1. Concepts Guide
  2. Architecture and Design
  3. Layered Architecture

Layered Architecture

For the architecture of Oracle Private Cloud Appliance a layered approach is taken. At the foundation are the hardware components, on which the core platform is built. This, in turn, provides a framework for administrative and operational services exposed to different user groups. The layers are integrated but not monolithic: they can be further developed at different rates as long as they maintain compatibility. For instance, supporting a new type of server hardware or extending storage functionality are enhancements that can be applied separately, and without redeploying the entire controller software stack.

Hardware Layer

The hardware layer contains all physical system components and their firmware and operating systems.

  • The three management nodes form a cluster that runs the base environment for the controller software.

  • The compute nodes provide the processing capacity to host compute instances.

  • The storage appliance provides disk space for storage resources used by compute instances. It also provides the storage space required by the appliance internally for its operation.

  • The network switches provide the physical connections between all components and the uplinks to the public (data center) network.

Platform Layer

Private Cloud Appliance uses a service-based deployment model. The product is divided into functional areas that run as services; each one within its own container. The platform provides the base for this model. Leveraging the capabilities of Oracle Cloud Native Environment, the management node cluster orchestrates the deployment of the containerized services, for which it also hosts the image registry.

In addition, the platform offers a number of fundamental services of its own, that are required by all other services: message transport, secrets management, database access, logging, monitoring, and so on. These fundamental services are standardized so that all services deployed on top of the platform can plug into them in the same way, which makes new service integrations easier and faster.

The platform also plays a central role in hardware administration, managing the data exchange between the hardware layer and the services. Information about the hardware layer, and any changes made to it, must be communicated to the services layer to keep the inventory up-to-date. When operations are performed at the service layer, an interface is required to pass down commands to the hardware. For this purpose, the platform has a tightly secured API that is only exposed internally and requires the highest privileges. This API interacts with management interfaces such as the server ILOMs and the storage controllers, as well as the inventory database and container orchestration tools.

For additional information about this layer in the appliance architecture, refer to Platform Layer Overview.

Infrastructure Services Layer

This layer contains all the services deployed on top of the platform. They form two functionally distinct groups: user-level cloud services and administrative services.

Cloud services offer functionality to users of the cloud environment, and are very similar in operation to the corresponding Oracle Cloud Infrastructure services. They constitute the Compute Enclave, and enable the deployment of customer workloads through compute instances and associated resources. Cloud services include the compute and storage services, identity and access management, and networking.

The administrative services are either internal or restricted to administrators of the appliance. These enable the operation of the cloud services and provide support for them. They constitute the Service Enclave. Administrator operations include system initialization, compute node provisioning, capacity expansion, tenancy management, upgrade, and so on. These operations have no externalized equivalent in Oracle Cloud Infrastructure, where Oracle fulfills the role of the infrastructure administrator.