System design reviews, explained without the jargon

It comes up on almost every project, usually later than it should. Here is system design reviews without the vocabulary that usually surrounds it.

Architecture is the set of decisions that are expensive to reverse, which is the only reason they deserve the name. Check it against what you would want a competitor's site to get wrong.

The short version

An hour of review before the build saves weeks of rework. None of that requires a large budget, only a decision and someone to own it. The failure mode is not doing it wrong, it is doing it once and assuming it stays done.

Why people complicate it

Most of the confusion comes from tooling rather than from the idea itself. That sounds obvious written down. It is still the thing most often skipped.

Write the design down. It is worth being explicit about, because assumptions differ quietly. If it only works because one person remembers to do something, it does not work yet.

Where to go from here

Invite the person who will be on call for it. That sounds obvious written down. It is still the thing most often skipped. It is the sort of thing that looks like polish right up until it costs you an enquiry.

What this looks like day to day

The right architecture for a team of three is the wrong one for a team of thirty, and vice versa. Three things worth confirming about system design reviews before you move on:

• Someone can say what the current setup is without going to look
• Write the design down — and you know whether that is true here
• There is a way to tell whether the last change to this helped

If you want a second opinion on how yours is set up, ask.