How to optimize Fusion Drive structure on iMac for faster boot time?

2017 27inch iMac. Boot up seems to take long so I ran disk utility and got the attached information. Does this look optimal?



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iMac 27″ 5K, macOS 13.7

Posted on Mar 24, 2025 8:30 PM

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Posted on Mar 25, 2025 6:43 AM

As @den.thed already posted, your screenshots look normal for a Fusion drive.


Fusion drives consist of a small SSD coupled with a larger HDD (hard disk drive). What I think you are experiencing is the reality that APFS is not "kind" on HDDs. APFS was designed for SSDs; when used on an HDD, the way APFS works has the effect of slowing down HDD performance, and it gets especially noticeable once the HDD is about 50% full, which is about where your disk is at this point.


If you want to keep this 2017 iMac and improve performance, I also vote for using an external SSD as your boot drive. If you choose to go this route, get an external drive that supports USB 3.1 Generation 2 (up to 10 Gbps) and connect it to one of the USB-C ports on your iMac. You can still use the internal Fusion drive for storage.

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How to optimize Fusion Drive structure on iMac for faster boot time?

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