Why it matters
OCI is smaller than the big three but growing in specific niches: Oracle Database workloads, HPC, and cost-sensitive deployments. Understanding it matters for multi-cloud strategy conversations.
The architecture
OCI resources belong to compartments — logical containers similar to GCP folders/projects. Compartments nest hierarchically and are the boundary for IAM policies.
A tenancy is the OCI equivalent of an AWS account or GCP organization. It contains compartments, users, groups, and all resources.
How it works end to end
Regions and availability domains: regions have 1-3 availability domains (like AZs). Multi-AD regions enable HA; single-AD regions are common in smaller markets.
Core services: Compute (VMs and bare metal), Object Storage, Block Volumes, VCN (networking), Autonomous Database (Oracle DB self-driving), Kubernetes Engine (OKE).
OCI's pricing model is often simpler than AWS: 10 TB/month free egress, per-second billing on compute, cheaper bare metal.