Kill the single points of failure

beginner

Scenario & brief

This service runs a single app instance and a single database in one AZ, with no backups. It works — until anything fails.

Targets: 99.95% availability, critical durability, p99 ≤ 200 ms, under $1,200/mo. The latency budget is generous — this one is about resilience, not raw speed.

2,000 rps peakp99 ≤ 200ms99.95% availdurability: criticalbudget $1,200/mo

App Servers

Compute

Instance class

Scaling

Instances (static)

1instances

Availability Zones

Purchasing

System health

Erupting · SLA breach

/ 100

Score

SLA not met yet

Monthly cost

$653

Budget $1,200/mo · within budget

Metrics

Capacity100

Availability30

Durability25

Cost efficiency78

Requirements

Peak capacity — 3600 rps compute · 3400 rps db (need ≥ 2000 rps)
p99 latency — ~77 ms (need ≤ 200 ms)
Availability — 99.00% (need ≥ 99.95%)
Durability — at risk (need redundancy + backups)
Budget — $653/mo (need ≤ $1200/mo)

Advisor

Compute runs in a single AZ — spread across ≥2 AZs (with ≥2 instances) to meet the availability target.
A single instance is a single point of failure — run at least two.
The database has no Multi-AZ standby or replica — a failure risks data loss. Enable Multi-AZ and backups.

Discussion

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For learning purposes only. Costs and capacities are illustrative, not live AWS prices. Not affiliated with or endorsed by Amazon Web Services.