Why system design reviews matters more than it looks

The advice here is unglamorous, which is probably why it gets skipped. System design reviews is easy to treat as a detail, and that is exactly why it is worth a few minutes of attention.

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.

What is actually at stake

An hour of review before the build saves weeks of rework. In practice this is a scheduling problem more than a technical one. It is worth deciding this deliberately rather than inheriting whatever the last person set up.

Write the design down. It is worth being explicit about, because assumptions differ quietly. It rarely shows up as a line item, which is exactly why it slips.

What to watch for

Invite the person who will be on call for it. This is the sort of thing that compounds, quietly, in both directions. The teams that stay on top of it are the ones who put it on a calendar rather than a wish list.

In practice

Most systems fail at the seams rather than inside any one component. Three things worth confirming about system design reviews before you move on:

• Someone can say what the current setup is without going to look
• a whiteboard photo is not a record — and you know whether that is true here
• There is a way to tell whether the last change to this helped

None of this needs a rewrite. Most of it is a morning's work once someone decides to do it.