Physical Architecture Concepts
Understand these components of OCI before you get started.
Oracle Cloud Infrastructure is physically hosted in regions and availability domains. A region is a localized geographic area, and an availability domain is one or more data centers located within a region. Oracle cloud regions are globally distributed data centers that provide secure, high-performance, local environments. These regions allow businesses to move, build, and run all workloads in the cloud from infrastructure to applications, while meeting regional data regulations. For more information about each offering, see Regions and Availability Domains and Dedicated Regions.
Availability Domains
Availability domains are isolated from each other, fault tolerant, and very unlikely to fail simultaneously or be impacted by the failure of another availability domain. When you configure your cloud services, use multiple availability domains to ensure high availability and to protect against resource failure. Be aware that some resources must be created within the same availability domain, such as an instance and the storage volume attached to it. For more details, see About Regions and Availability Domains.
Fault Domains
A fault domain is a grouping of hardware and infrastructure within
an availability domain. Each availability domain contains three fault domains. Fault
domains provide anti-affinity: they let you distribute your instances so that the
instances are not on the same physical hardware within a single availability domain. A
hardware failure or Compute hardware maintenance event that affects one fault domain
does not affect instances in other fault domains.
Realms
A realm is a logical collection of regions. Realms are isolated from each other and do not share any data. Your tenancy exists in a single realm and has access to the regions that belong to that realm. OCI currently offers realms for commercial regions, government regions, and dedicated regions.
