Imac 2017 Fusion drive to fast

Question

Imac 2017 Fusion drive to fast

Hello, this may seem a little strange to ask and maybe I'm missing some picture of the puzzle.

I have a 27" 2017 Imac 4.2Ghz i7 with 64gb ram Radeon Pro 580 8GB graphics.

My write speeds are 750MB/s and Read is 2309 MB/s , I'm sure that when I first purchased this new the writes were nowhere near that, I've never had the front off and the only thing I have done is upgrade the ram and plugged in outside drives which are spinning drives and 1 ssd which I tested and it read 430 roughly on reads& Writes.

Does any chap no what is happening here.

I have added 2 photos with the second one which I find interesting as it looks like there's 2 Macintosh HD's.

Thanks for any advice.

iMac 27″ 5K, macOS 11.1

Posted on Sep 8, 2021 8:22 PM

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Answer 1

Jack-19

Level 8

46,020 points

Sep 8, 2021 8:29 PM in response to muzicfromcapalaba

Welcome to the Apple Support Communities.

Are you saying you think your Fusion Drive is too fast? The speeds you are getting on your Fusion Drive are average. Nothing is wrong.

The reason your external SSD is slower than your Fusion Drive is because the smaller SSD that makes up the Fusion Drive is extremely fast (~2000 MB/s) instead of your most likely SATA external SSD (~430 MB/s over USB).

Jack

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Answer 2

Sep 8, 2021 9:45 PM in response to Jack-19

Hello Jack, thank you for responding, what I mean by too fast is my write speeds use to be around low 400 and they are showing 750 and I can't see why they are showing this with a fusion drive.

Read speeds were always fast having the blade/little ssd.

Do you know the fusion drive speeds from new in one of these 2017 which may clarify things for me .

Regards Dave.

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Answer 3

Jack-19

Level 8

46,020 points

Sep 8, 2021 9:47 PM in response to muzicfromcapalaba

Fusion Drive write and read speed tests are always different, because it tests the speed of the SSD and the HDD and combines it into a single value.

Your speeds right now are fine. Earlier tests could be different for a number of reasons.

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Answer 4

Sep 8, 2021 9:50 PM in response to Jack-19

Thanks Jack, I did not know it combines it to give a single value. Thank again for your help :)

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Answer 5

Jack-19

Level 8

46,020 points

Sep 8, 2021 9:52 PM in response to muzicfromcapalaba

By "combine" I meant "average", but yes it is just a single value from two drives.

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Imac 2017 Fusion drive to fast

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