External SSD Partition/Reformat

[mitstoshi]

Just bought an external SSD ( 1 TB G-Drive Mobile performated HFS+) and like to have 2 or 3 partitions and reformat all to APFS. My questions are:
(1) Do I partition then reformat each partition or
(2) Reformat to APFS whole drive then do the partition?

Thanks for your advice!

 

[chabig]

You didn’t say why you think you need three partitions. So I will guess that what you really want is three separate volumes (icons on the desktop). There is a difference. Partitions are fixed size and don’t share space. Volumes can vary in size and share space. What you probably want is a single APFS partition with three APFS volumes in it.

 

[mitstoshi]

Sorry I want to create an external APFS volume served as a backup before I upgrade my late 2012 iMac with HDD from high Sierra to hfs+ Mojave. Two additional volumes can be used for time machine backup and/or other data backups. Terminology: drive/partitions (mine) vs partition/volume (yours) am I right? Or there is a difference under High Sierra and Mojave?

 

[DeltaMac]

I like APFS volumes! Erase the 1TB, formatting as APFS. You get one volume (actually a container). Add one or more volumes to that container (it's in the menus). Every volume in the APFS container shares the same space, so adding 2 volumes results in a total of 3 volumes, each sharing the 1TB space with the other two. Each volume then has access to the same free space. Try it!
(One problem with an external drive formatted APFS - older Macs won't see the drive at all, and Windows generally won't see the drive either, so sharing the drive with other computers can be challenging)

 

[chabig]

I think of the hierarchy as:

HFS+
Drive (hardware)
Partition (virtual) - Fixed size, doesn’t share space
Volume - just one volume per partition, same size

APFS
Drive (hardware)
Container (virtual) - Fixed size, doesn’t share space
Volume(s) - multiple volumes may exist in a container, all share space

 

[CoastalOR]

Sorry I want to create an external APFS volume served as a backup before I upgrade my late 2012 iMac with HDD from high Sierra to hfs+ Mojave. Two additional volumes can be used for time machine backup and/or other data backups. Terminology: drive/partitions (mine) vs partition/volume (yours) am I right? Or there is a difference under High Sierra and Mojave?

Time Machine only works with HFS+ (Mac OS Extended (Journaled)) so it will not work on APFS.

 

[mitstoshi]

Thanks everyone, I am confused now:

(1) So I got one external SSD (one container 1 TB with one volume 1 TB). If I add two volumes, I got one container 1TB with 3 volumes with unspecified sizes)? When adding volumes, does it need to specify a size for each volume? Can I add more volumes later?

(2) So under APFS, time machine is no longer available?

(3) When upgrading my late 2012 iMac with HDD (HFS+) on High Sierra to Mojave, I will get a HFS+ Mojave volume. If I clone using CCC, this volume to an external SSD APFS volume, I will get a APFS Mojave volume?

 

[CoastalOR]

Thanks everyone, I am confused now:

(2) So under APFS, time machine is no longer available?

(3) When upgrading my late 2012 iMac with HDD (HFS+) on High Sierra to Mojave, I will get a HFS+ Mojave volume. If I clone using CCC, this volume to an external SSD APFS volume, I will get a APFS Mojave volume?

(2) Time machine is available, but only on HFS+ format. You can only use Mac OS Extended (Journaled) for Time Machine.

Types of disks you can use with Time Machine on Mac

Use Time Machine on your Mac with a Time Capsule and with USB, FireWire, and Thunderbolt disks.

support.apple.com

(3) When you upgrade a HFS+ formatted High Sierra to Mojave (using the Apple Mojave installer app) it will automatically convert the format to APFS. CCC does not change the format of the Target drive (unless you are Cloning a Catalina Source drive - for a Catalina Source CCC will change the Target format to APFS automatically). CCC does not change the format of the Target drive for a Mojave Source. If the Target is formatted HFS+ (Mac OS Extended (Journaled)) and you clone a Mojave Source that is formatted APFS, the Target clone will remain Mac OS Extended (Journaled) format.

 

[DeltaMac]

1) If you specify a volume size, that's what you get. If you do not specify a volume size, then the volume used all the space of the container, unless another volume is assigned its own space (with a specified volume size). In that case, a new volume would share whatever space is provided in the container, which would be container size minus the spcified volume size. It's a choice, and you don't have to specify a size. (I don't fully understand how that works, but that's what happens as you add volumes to an APFS container). Keep in mind that APFS volumes in a container are not physical volumes, but are virtual volumes

 

[mitstoshi]

When you upgrade a HFS+ formatted High Sierra to Mojave (using the Apple Mojave installer app) it will automatically convert the format to APFS.

