Also, will converting the 400gb and 600gb partitions into "Free Space" partition work for this? How do I create Free Space partitions?

I'm using High Sierra 10.13.6 for this. In the end I want to add around 400 GB's of data to my main partition (BIGtb). I first tried converting all the partitions to APFS in hopes that I could do a simple merge, which failed. I then converted the two partitions back to OSX Journaled.

I will post pics that I believe may be informative.

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  • Your choice of words "intuitive", "allocate" and "relative" leave my confused in terms of what your question is. If you are asking for a simple procedure that would add the space allocated to volume 400+gb for current d... to volume BIGtb, then the answer is "there is not one". – David Anderson Jan 3 at 6:56
  • Is it possible to convert the 400+gb partition into "Free Space"? Then maybe I can increase my main APFS drive. – Don Lester Jan 4 at 2:21
  • APFS is a tricky bugger. Please see the answer to this recent post for some of the hairy details: apple.stackexchange.com/questions/345256/… – TJ Luoma Jan 4 at 3:14
  • @Don Lester: No. – David Anderson Jan 4 at 11:32

While the volumes stored in a APFS container are random access, the container itself is not. An APFS container is stored in a GPT partition. These types are partitions are sequentially stored on a drive. It is possible to expand a GPT partition to occupy space immediately before or after the partition. However, an APFS container can only be expanded to occur space immediately after, but not before. So you have two problems. First the ~400 GB of space is not immediately adjacent to the partition holding the APFS container. The partition with identifier disk0s3 is between this space and the partition holding the APFS container. Second, the space is above the APFS container. So even if you were to remove disk0s3, you still could not add the space to the APFS container.

To summarize:

  • While the drive and APFS allow random access, the GPT scheme does not.
  • APFS can be only be expanded downwards or shrunk upwards.

If you wish to wipe the entire drive and create 1.4 TB APFS container followed by JHFS+ partition, then enter the following command.

diskutil partitiondisk disk0 2 gpt apfs MyAPFS 1400G jhfs+ MyJHFS+ R

The EFI partition will be created automatically. If the above command was executed on a 2 TB drive, then result would be the partitioning shown below.

/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *2.0 TB     disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                 Apple_APFS Container disk1         1.4 TB     disk0s2
   3:                  Apple_HFS MyJHFS+                 599.7 GB   disk0s3

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +1.4 TB     disk1
                                 Physical Store disk0s2
   1:                APFS Volume MyAPFS                  24.6 KB    disk1s1

The command diskutil listfilesystems produces the output shown below. From this output, one can determine that the jhfs+ used in the above command means Mac OS Extended (Journaled).

Marlin:~ davidanderson$ diskutil listfilesystems
Formattable file systems

These file system personalities can be used for erasing and partitioning.
When specifying a personality as a parameter to a verb, case is not considered.
Certain common aliases (also case-insensitive) are listed below as well.

PERSONALITY                     USER VISIBLE NAME                               
APFS                            APFS                                            
  (or) APFSI
Case-sensitive APFS             APFS (Case-sensitive)                           
ExFAT                           ExFAT                                           
Free Space                      Free Space                                      
  (or) FREE
MS-DOS                          MS-DOS (FAT)                                    
MS-DOS FAT12                    MS-DOS (FAT12)                                  
MS-DOS FAT16                    MS-DOS (FAT16)                                  
MS-DOS FAT32                    MS-DOS (FAT32)                                  
  (or) FAT32
HFS+                            Mac OS Extended                                 
Case-sensitive HFS+             Mac OS Extended (Case-sensitive)                
  (or) HFSX
Case-sensitive Journaled HFS+   Mac OS Extended (Case-sensitive, Journaled)     
  (or) JHFSX
Journaled HFS+                  Mac OS Extended (Journaled)                     
  (or) JHFS+
Marlin:~ davidanderson$ 
  • I'm probably going to wipe this entire SSD drive and partition it into two pieces. Then I'll restore via Time Machine. How can I get my main drive towards the 'top' as you mentioned? (just in case I want to grow that partition in the future.) Thanks in advance. – Don Lester Jan 5 at 2:39
  • You need to be more specific. Can I assume you want a Apple_APFS partition followed by 600 GB Apple_HFS partition? Are you going to reinstall macOS, then recover your personal files from a Time Machine backup? – David Anderson Jan 5 at 3:29
  • Yes, I am now probably going to reinstall macOS then use Time Machine to back up. Your assumption is correct on the a 600 GB partition. I don't know what a HFS partition is. I'm don't think I can do that for a SSD drive. I'm probably going implement the 600GB partition as Mac Extended Journaled for time machine purposes. Your suggestion above seems sound though. I'll try it out probably, BUT how do I implement a Mac Extended Jornaled 600 GB partition instead of HFS? And will that command go through when I'm booted up on my main drive? Won't my computer shut down right away afterward? – Don Lester Jan 5 at 17:52
  • I update my answer. Basically, the command does create a Mac Extended Journaled 600 GB partition. Personalities (and aliases) are case independent, so jhfs+ is the same as JHFS+. – David Anderson Jan 5 at 23:08

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