Which two are valid mechanisms for accessing OS-level metrics on a Base Database Service Virtual Machine?

The Oracle Cloud Agent, which is installed and enabled by default on Base Database Service Virtual Machines, includes a Monitoring plugin. This plugin automatically collects OS-level performance metrics such as CPU utilization, memory utilization, and network traffic. These metrics are published to the Oracle Cloud Infrastructure (OCI) Monitoring service. Once in the Monitoring service, these metrics can be accessed in two primary ways: visually through the Metrics Explorer in the OCI Console, or programmatically via the OCI Monitoring service's REST APIs and SDKs.

A. The vmcli utility is used for lifecycle management of virtual machines on Exadata Cloud Infrastructure, not for retrieving OS performance metrics on Base Database Service.
C. A custom agent is a possible option but not the only way; OCI provides a native, default mechanism via the Oracle Cloud Agent for OS metric collection.
D. Metrics for a Base Database Service are associated with the Database service itself, not the Cloud Exadata Service, which is a distinct and separate offering.

1. Oracle Cloud Infrastructure Documentation, Base Database Service, Monitoring a DB System: "To monitor the health, capacity, and performance of your DB systems, the Oracle Cloud Infrastructure Monitoring service collects metrics from the DB system... The metrics... are automatically available for any DB system you create. You do not need to enable monitoring on the resource to get these metrics." This section lists OS metrics like CpuUtilization and MemoryUtilization.

(Reference: Oracle Cloud Infrastructure Documentation > Database > Base Database > Monitoring a DB System > Available Metrics: Base Database Service)

2. Oracle Cloud Infrastructure Documentation, Monitoring, Viewing Metric Charts in Metrics Explorer: "Use Metrics Explorer to build queries and create charts for monitoring your resources... The Oracle Cloud Agent collects metrics from DB systems." This confirms that metrics collected by the agent are viewable in the Metrics Explorer.

(Reference: Oracle Cloud Infrastructure Documentation > Observability & Management > Monitoring > Viewing Metric Charts in Metrics Explorer)

3. Oracle Cloud Infrastructure Documentation, Monitoring, Monitoring API: "Use these API operations to manage the Monitoring service... For example, you can retrieve metric data points by calling the SummarizeMetricsData operation." This confirms programmatic access to the metrics collected by the service.

(Reference: Oracle Cloud Infrastructure Documentation > Observability & Management > Monitoring > API Reference and Endpoints > Monitoring API)

4. Oracle Cloud Infrastructure Documentation, Exadata Cloud Service, vmcli Command Reference: The documentation for the vmcli utility shows commands for managing VM lifecycle (create, delete, list, start, stop) and associated resources, with no commands for querying OS performance metrics.

(Reference: Oracle Cloud Infrastructure Documentation > Exadata Cloud Service > Reference > vmcli Command Reference)