Why it matters
Multi-cloud done wrong is expensive and slow. Done right in the specific scenarios where it helps, it can be transformative. The goal is clarity on which scenario you're in.
The architecture
Regulatory / sovereignty: some workloads must run in specific clouds to comply with regulations (public sector requiring national cloud, healthcare requiring specific certifications). Genuine multi-cloud driver.
Resilience: distributing across clouds for cloud-level outage protection. Rare in practice because most outages are regional, not cloud-wide.
Negotiation: leverage in contract negotiation. Real but subtle benefit.
How it works end to end
Best-of-breed: use each cloud for what it does best. BigQuery on GCP, Bedrock on AWS, Oracle DB on OCI. This is technically multi-cloud but strategically single-purpose per cloud.
Portability approaches: use Kubernetes, Terraform, Cloud Foundry to abstract cloud specifics. Reduces lock-in but adds complexity.
Data gravity: moving data between clouds is expensive and slow. Design data locality carefully.