This topic describes the physical and logical organization of Oracle Cloud Infrastructure resources.
Oracle Cloud Infrastructure is 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. A region is composed of one or more availability domains. Most Oracle Cloud Infrastructure resources are either region-specific, such as a virtual cloud network, or availability domain-specific, such as a compute instance. Traffic between availability domains and between regions is encrypted. Availability domains are isolated from each other, fault tolerant, and very unlikely to fail simultaneously. Because availability domains do not share infrastructure such as power or cooling, or the internal availability domain network, a failure at one availability domain within a region is unlikely to impact the availability of the others within the same region. The availability domains within the same region are connected to each other by a low latency, high bandwidth network, which makes it possible for you to provide high-availability connectivity to the internet and on-premises, and to build replicated systems in multiple availability domains for both high-availability and disaster recovery. Oracle is adding multiple cloud regions around the world to provide local access to cloud resources for our customers. To accomplish this quickly, we’ve chosen to launch regions in new geographies with one availability domain. As regions require expansion, we have the option to add capacity to existing availability domains, to add additional availability domains to an existing region, or to build a new region. The expansion approach in a particular scenario is based on customer requirements as well as considerations of regional demand patterns and resource availability. For any region with one availability domain, a second availability domain or region in the same country or geo-political area will be made available within a year to enable further options for disaster recovery that support customer requirements for data residency where they exist. Regions are independent of other regions and can be separated by vast distances—across countries or even continents. Generally, you would deploy an application in the region where it is most heavily used, because using nearby resources is faster than using distant resources. However, you can also deploy applications in different regions for these reasons:
Regions are grouped into realms . Your tenancy exists in a single realm and can access all regions that belong to that realm. You cannot access regions that are not in your realm. Currently, Oracle Cloud Infrastructure has multiple realms. There is one commercial realm. There are multiple realms for Government Cloud: US Government Cloud FedRAMP authorized and IL5 authorized, and United Kingdom Government Cloud. The following table lists the regions in the Oracle Cloud Infrastructure commercial realm :
To subscribe to a region, see Managing Regions. For a list of regions in the the Oracle Government Cloud realms, see the following topics: Note Your Tenancy's Availability Domain Names Oracle Cloud Infrastructure randomizes the availability domains by tenancy to help balance capacity in the data centers. For example, the availability domain labeled PHX-AD-1 for tenancyA may be a different data center than the one labeled PHX-AD-1 for tenancyB. To keep track of which availability domain corresponds to which data center for each tenancy, Oracle Cloud Infrastructure uses tenancy-specific prefixes for the availability domain names. For example: the availability domains for your tenancy are something like Uocm:PHX-AD-1, Uocm:PHX-AD-2, and so on. To get the specific names of your tenancy's availability domains, use the ListAvailabilityDomains operation, which is available in the IAM API. You can also see the names when you use the Console to launch an instance and choose which availability domain to launch the instance in.
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. To control the placement of your compute instances, bare metal DB system instances, or virtual machine DB system instances, you can optionally specify the fault domain for a new instance or instance pool at launch time. If you don't specify the fault domain, the system selects one for you. Oracle Cloud Infrastructure makes a best-effort anti-affinity placement across different fault domains, while optimizing for available capacity in the availability domain. To change the fault domain for a compute instance, edit the fault domain. To change the fault domain for a bare metal or virtual machine DB system instance, terminate it and launch a new instance in the preferred fault domain. Use fault domains to do the following things:
For more information:
Trial, free tier, and pay-as-you-go tenancies are limited to one subscribed region. You can request an increase to the limit for pay-as-you-go tenancies, see To request a subscribed region limit increase for more information. Universal monthly credit tenancies can subscribe to all publicly released commercial regions. You can submit a request to increase the subscribed region count for your tenancies from within the Console. If you try to subscribe to a region beyond the limit for your tenancy, you'll be prompted to submit a limit increase request. Additionally, you can launch the request from the service limits page or at any time by clicking the link under the Help menu ().
All Oracle Cloud Infrastructure regions offer core infrastructure services, including the following:
Generally available cloud services beyond those in the previous list are made available based on regional customer demand. Any service can be made available within a maximum of three months, with many services deploying more quickly. New cloud services are made available in regions as quickly as possible based on a variety of considerations, including regional customer demand, ability to achieve regulatory compliance where applicable, resource availability, and other factors. Because of Oracle Cloud Infrastructure's low latency interconnect backbone, you can use cloud services in other geographic regions with effective results when those services are not available in your home region, as long as data residency requirements do not prevent you from doing so. We regularly work with customers to help ensure effective access to required services.
The following sections list the resource types based on their availability: across regions, within a single region, or within a single availability domain. Tip In general: IAM resources are cross-region. DB Systems, instances, and volumes are specific to an availability domain. Everything else is regional. Exception: Subnets were originally designed to be specific to an availability domain. Now, you can create regional subnets, which are what Oracle recommends.
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