In computing, a storage hypervisor is a portable software program that runs on a physical hardware platform, on a virtual machine, inside a hypervisor OS or in all three places. It may co-reside with virtual machine supervisors or have exclusive control of its platform. The portable nature of the storage hypervisor software refers to its flexibility to run on on virtual machine or be hosted on many different platforms in a hardware independent manner similar to virtual server hypervisors.[1]
The storage hypervisor, a centrally-managed supervisory software program, provides a comprehensive set of storage control and monitoring functions that operate as a transparent virtual layer across consolidated disk pools to improve their availability, speed and utilization.
Storage hypervisors enhance the combined value of multiple disk storage systems, including dissimilar and incompatible models, by supplementing their individual capabilities with extended provisioning, data protection, replication and performance acceleration services.
In contrast to embedded software or disk controller firmware confined to a packaged storage system or appliance, the storage hypervisor and its functionality spans different models and brands and types of storage [including SSD (solid state disks), SAN (storage area network) and DAS (direct attached storage) and Unified Storage(SAN and NAS)] covering a wide range of price and performance characteristics or tiers. The underlying devices need not be explicitly integrated with each other nor bundled together.
A storage hypervisor enables hardware interchangeability. The storage hardware underlying a storage hypervisor matters only in a generic way with regard to performance and capacity. While underlying "features" may be passed through the hypervisor, the benefits of a storage hypervisor underline its ability to present uniform virtual devices and services from dissimilar and incompatible hardware, thus making these devices interchangeable. Continuous replacement and substitution of the underlying physical storage may take place, without altering or interrupting the virtual storage environment that is presented.
The storage hypervisor manages, virtualizes and controls all storage resources, allocating and providing the needed attributes (performance, availability) and services (automated provisioning, snapshots, replication), either directly or over a storage network, as required to serve the needs of each individual environment.
The term hypervisor within "storage hypervisor" is so named because it goes beyond a supervisor,[2] it is conceptually a level higher than a supervisor and therefore acts as the next higher level of management and intelligence that sits above and spans its control over device-level storage controllers, disk arrays, and virtualization middleware.
A storage hypervisor has also been defined as a higher level of storage virtualization [3] software, providing a "comprehensive set of storage control and monitoring functions operating as a transparent virtual layer across consolidated disk pools to improve their availability, speed and utilization".[4] The term has also been used in reference to use cases including its reference to its role with storage virtualization in disaster recovery [5] and, in a more limited way, defined as a volume migration capability across SANs.[6]