Recommended APFS Plan for multiple macOS versions on a NVME SSD

[GoGrater]

Hello, I am trying to figure out the best way to set up my new 1TB NVME SSD. This will be my boot drive with multiple OS versions. There should be plenty of space.

APFS and SSDs are new to me and there's probably some dos and don'ts I'm unaware of. So far, I've formatted the SSD to APFS. By default, I have one volume in a container. I understand that a container may contain multiple volumes. Also, that I don't need to allocate a fixed amount of space per volume since it can grow to available space in the container.

Should I start with the one volume and when I am ready to install another OS then add another volume to the same/existing container ? Or is there a better way to arrange the volumes and containers for my use case, such as multiple containers?

 

[Taz Mangus]

Think of a container as a partition in APFS. When you create a new partition you are creating a new container and a single default volume within the container in APFS. If you are planning on having MacOS versions, put each in its own partition. Depending on which version of the MacOS you are planning on using you may need to format a partition as HFS+. A new HFS+ partition would not create a container.

 

[GoGrater]

Think of a container as a partition in APFS. When you create a new partition you are creating a new container and a single default volume within the container in APFS. If you are planning on having MacOS versions, put each in its own partition. Depending on which version of the MacOS you are planning on using you may need to format a partition as HFS+. A new HFS+ partition would not create a container.

Thanks, Taz. So if I understand correctly, put one macOS per volume per container. For a second macOS, create another container and put the OS in the single volume in that container. For my knowledge, what is the benefit to arrange in this fashion instead of two volumes in the same container? e.g. Is it more efficient since each OS is in contiguous space?

Good thinking on the version of macOS. I will probably have High Sierra, Mojave and eventually Catalina. However, I might have Yosemite for one application and that would requires HFS+.

 

[Taz Mangus]

Thanks, Taz. So if I understand correctly, put one macOS per volume per container. For a second macOS, create another container and put the OS in the single volume in that container. For my knowledge, what is the benefit to arrange in this fashion instead of two volumes in the same container? e.g. Is it more efficient since each OS is in contiguous space?

Good thinking on the version of macOS. I will probably have High Sierra, Mojave and eventually Catalina. However, I might have Yosemite for one application and that would requires HFS+.

You could create one APFS partition and have separate volumes for each OS as along as the OS supports APFS. But keep in mind that all Volumes within a Container are limited to fit within the size of the Container.

Although, it occurs to me what if you are running a HFS+ restricted macOS such as Yosemite and you want to boot to one of the macOS that support APFS. Would you be able to use the boot start options (press option-key at restart) and it would recognize the APFS partitions. Not sure if the boot start option is tied to a particular macOS filesystem format.

 

[GoGrater]

You could create one APFS partition and have separate volumes for each OS as along as the OS supports APFS. But keep in mind that all Volumes within a Container are limited to fit within the size of the Container.

Although, it occurs to me what if you are running a HFS+ restricted macOS such as Yosemite and you want to boot to one of the macOS that support APFS. Would you be able to use the boot start options (press ion option-key at restart) and it would recognize the APFS partitions. Not sure if the boot start option is tied to a particular macOS in how it understands the partition table format.

For High Sierra and later, I could either put multiple volumes in a large container -or- put one volume per container. Sounds like either option is OK, and there shouldn't be a problem of running out of space with either option as long as I allocate sufficient space for all volumes in a container.

OTOH, you bring up a good point about how will I be able to switch from Yosemite (HFS+) to Mojave (APFS). I have a non-EFI GPU which means I can't select a startup volume during bootup. I have to use System Preferences to select the startup volume, but if Yosemite doesn't recognize APFS, then how can I pick a macOS in an APFS volume when I'm booted to Yosemite???

Maybe someone with this setup can chime in.