OCI Architecture

Core components of Oracle Cloud Infrastructure’s (OCI) physical architecture. The first element is regions, which are localized geographic areas that contain one or more availability domains. Availability domains are fault tolerant data centers within a region that are connected by a low latency, high bandwidth network. Fault domains, on the other hand, are groupings of hardware and infrastructure within an availability domain that provide anti-affinity, essentially serving as logical data centers.

When selecting a region for your cloud resources, there are several key factors to consider. The first is location, as you should choose a region that is close to your users in order to achieve the lowest latency and highest performance. The second factor is data residency and compliance requirements, as many countries have strict rules regarding where data must be stored and processed. Finally, you should consider service availability, as new services are often made available in certain regions based on demand, regulatory compliance, and resource availability.

Availability domains are isolated from each other and are resistant to simultaneous failure. This is because they do not share physical infrastructure, such as power or cooling, or the internal network. Therefore, a failure in one availability domain is unlikely to affect the availability of others. Within each availability domain, there are three fault domains, which serve as logical data centers. By placing resources in different fault domains, you can ensure that they do not share a single point of hardware failure, such as physical servers or power distribution units. This helps to increase overall availability.

When designing your own OCI architecture, it is important to consider fault domains and availability domains to avoid single points of failure. Oracle ensures that servers and other hardware are redundant to minimize hardware failures, and you should do the same in your own design. One way to do this is to use software-defined virtual networks to create compartmentalized environments for your resources, and to use multiple fault domains to ensure that your resources are

Sample Questions:

    1. Which statement is true about OCI architecture?
    • [] Availability domains share infrastructure such as power, cooling, or internal availability domain network within a region.
    • [] An availability domain is a logical data center.
    • [] A single fault domain has multiple availability domains within a region.
    • An OCI region is a localized geographic area.
    1. Which OCI construct protects against failures within an availability domain?
    • Fault Domain
    • [] Load Balancer
    • [] Regions
    • [] Tenancy
    • [] Compartments
    1. Which statement is true about OCI architecture and its core components?
    • Each availability domain has three fault domains.
    • [] All OCI regions have three availability domains.
    • [] Each fault domain has three availability domains.
    • [] Fault domains act as physical data centers within an availability domain.
    1. Which two statements are true about OCI Regions?
    • [] An OCI region cannot have more than one availability domain.
    • It’s a localized geographic area having one or more Availability Domains.
    • [] All OCI regions have three availability domains.
    • [] OCI Regions are a collection of logical data centers.
    • There is a home region for your OCI Tenancy.
    1. You have subscribed to an OCI region, which has one availability domain. You want to deploy a highly available application with two web servers and a 2-Node database.
    • [] How would you place the components to maintain high availability of the application?
    • [] Place the servers in one fault domain and the database nodes in another fault domain.
    • [] Place all the components in the same fault domain.
    • High availability is not possible because there is only one availability domain in the region.
    • Place one server and a DB node in one fault domain, and the second server and second DB node in another fault domain.


  • OCI Architecture includes regions, availability domains, fault domains, and compartments
  • When selecting a region, consider location, data residency and compliance requirements, and service availability
  • Availability domains are isolated, fault tolerant data centers within a region
  • Fault domains are groupings of hardware and infrastructure within an availability domain that provide anti-affinity
  • To increase availability, place resources in different fault domains to avoid single points of hardware failure
  • In OCI, resources in one fault domain are being actively changed at any given time to isolate availability problems caused by change procedures
  • Compartments are logical collections of related resources that can be nested up to six levels and are used to isolate and control access to resources
  • Compartments can have resources added or removed, and can interact with resources in different compartments
  • Budgets can be assigned to resources in compartments

Basic Concepts:

  • The key benefit of using Oracle Cloud Infrastructure (OCI) is its committed performance with a predictable pricing model.
  • In an Infrastructure as a Service (IaaS) offering, you are responsible for managing the operating system.
  • Horizontal scaling involves adding additional compute instances, while vertical scaling involves adding more CPU or memory to an existing server.
  • Scaling in OCI can involve scaling up or down, as well as scaling in or out.
  • Compartments are used to logically group and isolate OCI resources.
  • Groups are used to categorize multiple users into teams.
  • OCI Resource Manager leverages Terraform to configure infrastructure as code.
  • Fault domains protect against unexpected hardware or power supply failures within an availability domain.


  • The key benefit of OCI Virtual Machine DB Systems is support for RACDB systems, fast provisioning, and the ability to scale up block storage anytime.
  • Object storage (Standard) offers immediate retrieval storage.
  • OCI Archive Storage has the lowest pricing for storage.
  • File storage provides a shared file system across multiple compute instances.
  • Archive storage can be used to migrate old database backups from on-premises data centers to OCI.


  • OCI Exadata DB Systems are not available as part of the OCI Free Tier.
  • VM DB Systems offer managed Real Application Cluster (RAC) support.
  • Autonomous Data Warehouse (ADW) allows for scale-up of both CPU and storage without downtime.
  • Autonomous Transaction Processing (ATP) provides the best performance for running OLTP workloads.


  • The OCI Web Application Firewall is an edge service.
  • IPSec VPN can be used to establish a secure connection between an on-premises data center and OCI.
  • Oracle Data Safe can be used to assess the security of your databases.
  • The Dynamic Routing Gateway (DRG) enables OCI compute instances to connect to on-premises environments.
  • Fast Connect (1 Gbps public peering) is not part of OCI’s always free eligible resources.
  • OCI Fast Connect offers a dedicated connection with minimal network latency from on-premises data centers to OCI.

Support & Maintenance:

  • You cannot use My Oracle Support (MOS) to solve issues with Always Free resources in an OCI Free Trial account.
  • You are not required to register and log support requests in MOS for your account password.
  • Tags and compartments can be used to group and categorize expenses.
  • Cost Analysis does not include the ability to filter costs by application as a default feature.
  • Reserved instance pricing is not supported by OCI.
  • The OCI Compute service does not offer an application plane SLA.
  • Twitter notifications are not available to you when OCI creates or resolves an incident.
  • OCI usage reports are generated daily.
  • The Data Transfer Appliance can be used to move large amounts of data from on-premises to OCI.
  • Budgets can send alerts when you might exceed your spending threshold.
  • Reliability is not covered by the OCI SLA.