reinstall.

 

[DeltaMac]

Another opinion (along with actual use)
I have a 512GB SSD with all macOS systems from Leopard to Monterey. Leopard to Sierra are each on 32GB partitions (don't need a lot of space, it's only used to test full boots on Macs, and do some inter-system tests), so those take up 256GB of the drive. Boot systems from High Sierra to Monterey are each on shared volumes on one APFS container.
So, each boot system has access to whatever space is available on the 256GB container. There's currently a total of 12 volumes in that container, all with shared access to the 256GB of space.
Other than remembering that the older systems, on 32GB, don't have a lot of room to "play", the container allows individual systems to download a lot of files -- if I need to do that. I then get reminded that the OTHER systems in that container will run out of space, if I pull a lot of files down on the Big Sur system, for example.
That's probably not useful info for most users, but I get a lot of use from all those systems. I boot some kind of Mac from that drive almost every day, and I don't have to find an individual drive - boot systems are all on the same drive...
Yes, I always get the "Incompatible disk", but that's for Big Sur, and Monterey volumes when booting to an older system. Don't get an error from those volumes when booting something older than Sierra (they don't know anything about APFS, so that "mystery" container is completely ignored.
Bottom line, in my experience, you should have no problem at all with installing two different systems inside the same container. The APFS knows what to do with that configuration.

 

[gilby101]

Bottom line, in my experience, you should have no problem at all with installing two different systems inside the same container. The APFS knows what to do with that configuration.

Assuming that you give the boot volumes different names!

But, I think you are playing with fire:
1) Older implementations of APFS are not guaranteed to be compatible with newer ones - hence risk of messing up the APFS container;
2) What happens with the Recovery and Preboot volumes? Are they the same for each macOS version?
3) Just hope that all the snapshots don't get muddled (which really part of 1 above).

Whilst it might work on an older Mac, it wouldn't on an M1 Mac and perhaps not on a T2.

Much safer to put each macOS in its own APFS container/partition. But, if it works for you and you have a solid backup and recovery strategy, go for it.

 

[MBAir2010]

Bottom line, in my experience, you should have no problem at all with installing two different systems inside the same container. The APFS knows what to do with that configuration.

nice thourough explanation as always!

maybe you might know what i did wrong :
today i thought partitioning an external drive and running the macmini with catalina was a good idea.
that worked, then i unplugged the drive, restarted and things got bad
the bluetooth, wifi and usb drives were not functional on the mini,
thus crippling the ssd drive
after erasing the drive in a enclosed on the MacBook air, i just need to reinstall through time machine tomorrow.

 

[DeltaMac]

Assuming that you give the boot volumes different names!

But, I think you are playing with fire:
1) Older implementations of APFS are not guaranteed to be compatible with newer ones - hence risk of messing up the APFS container;
2) What happens with the Recovery and Preboot volumes? Are they the same for each macOS version?
3) Just hope that all the snapshots don't get muddled (which really part of 1 above).

Whilst it might work on an older Mac, it wouldn't on an M1 Mac and perhaps not on a T2.

Much safer to put each macOS in its own APFS container/partition. But, if it works for you and you have a solid backup and recovery strategy, go for it.

1) AFAIK - works OK. Each system was installed individually, so anything that would be installed with the basic system, was installed. There's 5 systems, with a total of 12 volumes, within the one container. Each system that should have its own recovery partition and Preboot volume, has that. There's nothing shared, except for being on the same drive. I have experimented with a variety of different boot tests, booting the system, then booting to Recovery to see if the Recovery system shows the related installer version. Seems to all work - but I have to remember to set the Startup Disk for each system that I boot to. That's probably the key to get the correct Recovery system to boot
This is really just an experiment to see if I could install that whole range on just one drive.
And - it really is quite useful for troubleshooting various Macs. (I wouldn't have that wide range on just one drive that I would want to use for real world work - I think there's too many possible things that could go wrong. but, it does work for what I need.

