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How To Reformat The Fusion Drive When It Isn't The Startup Disk?

My 27-inch iMac from 2017 has a Fusion Drive installed. The performance didn't impress me, so I went with an external SSD Thunderbolt drive instead. I purchased an Envoy Express from OWC and installed a 1 TB 2280 M.2 NVMe SSD inside of it. With Photoshop launching in less than 4 seconds, the performance boost is astounding. Because of this, I was still able to replace the Fusion drive with an SSD and get the most of its performance benefits without having to disassemble my iMac. I'd like to reformat the Fusion Drive just for storage, but Disk Utility won't let me.. It prevents me from reformatting and constantly telling me that files are in use. Since the Envoy Express is my startup drive and has a complete copy of Big Sur installed, I'm not clear what is running on the Fusion Drive. Does

Best Answered by

iBoysoft author Vain Rowe

Vain Rowe

Answered on Monday, February 19, 2024

Hi there, since the Fusion Drive is installed with macOS when it comes to you, you can formatting it by selecting each volume in Disk Utility. If this method fails and pops up an error, you can boot your iMac into the Internet Recovery Mode to complete the reformat task from the Fusion Drive instead of the external startup disk.

You can read this article to know how to boot into Internet Recovery Mode: Internet Recovery Mode on Intel and M1 Mac Explained

And if you want to fix the split Fusion Drive, please visit this post: How to Fix A Split Fusion Drive on iMac And Recover Data?


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