I thought that applies only to SSD or Apple Fusion drives but not to internal Mechnical HD like the one I have on my iMac. So it looks like I can upgrade to have a internal HFS+ Mojave volume? On the other hand, a HFS+ Mojave volume has a problem but not a APFS Mojave volume with Apple Security Updates. If it is true, I will need to have a APFS Mojave volume internal or external to do the updates. Any ideas?

I like APFS volumes! Erase the 1TB, formatting as APFS. You get one volume (actually a container). Add one or more volumes to that container (it's in the menus). Every volume in the APFS container shares the same space, so adding 2 volumes results in a total of 3 volumes, each sharing the 1TB space with the other two. Each volume then has access to the same free space

Is it possible to have a boot APFS volume on an external SSD and one internal boot HFS+ volume? That way, I can use CCC to do the updates between the two volumes when necessary?

 

[DeltaMac]

No - you misunderstand.
If you upgrade a spinning (mechanical) hard drive to Mojave (and newer), the installer automatically changes the boot volume format to APFS. Booting to a hard drive does not "protect" you from the APFS format.
With a hard drive upgraded thus, you can backup the drive to an HFS+ volume, using CCC, and the backup drive will be bootable, HFS format, and more usable in that condition. But, should you need to reinstall the system on that HFS format drive, the installer (again) will convert the volume to APFS. Just something you need to be aware of, if you need to stay with an HFS+ boot volume for some reason.

 

[mitstoshi]

No - you misunderstand.
If you upgrade a spinning (mechanical) hard drive to Mojave (and newer), the installer automatically changes the boot volume format to APFS. Booting to a hard drive does not "protect" you from the APFS format.
With a hard drive upgraded thus, you can backup the drive to an HFS+ volume, using CCC, and the backup drive will be bootable, HFS format, and more usable in that condition. But, should you need to reinstall the system on that HFS format drive, the installer (again) will convert the volume to APFS. Just something you need to be aware of, if you need to stay with an HFS+ boot volume for some reason.

Thanks! my iMac has 4 HFS+ partitions (MacintoshHD, 3 DataHD different sizes), when they are converted to APFS, would I get one container plus 3 volumes different sizes?

 

[DeltaMac]

No, AFAIK, the volume that you are updating to Mojave (the boot volume) would be changed to APFS. The other DataHD volumes would be left untouched.

 

[mitstoshi]

So my iMac would have one internal APFS MacintoshHD and 3 internal HFS+ DataHD? Two formats coexisted internally? Thanks!

 

[DeltaMac]

Yes.
For example, your internal boot drive might be Catalina, which gives you at least two active volumes in APFS format. The container itself is APFS.
If you decide to use Boot Camp to add a bootable Windows system to your internal drive, that process creates a new partition for Windows, which will absolutely not be APFS. So, yes, two (or more) formats for bootable systems can exist on the same device.

 

[mitstoshi]

I like APFS volumes! Erase the 1TB, formatting as APFS. You get one volume (actually a container). Add one or more volumes to that container (it's in the menus). Every volume in the APFS container shares the same space, so adding 2 volumes results in a total of 3 volumes, each sharing the 1TB space with the other two. Each volume then has access to the same free space. Try it!

Trying to erase the SSD using Disk Utility, do I erase the USB external physical disk (G-Drive mobile SSD Media) or the USB external physical volume (G-Drive mobile SSD R-Series)? Or they are same?

 

[DeltaMac]

Click on the "View" icon, choose Show All Devices.
Choose your G-drive device (not a volume). First G-drive item in the list is the device.
Click Erase. Name it whatever you like, then Mac OS Extended, journaled, then GUID Partition map
and finally, click the Erase button.
And that will completely erase your external SSD, leaving one partition.
Installing the macOS system (assuming 10.13 or later) will change the format to APFS. Some might erase with APFS format, but no real need to do that at that time.

 

[mitstoshi]

Thanks everyone. With CCC, I upgraded and have Mojave APFS and HFS+ formats on two volumes and HS HFS+ format on a third volumes.