9.6.21 Oracle Exadata Virtual Machines
Consolidated environments can now use Oracle Virtual Machine (Oracle VM) on X5-2, X4-2, X3-2, and X2-2 database servers to deliver higher levels of isolation between workloads. Virtual machine isolation is desirable for workloads that cannot be trusted to restrict their security, CPU, or memory usage in a shared environment. Examples are hosted or cloud environments, cross department consolidation, test and development environments, and non-database or third party applications running on a database machine. Oracle VM can also be used to consolidate workloads that require different versions of clusterware, for example SAP applications that require specific clusterware patches and versions.
The higher isolation provided by virtual machines comes at the cost of increased resource usage, management, and patching because a separate operating system, clusterware, and database install is needed for each virtual machine. Therefore it is desirable to blend Oracle VM with database native consolidation by consolidating multiple trusted databases within a virtual machine. Oracle Resource Manager can be used to control CPU, memory, and I/O usage for the databases within a virtual machine. The Oracle Multitenant option can be used to provide the highest level of consolidation and agility for consolidated Oracle databases.
Exadata Virtual Machines use high speed InfiniBand networking with Single Root I/O Virtualization (SR-IOV) to ensure that performance within a virtual machine is similar to Exadata's famous raw hardware performance. Exadata Smart Scans greatly decrease virtualization overhead compared to other platforms by dramatically reducing message traffic to virtual machines. Exadata Virtual Machines can dynamically expand or shrink CPUs and memory based on the workload requirement of the applications running in that virtual machine.
Virtual machines on Exadata are considered Trusted Partitions, and therefore software can be licensed at the virtual machine level instead of the physical processor level. Without Trusted Partitions, database options and other Oracle software must to be licensed at a server or cluster level even though all databases running on that server or cluster may not require a particular option.