Re: SSD TBW

On Fri, 21 Aug 2026 12:56:40 -0700, Don Y wrote:

> The firmware in spinning rust controllers has matured over decades.
> This is not the case with SSDs (especially early entrants to the
> market).

First of all, rust isn’t magnetic.

Secondly, flash-storage firmware is indeed very complex -- most of
that complexity seems to go into making the device behave like a
magnetic disk drive. Details are proprietary, but certain filesystem
experts have voiced the opinion that the firmware implements something
resembling a log-structured filesystem.

(You know how filesystems nowadays commonly have journals? The journal
is usually treated as a temporary holding place, to store transactions
in progress, to allow clean recovery from crashes. But once you have a
journal, you can consider the regular part of the filesystem to be
redundant; what if the filesystem itself was all journal? That’s a
“log-structured filesystem”.)

You could do away with most of this complexity just by using an
OS-level filesystem that has wear-levelling built into its allocation
algorithms. Several of these exist for the Linux kernel, and I think
are deployed in embedded applications. Unfortunately I don’t think you
can get regular consumer products designed for such usage, since the
lowest common denominator, namely Microsoft Windows, has no capability
to take advantage of them.