I have also discovered that the system that I use on that drive most often is Big Sur.
As long as I can turn off the boot security settings, there really isn't a problem on T1/T2 Macs.
However, M1 Macs don't seem to boot reliably to that "Master Booter" drive. Seems to take several attempts, with Monterey the only system that works from that drive to boot an M1 processor. Don't know why. I think I have to actually use an M1 Mac to install the boot system (I don't yet have my own AS Mac.)
Maybe I need to experiment with the Configurator 2 utility? Haven't tried that yet, either. Maybe in the next month or two.

 

[gilby101]

I think there's too many possible things that could go wrong. but, it does work for what I need.

I hope anyone that relies on your method does read that bit. And glad it works for what you need.

 

[Rimmsi]

Another opinion (along with actual use)
I have a 512GB SSD with all macOS systems from Leopard to Monterey. Leopard to Sierra are each on 32GB partitions (don't need a lot of space, it's only used to test full boots on Macs, and do some inter-system tests), so those take up 256GB of the drive. Boot systems from High Sierra to Monterey are each on shared volumes on one APFS container.
So, each boot system has access to whatever space is available on the 256GB container. There's currently a total of 12 volumes in that container, all with shared access to the 256GB of space.
Other than remembering that the older systems, on 32GB, don't have a lot of room to "play", the container allows individual systems to download a lot of files -- if I need to do that. I then get reminded that the OTHER systems in that container will run out of space, if I pull a lot of files down on the Big Sur system, for example.
That's probably not useful info for most users, but I get a lot of use from all those systems. I boot some kind of Mac from that drive almost every day, and I don't have to find an individual drive - boot systems are all on the same drive...
Yes, I always get the "Incompatible disk", but that's for Big Sur, and Monterey volumes when booting to an older system. Don't get an error from those volumes when booting something older than Sierra (they don't know anything about APFS, so that "mystery" container is completely ignored.
Bottom line, in my experience, you should have no problem at all with installing two different systems inside the same container. The APFS knows what to do with that configuration.

That's really impressive, but I have one question. If you need to remove one system, just wipe the container with a disk utility or are you forced to use another method?

 

[DeltaMac]

That's really impressive, but I have one question. If you need to remove one system, just wipe the container with a disk utility or are you forced to use another method?

Yeah, probably won't do that. There's just one container on that drive, with 5 systems from High Sierra to Monterey, all sharing the space in that one container. If I wanted to remove just one system completely, might be best to remove the container, and that would mean losing the other 4 systems, so I don't think I would worry much about removing all parts of the installed system. Older OS X systems are on individual partitions. Now that I think about it, my experiment with all those Mac OS systems, although it works, is just a novelty for most, not particularly useful, unless you have a lot of Macs, and you have some need to boot a wide range of Macs from mostly-identical systems

 

[haralds]

The reason why multiple versions can be installed in one Container is the concept of Volume Groups introduced in Catalina. Disk Utility from Catalina on will prompt you to delete other (hidden) members of the group. To delete an os, use the delete APFS volume function and follow the prompt. The other versions will not be harmed.
I personally would keep Mojave on a separate partition or disk.

 

[MBAir2010]

Mojave is still a vital operating system for those who still use 32Bit programs like CS4 daily.
And, with the sales of older intel Macs dwindling in price, perhaps purchasing an alternative Mac form the Mojave era
might be a great solution than partitioning drives.

I understand the risks of a bad battery or some other ailment an ebuyer might sell their MacBook or Mac mini
But there are several Mac affiliated websites that are offering these fine machines for $69-$200 THAT WORK!
they offer 1 year warrantees and will add extras them selves.

personally I used 3 MacBooks today while my 2010 MBAir ElCap is downloading 388 photos from iCloud.
and typing this on a MBP2012, Monterey and need to switch to Mojave later tonight via an extra drive.
dvd are so 2005!
:~)