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420 points speckx | 2 comments | | HN request time: 0.44s | source
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GeekyBear ◴[] No.44533662[source]
The article speculates on why Apple integrates the SSD controller onto the SOC for their A and M series chips, but misses one big reason, data integrity.

About a decade and a half ago, Apple paid half a billion dollars to acquire the patents of a company making enterprise SSD controllers.

> Anobit appears to be applying a lot of signal processing techniques in addition to ECC to address the issue of NAND reliability and data retention. In its patents there are mentions of periodically refreshing cells whose voltages may have drifted, exploiting some of the behaviors of adjacent cells and generally trying to deal with the things that happen to NAND once it's been worn considerably.

Through all of these efforts, Anobit is promising significant improvements in NAND longevity and reliability.

https://www.anandtech.com/show/5258/apple-acquires-anobit-br...

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wpm ◴[] No.44533751[source]
Note that this isn't too long after Apple abandoned efforts to bring ZFS into Mac OS X as a potential default filesystem. Patents were probably a good reason, given the Oracle buyout of Sun, but also a bit of "skating to where the puck will be" and realizing that the spinning rust ZFS was built for probably wasn't going to be in their computers for much longer.
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1. GeekyBear ◴[] No.44533875[source]
When Apple announced the creation of APFS they mentioned that their intent was to handle data integrity at the hardware level.
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2. throw0101c ◴[] No.44534173[source]
See:

> Apple File System uses checksums to ensure data integrity for metadata but not for the actual user data, relying instead on error-correcting code (ECC) mechanisms in the storage hardware.[18]

* https://en.wikipedia.org/wiki/Apple_File_System#Data_integri...