Multi-Cloud at Scale: Costs, Latency, and Real Numbers

The Network Cost Reality: Cross-cloud data transfer is expensive and measurable. Egress fees typically cost tens of dollars per terabyte. A pipeline moving 50 TB per day across clouds easily adds over $1,000 per month just in network charges. This is not an optimization problem, it is an architectural constraint that shapes every design decision. At scale, these costs compound. A company processing 500 TB monthly across three cloud providers might pay $15,000 to $25,000 in egress alone, separate from compute and storage. This is why modern architectures emphasize processing data close to its source and only moving aggregated or filtered results across cloud boundaries. Latency Between Clouds: Network round-trip time between cloud providers within the same continent typically ranges from 5 to 20 milliseconds. This makes strongly consistent, synchronous cross-cloud writes problematic without sacrificing tail latency. Cross-region writes within a single cloud might add 10 ms. Cross-cloud writes can add 30 to 50 ms or more. Many architectures choose eventual consistency at the integration layer to preserve reasonable p99 latencies. You accept 2 to 5 seconds of propagation delay rather than adding 40+ ms to every write operation. For analytics workloads, this trade-off is obvious. For operational systems like inventory management or payment processing, you often keep writes local to a single cloud and replicate asynchronously. Operational Complexity: Single-provider platforms offer end-to-end integration with one billing model, one Identity and Access Management (IAM) system, and integrated monitoring. Multi-cloud forces you to build or adopt your own catalog, governance plane, and observability that works across providers. You need unified monitoring that aggregates metrics like throughput, lag, error rate, and cost per gigabyte from multiple clouds. Operators run anomaly detection on these signals to trigger self-healing: scaling workers, rerouting around unhealthy regions, or temporarily degrading less critical pipelines during load spikes. When It Makes Sense: Companies accept this complexity for risk management, vendor diversification, regulatory constraints requiring local processing in multiple jurisdictions, or taking advantage of specialized services. The calculation is whether flexibility and resilience outweigh the measurable costs in dollars and operational effort.