The Virtualization Model
One model can be used for virtualization technologies, such as Software Defined Compute (SDC), Software Defined Networking (SDN), and Software Defined Storage (SDS), as shown in the picture below.
The model shows 3 layers: at the bottom, physical devices, then a virtualization layer that creates abstract system resources, and at the top a number of virtual devices that are compiled using the abstract system resources. It is a well-known way of implementing a virtual machine environment, but it also applies to networking and storage.
When the virtualization layer is programmable, using APIs, it can be controlled by (external, third party) software, to support software defined computing, software defined storage, or software defined networking.
The number of physical devices is typically independent of the number of virtual devices. The physical devices can be commodity hardware, or enterprise grade hardware, or a mixture. Because of the virtualization layer the physical hardware can be upgraded, replaced or phased out independent of the operation of the virtual devices.
The virtualization layer provides a resource pool that enables virtual devices to be configured. Ideally, the virtualization layer should decrease the performance, as delivered by the physical devices, by no than 10%.
The virtualization layer can provide advanced features, such as:
- Storage (SDS): deduplication, RAID, Snapshots;
- Compute (SDC): Live migration, virus scanning;
- Networking (SDN): VLANs, filtering, IDS, firewalls, virus scanning;
and provides APIs for scripting (orchestration), as provided by software such as OpenStack.
This entry was posted on Thursday 23 April 2015