Hello! I have a MacPro 5,1 running macOS 10.14.6. I'm trying to partition a 5TB external HDD into 3 partitions - the first one 2TB, the second 1TB, and the third 2TB. The first step, I erased the disk using Disk Utility with Mac OS Extended (Journaled) and GUID as my settings. I then selected the Disk (not the Volume) and went into 'Partition', and used the '+' button to create the three partitions. I then used the 'resize' buttons on the disk wheel to create the three partitions (2,1,2). I then hit 'Apply' and 'Partition' and waited for it to do it's thing, but it failed to complete the task without giving any error message as to why it couldn't. I tried a few different times using APFS to format the disk, or slightly changing the size of the partitions, but each time it would fail. I'm following online instructions and Youtube videos where it seems to work no problem, so I really don't know what I'm doing wrong? Any insight would be greatly appreciated, thanks!
PS. In one video it said it was important to use the 'resizer' on the disk wheel and not entering the partition size directly in the box as this would lead to partition disk size errors. In their example, even though they wanted a 1TB size partition, the disk wheel would resize it to something slightly less. But when I did it, it would make three perfect partitions of 2, 1, and 2. I'm guessing this might be the problem, since it's not making each one slightly less, but I really don't know....like I said, I tried to manually make the partitions slightly smaller, but this failed as well...
PS. In one video it said it was important to use the 'resizer' on the disk wheel and not entering the partition size directly in the box as this would lead to partition disk size errors. In their example, even though they wanted a 1TB size partition, the disk wheel would resize it to something slightly less. But when I did it, it would make three perfect partitions of 2, 1, and 2. I'm guessing this might be the problem, since it's not making each one slightly less, but I really don't know....like I said, I tried to manually make the partitions slightly smaller, but this failed as well...