Calculator inputs
Use this planner to compare recovery timing, failover capacity, replication exposure, and readiness scoring across several cloud continuity designs.
Example data table
| Architecture | Nodes | Peak demand | Usable failover capacity | Expected RTO | Estimated RPO | Readiness score |
|---|---|---|---|---|---|---|
| Active-Passive | 4 + 2 | 1620 CU | 800 CU | 240 sec | 20 sec | 78 |
| Warm Standby | 5 + 2 | 1755 CU | 700 CU | 265 sec | 25 sec | 74 |
| Active-Active | 6 + 2 | 1890 CU | 1216 CU | 155 sec | 15 sec | 91 |
CU means capacity units. Adjust the unit definition to match vCPU, requests per second, throughput, or another internal planning baseline.
Formula used
1) Peak failover demand
Peak Failover Demand = Required Workload Capacity × Peak Load Multiplier
2) Usable failover capacity
Active-Passive = Standby Nodes × Node Capacity
Warm Standby = Standby Nodes × Node Capacity × Warm Readiness %
Active-Active = Total Cluster Capacity × (1 − Average Utilization %)
N+1 = Reserve Nodes × Node Capacity
3) Failure detection time
Detection Time = Health Check Interval × Missed Checks
4) Automatic recovery path
Automatic RTO = Detection Time + Orchestration Time + Warmup Time + DNS TTL
5) Expected RTO
Expected RTO = (Automatic RTO × Automation Success Probability) + (Manual Intervention Time × Failure Probability)
6) Estimated RPO
Estimated RPO = Replication Lag
7) Annual downtime and cost
Annual Downtime Minutes = Annual Failover Events × Expected RTO ÷ 60
Annual Downtime Cost = Annual Downtime Hours × Downtime Cost per Hour
8) Readiness score
Readiness Score = Weighted blend of capacity, RTO, RPO, availability, automation, and testing metrics.
The scoring model is a planning aid, not a compliance certification. Use it to compare design options and identify weak failover assumptions quickly.
How to use this calculator
- Choose the architecture that best matches your deployment pattern.
- Enter normal workload capacity and expected peak multiplier.
- Add primary and standby node counts with per-node capacity.
- Provide timing assumptions for detection, orchestration, warmup, and routing.
- Enter replication lag, automation success, and failover test success.
- Set business targets for RTO, RPO, availability, and downtime cost.
- Submit the form to review readiness score, timing, capacity, and annualized impact.
- Export CSV or PDF to share the scenario with operations or leadership teams.
Frequently asked questions
1) What does this calculator estimate?
It estimates failover capacity coverage, expected recovery time, replication exposure, projected availability, annual downtime cost, and an overall readiness score.
2) What is the difference between RTO and RPO?
RTO measures how long service recovery takes. RPO measures how much recent data could be lost because replication or synchronization is behind.
3) Why does active-active use utilization in the formula?
Active-active designs rely on spare headroom across live nodes. If utilization is already high, less capacity remains available to absorb a zone or site failure.
4) Why include manual intervention time?
Automation is never perfect. Manual intervention time helps model the expected recovery delay when scripts, orchestration, or dependency checks fail during a real incident.
5) Is the readiness score an industry standard?
No. It is a weighted planning score for internal comparison. It helps rank scenarios, but it does not replace operational testing or architecture review.
6) What unit should capacity use?
Use any consistent unit, such as vCPU-equivalent, requests per second, transactions per minute, or throughput units. The comparison remains valid if every field uses the same basis.
7) Can this model support cloud regions or availability zones?
Yes. Treat each region or zone as part of your primary and standby design. Enter timing and capacity assumptions that reflect the architecture being reviewed.
8) Why export the results?
Exports make it easier to document assumptions, compare several failover strategies, attach evidence to planning reviews, and share results with engineering stakeholders.