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Comment by phren0logy | Hacker News Reader

Really? Faster than 2,519MB/s? I thought they were achieving this by ganging together 2 drives via their proprietary T2 chip.

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They admit in the article that a lot of this performance could be an illusion caused by the APFS instant cloning feature, which essentially just creates a new directory listing pointing to the existing file when you copy a file to the same volume. A separate copy of the data is only made when you make a change to one of the files.

It also appears that it doesn't copy the whole file upon changing one of the files. It only stores the changed portion. I assume this is block level. Pretty cool. But yes, SSD speed has very little to do with copy speed in this case.

I wonder if this could be used to infer information that users may not intend. For example, perhaps copying a file and fraudulently altering something in it at a specific time could be used as evidence in a trial.

The speed seems to be accurate for a high capacity PM981 or newer especially in raid Apple is just using bonker fast SSDs.

Isn’t this from the custom SSD controller they’ve been iterating over for years? [0] A variation of it even made its way into the iPhone [1]. Of course there are likely more hardware factors, such as binning.

0: http://www.iphonehacks.com/2015/04/apple-custom-ssd-controll...

1: https://bgr.com/2015/09/29/iphone-6s-macbook-ssd-storage-con...

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