How to estimate disk space.

A few years ago while interviewing Nelson Elhage for Staff Engineer,he mentioned “estimation” as a particularly valuable skill. I hadn’t thought much about the ideaof estimation as a skill, but his comment made me remember one of the best architecture interviews I’ve ever given,where the candidate was able to significantly narrow down the possible solutions by asking for a few details(as best I can remember: queries per second, expected number of rows, and necessary columns).

Historically, I...