Storage Virtualisation

What is storage virtualisation?

The best definition of virtualisation is probably data abstraction. The technology involves taking multiple physical storage devices and combining them into logical storage devices or units that are presented to the operating system, applications and users. It builds a layer of abstraction above the physical storage so that data isn’t tied to specific hardware devices, providing a flexible storage environment.

Why do organisations need this technology?

For organisations having islands of data scattered across different departments, storage virtualisation gives them the ability to view and manage multiple, networked heterogeneous storage devices as if they were a single pool of storage managed from a single console. To an operating system, the virtual storage appears as one device, regardless of the types of storage devices pooled. This also means that end enterprise-users find attaching or detaching extra storage to be easier.

Can it reduce TCO?

Virtualisation of data resources separates dependency between applications, the operating environment and the hardware. Even in a mixed environment, these resources can be allocated and reallocated on demand. Because resources are treated as a single system, the problem of managing individual components is no longer a problem. Storage virtualisation also helps reduce TCO (Total cost of ownership). Though the cost of computing power and storage has been coming down steadily, data management is a complex issue. Storage virtualisation can potentially reduce costs through better hardware utilisation and consolidation. An application can use replace and change available storage based solely on its required attributes, without regard for location, physical organisation or media type.

Virtualised storage is not restricted by the capacity, speed or reliability limitations of the physical device that comprise them. Additionally with storage virtualisation, platform independent, software-based solutions eliminate the cost and price premiums of exclusive solutions. It brings the entire storage infrastructure to the highest level at the lowest cost because the solutions work on a variety of platforms, with a wide range of storage hardware.

How does one go about selecting the right tool?

While there are many products in the market today that are delivering virtualisation capabilities, an organisation should select only those products that provide an analysis of return on investment (RoI) and total cost of ownership (TCO). Today each application in a data centre has its own server, storage, and networking resources assigned to it. Because services and applications aren’t designed to share, each device has to carry its own excess capacity in order to meet peaks in demand. By opening up previously static relationships between hardware, applications, and the operating environment, HP, IBM, Sun, CA, EMC, Veritas, Brocade, Legato all have solutions in this area. Virtualisation unifies the myriad storage systems of an enterprise into a common resource, which can be provisioned, managed and supported in a consistent, coherent way.

For more information about storage virtualisation visit www.snia.org/education/tutorials/spr2004/virtualization/