Explanation
There are two types of DB systems on virtual machines:
A 1-node virtual machine DB system consists of one virtual machine.
A 2-node virtual machine DB system consists of two virtual machines. (RAC) A virtual machine DB system database uses Oracle Cloud Infrastructure block storage instead of local storage.You specify a storage size when you launch the DB system, and you can scale up the storage as needed at any time.
For 1-node virtual machine DB systems, Oracle Cloud Infrastructure provides have a "fast provisioning" option that allows you to create your DB system using Logical Volume Manager as your storage management software.
Oracle CloudInfrastructure offers single-node DB systems on either bare metal or virtual machines, and
2-node RAC DB systems on virtual machines. If you need to provision a DB system for development or testing purposes, then a special fast provisioning single-node virtual machine system is available.
You can manage these systems by using the Console, the API, the Oracle Cloud Infrastructure CLI, the Database CLI (DBCLI), Enterprise Manager, Enterprise Manager Express, or SQL Developer.

Reference: https://www.oracle.com/a/ocom/docs/best-practices-for-iam-on-oci.pdf

Explanation
Oracle Cloud Infrastructure FastConnect provides an easy way to create a dedicated, private connectionbetween your data center and Oracle Cloud Infrastructure. FastConnect provides higher-bandwidth options, and a more reliable and consistent networking experience compared to internet-based connections.