Formatting and external SSD for macOS

Hi All,

Looking for help from any one versed in MacOS.

I’m formatting my new SSD for music storage and flowed instructions using the Disk Utility. When I click on the disk unit I get this in return, with blue and red bars, is this correct? The drive is a 2TB, both the blue and red bars indicate 2TB. I’m used to HDD and it usually just shows one bar for the amount of space that is used up.

Then if I want to further divid the container I get the pie chart with it divided in two, with 2TB on either side. Is this correct?

Thanks in advance for your help.

It looks as though you (presumably, or someone else?) have partitioned your hard drive.

My suggestion would be to research macOS drive partitioning a little further so that you can arrive at the exact setup you really want. These may help:

Note that any data on a drive which you subsequently partition is lost. There are apps which claim to be able to recover such data if you change the disk’s partition scheme; but they may not be as reliable as you hope.

In short, what you’re seeing in Disk Utility seems to be as expected. But is it what you want? If you bought a 4TB drive and want it to appear as two ‘virtually separate’ 2 TB volumes, then you’re all set. But it probably pays to confirm that. Good luck!

Thanks Mark,
This is what I can’t figure out. I don’t have a 4TB SSD, it is only 2TB.

How can it be partitioned with 2TB on both partitions?!

I followed the instructions for format the “top of the hierarchy” after I selected the storage device. And erase.

This is the first time I’m seeing the red and blue bars, don’t know what it means.


I suspect that in your first screen shot the two bars correspond to the Container and Volume - because they are (were?) both 2 TB. The colours here do not indicate anything other than two colors… red and blue.

And in your second - perhaps (since I assume you hadn’t yet actually partitioned the device) a display with the two 2TB partitions as starting points.

This guide might help.

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What happens if you hit this?


Thanks for all the help. The Guide from OWC is very helpful.

Came back to it this morning and even though I did absolutely nothing, it looks like it fixed itself. Both the device and container, bars and pie chart look like I expected when first reformatted. I’ll add this to the big book of mysteries.

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Very welcome, Jason!

Isn’t it just!

May I countersign that book, please :slight_smile: !

Though I suspect that if you had ‘experimented’ with it a little like this, that might have nudged it in the right direction.

Glad it’s behaving as it should.

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