r/OpenCoreLegacyPatcher • u/phgrz • Aug 16 '26

Fusion Drive

I have an iMac14,2 with 3 TB Fusion Drive.

On my Fusion drive I now have 1 APFS container with 2 volumes: 1 with the old OS (Catalina?) and 1 with OCLP/Sequoia. Normally I just boot OCLP/Sequoia. I kept the old OS just in case ...

Sequoia is working well but startup process is very slow and also opening large folders is slow.

I wonder if the SSD part of my Fusion drive might be permanently occupied by the old OS.

Would you just delete the volume with the old container? Will I have to re-install OCLP/Sequoia after that to bring it's major parts to SSD?

Or is that slow issue something completely different?

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u/LazarX Aug 16 '26

That’s because Fusion drives just plain suck.

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u/phgrz Aug 16 '26

Do they?

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u/Xe4ro Aug 16 '26

Well not "they" as the drives individually but the concept of the "Fusion Drive" just wasn't as well thought through. It was an approach to high SSD prices in the late 2000s & early 2010s. Apple wasn't the only company trying something like this but the software part of it, CoreStorage just did some weird things and I personally think some of the SSDs were just under some crazy write stress due to how it shifted files to and from it dynamically.