Regions

Localized geographical areas,comprised of one or more Availability Domain (AD).

Availability Domain

    One or more Fault-tolerant, isolated data center located within the region, but connected to each other by a low latency, high bandwidth network.
    Availability Domains are isolated from each other, fault tolerant, and very unlikely to fail simultaneously.    Because Availability Domains do not share physical infrastructure, such as power or cooling, or the internal availability domain network, a failure that impacts one AD is unlikely to impact the availability of the others.

Fault Domain

    Grouping of hardware and infrastructure within an Availability Domain to provide anti- affinity (logical data center).    Each Availability Domain  has 3 Fault Domains (FD)
    FDs act as a logical data center within an AD. Usage of multiple FDs reducers correlation of failures within an AD.

One AD Region

    Oracle Cloud Infrastructure has chosen to launch regions in new geographies with one AD ( to increase global reach quickly).
    For any region with one Ad, a second AD or region in the same country or geo-political are will be made available within a year to enable further options for DR and data residency