Every migration is a system that hit a threshold.

Every entry here is a real company whose system climbed past a limit, and what they did about it. The originals are deep engineering write-ups; this site retells each one as the incident it actually was — a calm baseline, a number that started climbing, the moment it broke, and what they shipped to fix it.

Two questions get answered every time: why did this happen, andwhy was this the fix. The facts, numbers, and decisions belong to the original authors and are never altered. Every page links back to its source.

Know a migration we should cover? Suggest it by email — company, what it moved from and to, and a source we can cite.