How can I have APFS and Mac OS Extended (Journaled) on the same SSD?

I solved the problem somewhat accidentally. It suddenly occurred to me that I might need to create a partition on the SSD by using Disk Utility WITHIN the recovery mode. BINGO!

The scary part was in watching the detailed process when it came to “Shrinking APFS data structures.” I lost track of time, but I’d say that it took more than fifteen minutes which is a long time when you come to fear that the computer may be locked up due to the following message:

warning: Overallocation Detected on Main device.

See the picture below. I apologize for the quality of the photo, but I had to use my camera since I couldn’t take a screenshot.

I am guessing that the shrinking action was due to the overallocation. The following picture shows the Mavericks Partition:

I might add that I have since renamed the SSD partition High Sierra since both partitions with their respective operating systems are on the internal SSD.

Prior to this I had Mavericks on a thumb drive which proved to be much slower and limited in capacity. Bottom line: maintaining a partition with the Mavericks OS is much cheaper than updating FileMaker and Finale. I hope that this explanation will help others wanting to maintain two different operating systems with different file formats.

FINALLY: When launching Mavericks The App Store will offer to update Mavericks to High Sierra. DO NOT DO THIS! Otherwise, all your work will be for nothing.

BDAqua,

Thank you for your prompt reply. Are you saying that I should maintain my one container and simply add a volume to it, formatting the new volume in Mac OS Extended (Journaled)?

Before I hit the "Partition" button, do I click on "TOSHIBA-TR150 M..." or "Container disk1" or "SSD"? Thanks

I'm not sure either. However, I'm under the impression that I need to click on the correct one of three items before partitioning. I'm going to call it a day for now. I'll continue with this task tomorrow. Again, thanks for your help.

Lexiepex,

Thank you for your response. Yes, I suspect that I will have to erase and start over; however, I was under the impression that I could partition and add volumes to a container. At this point, it appears that I cannot partition the disk, nor the container, nor add a volume. As the second screenshot shows, it indicates the SSD as 480 GB in size. I am unable to partition it in any way. Then, if I attempt to add a volume, it only allows me to add In APFS format.

It would be most helpful if somebody could simply state the steps in:

1.

2.

3.

rather than try to explain it in one sentence.