Using partitions to preserve 32-bit games while upgrading to Catalina?

[Achiever]

I am still on Mojave on three different Macs, largely as I don't want to say goodbye to a few legacy games which are 32-bit only and will not be updated. This has kept me from upgrading to Catalina, but I may need to do so for some peripherals and I realistically can't stay on Mojave forever. I little sleuthing has suggested that I might be able to create a bootable Mojave partition on my Macs, which will allows me to upgrade to Catalina on the main partitions, but allow me to preserve my 32-bit lifestyle in that minor partition. Is that the case? Have folks tried that and found it to be successful? I welcome input, experiences, better options, etc.

FWIW, the Macs are a SSD 2015 MBP, and 2 iMacs, one with SSD only and one a fusion drive. Not sure if any of that makes a difference, but just in case...Thanks in advance!

 

[chabig]

Catalina still runs 32 bit apps. Big Sur won't.

 

[Achiever]

Catalina still runs 32 bit apps. Big Sur won't.

I'm not sure I agree with you a hundred percent on your police work, there, Lou.

 

[Ritsuka]

I would put Mojave on an external SSD, s you can move it around your Macs and it won't use space on the internal disk.

 

[chabig]

You're right. My memory is failing me. Catalina killed 32 bit. Given that, I don't see you couldn't make a bootable Mojave partition, but it would probably be cleaner to just put Mojave on an external SSD along with the games you like. You can also run Mojave inside a virtual machine, such as Parallels.

 

[Fishrrman]

OP:
I would NOT recommend having Catalina and Mojave on the same drive, even using different partitions.

If you want to keep backward compatibility for your 32 bit apps, have Catalina and Mojave installed on different DRIVES. I sense this will be a more reliable long-term solution.

 

[joevt]

Put as many partitions as you want on the same drive or multiple drives. macOS has no problem with that. Just don't add extra volumes to APFS partitions.

diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *240.1 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:       Microsoft Basic Data Windows 8.1 on Electra  109.2 GB   disk0s2
   3:       Microsoft Basic Data Windows 10              130.7 GB   disk0s3

/dev/disk1 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *960.2 GB   disk1
   1:                        EFI EFI                     209.7 MB   disk1s1
   2:                  Apple_HFS ElCapitan               64.4 GB    disk1s2
   3:                 Apple_APFS Container disk5         64.6 GB    disk1s3 # Mojave4
   4:                 Apple_APFS Container disk3         86.8 GB    disk1s4 # Mojave5
   5:                  Apple_HFS Yosemite                64.4 GB    disk1s5
   6:                 Linux Swap                         42.8 GB    disk1s6
   7:           Linux Filesystem                         21.5 GB    disk1s7 # Ubuntu 20.04 LTS
   8:                  Apple_HFS Shell                   524.3 MB   disk1s8
   9:                  Apple_HFS rEFIt                   524.3 MB   disk1s9
  10:                  Apple_HFS rEFInd                  524.3 MB   disk1s10
  11:                  Apple_HFS Mojave4 Boot            21.0 MB    disk1s11
  12:                  Apple_HFS Mojave5 Boot            21.0 MB    disk1s12
  13:                  Apple_HFS Games                   214.7 GB   disk1s13
  14:                  Apple_HFS Storage                 353.7 GB   disk1s14
  15:           Linux Filesystem                         25.0 GB    disk1s15

/dev/disk2 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *960.2 GB   disk2
   1:                        EFI EFI                     209.7 MB   disk2s1
   2:                  Apple_HFS Sierra                  90.0 GB    disk2s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk2s3
   4:                  Apple_HFS HighSierra              90.0 GB    disk2s4
   5:                 Apple_Boot Recovery HD             650.0 MB   disk2s5
   6:                  Apple_HFS Mojave3                 99.0 GB    disk2s6
   7:                 Apple_Boot Recovery HD             650.0 MB   disk2s7
   8:                  Apple_HFS Untitled 115GB          115.6 GB   disk2s8
   9:                 Apple_APFS Container disk4         249.5 GB   disk2s9 # Catalina
  10:                 Apple_APFS Container disk6         200.0 GB   disk2s10 # Mojave6
  11:                  Apple_HFS Mojave6 Boot            52.4 MB    disk2s11
  12:                  Apple_HFS Catalina Boot           52.5 MB    disk2s12

/dev/disk7 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *5.0 TB     disk7
   1:                        EFI EFI                     209.7 MB   disk7s1
   2:       Microsoft Basic Data Windows 7 32 b          42.9 GB    disk7s2
   3:       Microsoft Basic Data Windows 7 64 b          75.2 GB    disk7s3
   4:                  Apple_HFS Lion3                   106.9 GB   disk7s4
   5:                 Apple_Boot Recovery HD             650.0 MB   disk7s5
   6:                  Apple_HFS Multimedia              322.1 GB   disk7s6
   7:                  Apple_HFS Big                     279.2 GB   disk7s7
   8:                  Apple_HFS Lion2                   42.8 GB    disk7s8
   9:                  Apple_HFS Classic                 42.9 GB    disk7s9
  10:                  Apple_HFS Mavericks               90.9 GB    disk7s10
  11:                 Apple_Boot Recovery HD             650.0 MB   disk7s11
  12:                  Apple_HFS MountainLion            69.8 GB    disk7s12
  13:                 Apple_Boot Recovery HD             650.0 MB   disk7s13
  14:                  Apple_HFS Void1                   3.7 TB     disk7s14
  15:                  Apple_HFS Lion                    32.3 GB    disk7s15
  16:                 Apple_Boot Recovery HD             752.0 MB   disk7s16
  17:                  Apple_HFS SnowLeopard             37.6 GB    disk7s17
  18:                  Apple_HFS Leopard                 42.9 GB    disk7s18
  19:       Microsoft Basic Data FREEDOS                 1.1 GB     disk7s19

 

[Taz Mangus]

Put as many partitions as you want on the same drive or multiple drives. macOS has no problem with that. Just don't add extra volumes to APFS partitions.

You can have Mojave on a separate Volume in the same Container as Catalina. It's Big Sur that needs a different Container than Catalina and Mojave.

 

[joevt]

You can have Mojave on a separate Volume in the same Container as Catalina. It's Big Sur that needs a different Container than Catalina and Mojave.

If Catalina and Mojave are in the same folder, do they share a Recovery? I think Preboot gets a new folder for each root system (the folder name is the UUID of the root volume that it belongs to). They can probably both use the same VM volume.

Can you put two Catalinas in the same APFS container? Maybe not because of the Data partitions? I haven't tried putting two OSs in the same container before. It's a more efficient use of space since all the space of a container is shared among all the volumes in the container.