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Izzy930 Author

Level 1

4 points

Help please community need your input on this task

Erasing “SSD SSD Media” (disk2) and creating “Izzy Backup”

Unmounting disk

Creating the partition map

Unable to write to the last block of the device. : (-69760)

Operation failed…

the ssd external only reads and writes on my windows 10 and 11 machines but does not mount or initialize on my macbook pro retina 15 inch mid 2015 got machine in late 2016 bestbuy limited edition that apple store didnt even have now with mac os 12.7.6 no further capabilities to update os versions need help formatting new 8tb ssd usb drive for read and write for cross platforms from older windows mac linux and unix and android or chromebooks to latest versions of all platforms

MacBook Pro 15″, macOS 12.7

Posted on Oct 11, 2026 3:05 PM

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Answer 1

Oct 11, 2026 3:30 PM in response to Izzy930

The Mac insists that when initializing a new device, it MUST be able to write the last block on the device, else

the device has failed or the device is not what it says.

If you paid an appropriate amount, it appears to be defective and you should return it.

was that device sold at bargain price with no maker-name? It may not be what it says.

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Answer 2

MrHoffman

Level 10

166,589 points

Oct 11, 2026 4:09 PM in response to Izzy930

If you paid substantially less than about $1,200 for that 8 TB SSD new, it’s quite possible you got scammed.

Some fraudulent flash detection tools: https://github.com/AltraMayor/f3

Otherwise, I'd wonder if the SSD is merely defective.

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