Comment by hinkley

There’s a really old trick with HDDs where you buy a big disc and then allocate less than half of it. There’s more throughput on the first half of the disk, more tracks per cylinder so fewer seeks, and never having to read half the disk reduces the worst case seek time. All increase IOPs.

But then what do you do with the other half of the disk? If you access it when the machine isn’t dormant you lose most of these benefits.

For deep storage you have two problems. Time to access the files, and resources to locate the files. In a distributed file store there’s the potential for chatty access or large memory footprints for directory structures. You might need an elaborate system to locate file 54325 if you’re doing some consistent hashing thing, but the customer has no clue what 54325 is. They want the birthday party video. So they still need a directory structure even if you can avoid it.