RAID Creation Failed. HELP!

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kimfromreno Author

Level 1

6 points

RAID Creation Failed. HELP!

I bought two new 2TB external SSD drives to set up as RAID 1 (mirrored). They boot immediately and open in Finder.

1) I erased and reformatted each drive to "Mac OS Extended (Journaled)" for "RAID 2TB 1" and "RAID 2TB 2"

2) Within "RAID Assistant", I selected "Mirrored (RAID 1)".

3) Within "Disk Selection", I checked the boxes for the two reformatted drives and selected "RAID Slice" for each disk.

4) I named the expected RAID "2TB RAID 1", selected "Mac OS Extended (Journaled)", left the Chunk size at "32K", left the box checked for "Automatically Rebuild", and hit "Next".

5) "Process Complete" page displayed immediately saying, "RAID Creation Failed - This operation is not supported on this partitioning scheme. : (-69801)

What's the deal? Any suggestions? 2019 MacBook Pro 16" running macOS Sonoma.

MacBook Pro 16″, macOS 14.7

Posted on Jul 14, 2025 7:50 PM

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Answer 1

Top-ranking reply

Jack-19

Level 8

46,182 points

Jul 15, 2025 10:50 AM in response to kimfromreno

I have looked everywhere and cannot find or have not seen a "scheme" popup window or any reference to "GUID".

When you erase and reformat the drives, be sure to choose View > Show All Devices in Disk Utility, then select the external SSD entry at the top of the hierarchy and click erase. You should then see the option for scheme.

-Jack

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Answer 2

Jack-19

Level 8

46,182 points

Jul 14, 2025 11:46 PM in response to kimfromreno

Hey there!

Check that the external SSDs are formatted using the GUID Partition Scheme, then try to create the RAID in Disk Utility again.

If Disk Utility still can't create the RAID, you could use backup and cloning software, such as Carbon Copy Cloner, to configure a clone of one external SSD to another, simulating a RAID 1 type setup. Or, you could look into an SSD hardware RAID product, such as the 4.0TB OWC Mercury Elite Pro Dual mini, which you can configure into RAID 1 mode and have 2TB of usable storage space.

Hope this helps!

-Jack

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Answer 3

Jack-19

Level 8

46,182 points

Jul 15, 2025 11:45 AM in response to kimfromreno

Choose the "PNY PNY RP60 PSSD Media" entry for both. Scheme will appear.

-Jack

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Answer 4

kimfromreno Author

Level 1

6 points

Jul 15, 2025 7:01 AM in response to Jack-19

I erased and formatted the drives as "Mac OS Extended (Journaled)" when they first arrived.

I have looked everywhere and cannot find or have not seen a "scheme" popup window or any reference to "GUID".

I notice that I "Partition" is greyed-out.

I have set up and owned many RAIDs and have never had this problem.

None of the Community pages I have seen address anything like this.

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Answer 5

kimfromreno Author

Level 1

6 points

Jul 15, 2025 11:27 AM in response to Jack-19

I guess I posted the wrong screenshot. I did select "Show all devices" and reformatted the disks individually, naming them "RAID 2TB 1" and "RAID 2TB 2".

The only choices I was given for either were these:

Those are it. No option for "Scheme" to be found.

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Answer 6

kimfromreno Author

Level 1

6 points

Jul 15, 2025 12:52 PM in response to Jack-19

Beautiful! It worked perfectly! RAID up and running. Thank you, Jack!

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