Pick the right DynamoDB mode

advanced

Scenario & brief

This table sees flat traffic that briefly spikes to 12,000 rps. It's on provisioned capacity sized far below the spike, so writes throttle exactly when it matters. Cranking provisioned units high enough to cover the spike would mean paying for that ceiling 24×7.

Targets: p99 ≤ 130 ms, 99.95% availability, critical durability, under $700/mo.

For spiky, unpredictable load, on-demand capacity is the fit — it absorbs the spike with no throttling and you only pay for what you use. Pair it with an autoscaling compute tier across two AZs.

12,000 rps peakp99 ≤ 130ms99.95% availdurability: criticalbudget $700/mo

App Servers

Compute

Instance class

Scaling

Instances (static)

3instances

Availability Zones

Purchasing

System health

Erupting · SLA breach

/ 100

Score

SLA not met yet

Monthly cost

$899

Budget $700/mo · $199 over

Metrics

Capacity40

Availability50

Durability100

Cost efficiency43

Requirements

Peak capacity — 10800 rps compute · 4800 rps db (need ≥ 12000 rps)
p99 latency — ~185 ms (need ≤ 130 ms)
Availability — 99.50% (need ≥ 99.95%)
Durability — protected (need redundancy + backups)
Budget — $899/mo (need ≤ $700/mo)

Advisor

Compute tops out at ~10800 rps but peak demand is 12000 rps — requests will queue.
The database is saturated at peak — add a cache to shed read load, or scale it up.
Compute runs in a single AZ — spread across ≥2 AZs (with ≥2 instances) to meet the availability target.

Discussion

No comments yet. Be the first to start the discussion.

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