5.1.1 About Oracle VM

Oracle VM enables you to deploy the Oracle Linux operating system and application software within a supported virtualization environment.

If you use Oracle VM on Oracle Exadata Database Machine, then they provide CPU, memory, operating system, and sysadmin isolation for your workloads. You can combine VMs with network and I/O prioritization to achieve full stack isolation. For consolidation, you can create multiple trusted databases or pluggable databases in an Oracle VM, allowing resources to be shared more dynamically.

An Oracle VM environment consists of an Oracle VM Server, virtual machines, and resources. An Oracle VM Server is a managed virtualization environment providing a lightweight, secure, server platform which runs virtual machines, also known as domains.

Oracle VM Server is installed on a bare metal computer. The hypervisor present on each Oracle VM Server is an extremely small-footprint virtual machine manager and scheduler. It is designed so that it is the only fully privileged entity in the system. It controls only the most basic resources of the system, including CPU and memory usage, privilege checks, and hardware interrupts.

The hypervisor securely runs multiple virtual machines on one host computer. Each virtual machine runs in its own domain and has its own guest operating system. A primary management domain, dom0, an abbreviation for domain zero, also runs as a guest on top of the hypervisor. Dom0 has privileged access to the hardware and device drivers.

A user domain (domU) is an unprivileged domain that can access the InfiniBand HCA. the domU is started and managed on an Oracle VM Server by dom0. Because a domU operates independently of other domains, a configuration change applied to the virtual resources of a domU does not affect any other domains. A failure of the domU does not impact any other domains.

The terms "domain", "guest", and "virtual machine" are often used interchangeably, but they have subtle differences:

• A domain is a configurable set of resources, including memory, virtual CPUs, network devices and disk devices, in which virtual machines run.
• A domain or virtual machine is granted virtual resources and can be started, stopped and restarted independently of other domains or the host server itself.
• A guest is a virtualized operating system running within a domain. Guest operating systems each have their own management domain called a user domain, abbreviated to domU.

Up to 8 guests can run on the same Oracle VM Server, each within its own domain. These domains are unprivileged domains that can access the InfiniBand HCA. Each domU is started alongside dom0 running on Oracle VM Server. Other domains never interact with dom0 directly. Their requirements are handled by the hypervisor itself. Dom0 only provides a means to administer the hypervisor.

You use Oracle Exadata Deployment Assistant (OEDA) to create and configure Oracle VMs on Oracle Exadata Database Machine.