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A cloud vendor provides a complete pack of tools and services to build and manage your cloud. Each cloud forms an infrastructure with all the cloud services designed and arranged for a seamless data flow. In this blog, we cover all about Oracle Cloud Infrastructure Fundamentals.
This blog covers the following topics.
Oracle Cloud Infrastructure Fundamentals
Oracle Cloud Infrastructure is the web of cloud services that enable businesses to build and run various cloud applications. Oracle provides a high availability environment to run your applications with high performance compute and storage services. There are many services that Oracle gives a business to manage their cloud seamlessly, like Analytics cloud, API Gateway, Storage, Big Data, Cloud Advisor, Data Integration, Data Science, Load Balancing, and many more.
Complete Oracle Cloud Infrastructure works on the three parameters Availability Region, Availability Domain and Fault Domain.

OCI Availability Region (AR)
Availability Regions are the geographical area where Oracle cloud has set up its data centre. Oracle has currently 23 regions available globally and is building more. More regions result in better disaster recovery. If one gets down due to any natural hazard, the other will be available.
In Oracle, there are two types of Regions:
- Government – It is for government use and is accessible only by government officials and restricted to rest.
- Commercial – It is publicly available that is any business and organization can use it.
Read More: OCI Regions
OCI Availability Domain (AD)
Availability Domains are the data centre that lies in a region. These data centre are the units that stores all the data in the enormous machines. It contains all the hardware like storage, computes servers, network connectivity, etc., by which Oracle provides all the services. Up to three data availability domains can be present in one region connected with low latency and high bandwidth networks.
Features of Availability Domains
- All Availability Domains within a region are isolated and independent from each other.
- No hardware is shared between Availability Domains within a region.
- Fault-Tolerant and unlikely to be down at the same time.
OCI Fault Domain (FD)
Fault Domains are the logical data centre that lies in an Availability Domain. In other words, it is a grouping of hardware and infrastructure within the availability domain. Fault domain helps in hardware maintenance or failure and adds one more layer of protection.
Features of Fault Domains
- Act as a logical data centre by grouping hardware within Availability Domain.
- Use of multiple Fault Domain within Availability Domain reduces correlation of failures.
- Other Fault Domains get into use in power failure or maintenance.
- Each Availability Domain has up to 3 Fault Domains.
Also Check: Our blog post on Oracle Cloud Support.
Designing OCI Architecture
There can be multiple structure designs for an Oracle Cloud Infrastructure Architecture. Two types of architecture designs with one Single Region are:
- Single Availability Domain
- Multiple Availability Domain
Single Region – Single Availability Domain (AD)

The above image is of the single Region and single Availability Domain Oracle architecture. It contains one availability domain bounded by one region. There are three fault domains present inside the availability domain.
Scenario for this Design
- Everything, including the availability and fault domains, will be down if the entire region is down. But an entire region can not be down, so this case is most unlikely to happen.
- If the availability domain is down, the complete data centre will be down, including all fault domains. It can happen in rare cases when the complete availability domain is under maintenance.
- If any fault domain is down, then other co-existing fault domains will become active.
Read More: About oci tenancy.
Single Region – Multiple Availability Domain (AD)

This diagram is for Single Region with multiple availability domains. It features one region containing two availability domains. There are three fault domains present inside each availability domain.
Scenario for this Design
- If the entire region is down, then both availability domains will also be down. But this case is unlikely to happen as the entire region can not be down.
- If one availability domain is down, all the fault domains present inside it will be down, but another availability domain will be present to handle the same work.
- If any fault domain is down from both availability domains, other co-existing fault domains will become active.
Conclusion
Oracle Cloud Infrastructure is one of the oldest running cloud vendors and provides various services to handle your workload. We covered all the Oracle Cloud Infrastructure Fundamentals in this blog and concluded that more regions, availability domains, and fault domains are preferred while designing an infrastructure. But an organization can design its infrastructure based on the needs and budget.
Related/References
- Oracle Cloud Infrastructure: Everything You Need to Know
- What is Region, AD, FD and Realm in OCI
- Oracle Cloud Infrastructure (OCI) Architect Live Training
- Oracle Cloud Infrastructure Architect: Step-By-Step Activity Guides
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