OCI – Oracle Cloud Infrastructure –
A Brief about Region, AD – Availability Domain and FD – Fault Domain
Oracle Cloud Infrastructure comprises regions which are localized geographic areas composed of one or more Availability Domain. And each Availability Domain is composed of three Fault Domains. An Availability Domain comprises one or more Data Centers located within a region. Availability Domains are Isolated each other. They are fault tolerant and unlikely to fail simultaneously. This is because Availability Domain don’t share Physical Infrastructure like Power, Cooling or the Internal Availability Domain Network.
A Fault Domain is a grouping of Hardware and Infrastructure within an Availability Domain. Each Availability Domain contains three Fault Domains. Fault Domains let you distribute instances so that they are not on the same physical hardware within a single Availability Domain. So an unexpected hardware failure or compute hardware maintenance that affects one fault domain does not affect instances in other fault domains.