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From: Lawrence D'Oliveiro <ldo@nz.invalid>
Newsgroups: comp.arch
Subject: Re: Is Parallel Programming Hard, And, If So, What Can You Do About
 It?
Date: Mon, 12 May 2025 22:35:57 -0000 (UTC)
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On Mon, 12 May 2025 08:05:56 +0200, Terje Mathisen wrote:

> Lawrence D'Oliveiro wrote:
>>
>> One of my pet peeves is disk drives with memory caches in them. Why?
>> 
> For reads it allows the disk to always read full sets of sectors, the
> following blocks are likely to be needed soon anyway.

Leave that up to the OS I/O optimization algorithms. Because they know 
things about the data that the drive doesn’t.

> For writes, as long as the drive has enough energy (maybe in the form of
> spinning inertia, or a hefty cap?) the always be able to save the buffer
> cache to spinning rust, it can allow operations to complete immediately,
> or as soon as the data has been transferred into the disk cache.

In other words, telling lies to the OS that the write has completed when 
it hasn’t. This kind of thing can really stuff up filesystem integrity 
guarantees.