Architect
Contain the blast radius
A B2B invoicing platform serves 4,000 companies from one shared stack. Last quarter a schema migration locked the shared database for half an hour and every customer went down at once. The new enterprise contracts cap what one incident may cost. Today a migration will lock the busiest database again at 10:00, for 30 minutes. Contain it, without spending more than today.
On the shared stack, 30 minutes of database lock cost about 2 % of the day's requests; contracts now allow 0.3 %. Every customer belongs to exactly one partition of the data, and no answer may be faked with a fallback. Today's stack costs about 16,000 dollars a month.
What your design must achieve
- Availability ≥ 99.7 %
- Requests answered with a fallback = 0
- Latency p99 < 250 ms
- Monthly bill < 14,000 $