Mediumsystem-designcdnstatic

CDN and object storage

Acceptance: —Solved by: 0

Statement

A photo gallery: 10 000 requests/s, 70 % of them images and static files. Object storage serves at most 5000 requests/s, so static traffic has to be caught closer to the user — in a CDN. A CDN serves 90 % of static requests itself. It may have two origins: object storage (for static) and a load balancer or app server for dynamic traffic. Writes cost 3× reads — pick the database tier accordingly.

Constraints

p95 ≤ 250 ms, errors ≤ 0.1 %, budget $2400/month, ≤ 5 instances per node.

Requirements

SimulationBuild from scratch

p95

≤ 250 ms

Errors

≤ 0.10 %

Budget

$2,400/mo

Users

2,000,000

Your architecture costs$0 / $2,400

★ within budget · ★★ ≤ 75 % · ★★★ ≤ 50 % of the budget

Scenarios (checked in order)

1GalleryLoad
10 000 requests/s for 60 seconds: 25 % reads, 5 % writes, 70 % static.
60 s · 10,000 rps · R 25 / W 5 / S 70 %

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