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Work · Fintech / Transaction Processing

Re-architecting a single-region system for high availability

Moving a fintech's core transaction processing off a single availability zone with no automated failover, onto a multi-AZ architecture with a measurable uptime SLO.

blueprint09 Jun 2026
$300K+
Average cost of one hour of downtime, mid-size/large enterprises
41%
Large enterprises reporting $1M-5M+ per hour of downtime
90%
Orgs requiring 99.99%+ ("five nines or near") uptime (ITIC reliability survey)

This is a solution blueprint — a reference architecture we can build for your business. The figures above are cited industry benchmarks for this class of system, not results claimed for a named client.

The pipeline we'd build

4 stages

Stage 01 · Multi-AZ

The workload is re-architected across multiple availability zones.

The challenge

A regional fintech ran core transaction processing on a single availability zone with no automated failover, exposing the business to the downtime costs ITIC's industry-wide survey finds are now the norm for enterprises this size.

What we did

We re-architect the workload across multiple availability zones with automated failover — health-checked DNS routing plus multi-AZ database replication — add chaos-engineering drills, and instrument full-stack observability with alerting tied to real error budgets.

The outcome

ITIC's 2024 downtime survey found the average cost of a single hour of downtime now tops $300,000 for over 90% of mid-size and large enterprises, with 41% reporting $1M-5M+ per hour — the exposure this re-architecture is built to close.

Stack

AWS (multi-AZ/multi-region)Kubernetes (EKS)TerraformAmazon AuroraDatadogRoute 53Redis

ITIC's Hourly Cost of Downtime Survey — one of the longest-running studies of its kind, polling over 1,000 firms — found the average cost of a single hour of downtime now exceeds $300,000 for more than 90% of mid-size and large enterprises, with 41% of large enterprises reporting $1M-5M+ per hour for the highest-stakes verticals like banking and transaction processing.

What a single-AZ failure actually costs

A single availability zone going down doesn't sound dramatic until it takes the whole transaction-processing system with it — no automated failover means every minute of the outage is billed at the full downtime-cost rate ITIC's survey documents, with no path to recovery except a manual, high-stress scramble.

The re-architecture, layer by layer

We re-architect the workload across multiple availability zones with automated failover — health-checked DNS routing plus multi-AZ database replication — add chaos-engineering drills, and instrument full-stack observability with alerting tied to real error budgets. The diagram below shows how the pieces fit together.

Multi-AZ high-availability architecture

Automated failover across availability zones — a blueprint of standard components, not a live deployment

Architecture
Edge / RoutingComputeDataObservability

Tap any component above for its role and the real tech.

A blueprint of standard multi-AZ components — adapted to whatever compute/database you already run, not a fixed template.

  1. Route 53 (API, Health-checked DNS failover): Routes traffic away from an unhealthy AZ automatically, no manual DNS change needed.
  2. EKS — AZ-A (Service, Kubernetes, pod disruption budgets): Primary compute, spread across nodes in this zone.
  3. EKS — AZ-B (Service, Kubernetes, pod disruption budgets): Standby capacity in a second zone, absorbing traffic on failover.
  4. Aurora (multi-AZ) (Data, Synchronous replication): Database replicates synchronously across zones so a failover loses no committed data.
  5. Redis cache (Data, Multi-AZ replication group): Session/cache layer, replicated so a zone failure doesn't cold-start the cache.
  6. Datadog + PagerDuty (Service, SLO-based alerting): Pages on error-budget burn, not on every noisy metric spike.

This pairs naturally with the delivery-pipeline discipline in our CI/CD modernization blueprint — a fast, safe deployment pipeline and a resilient runtime architecture solve different halves of the same reliability problem.

At a glance

Client

Solution blueprint

Sector

Fintech / Transaction Processing

Service

Cloud & DevOps

Kind

blueprint

Headline result

$300K+ · Average cost of one hour of downtime, mid-size/large enterprises

Handover

Documented, tested code in your repository

Questions we were asked

Is $300K/hour a realistic downtime cost, or an outlier?

ITIC's 2024 Hourly Cost of Downtime Survey — polling over 1,000 firms worldwide — found this is the average for over 90% of mid-size and large enterprises, not an outlier case. Costs concentrate even higher for banking, healthcare, and transaction-processing verticals specifically.

Does multi-AZ mean multi-region too?

Not necessarily — multi-AZ (spreading across data centers within one region) handles most availability failures at much lower cost and complexity than multi-region. We'd only recommend multi-region if the risk profile (e.g. an entire region going down) genuinely justifies the added cost.

How do you know the failover actually works before a real incident?

Chaos-engineering drills — deliberately triggering failures in a controlled way — verify the failover path under realistic conditions, rather than trusting it works because it looks correct on a architecture diagram.

Same problem, different business?

We'll send the architecture and a realistic timeline for your version of this — no obligation.

Request a blueprint