Increasing capacity utilisation through storage virtualisation (page 1 of 2)

In order to manage this exorbitant growth, companies often throw new disk at the problem. Subsequently senior IT managers are bombarded with requests to spend hundreds of thousands of dollars on new storage.

In the past companies have purchased far too much storage in an attempt to ensure that peak performance and availability requirements are met. This approach leaves systems greatly under-utilised. Buying new disk seems like the simple solution until they realise the costs of deploying and managing the storage. Through storage virtualisation these utilisation rates can be dramatically increased, resulting in lower total cost of ownership.

Anyone keeping track of storage technology can't help but come across storage virtualisation at nearly every turn. But what is storage virtualisation? Possessed of certain virtues or capabilities; effective in respect of inherent natural qualities or powers; capable of exerting influence by means of such qualities.

Or to put it another way any abstraction of a thing that retains the power to do what the original thing was designed to do. And that's exactly what storage virtualisation does. It abstracts storage across the enterprise and does the same job an attached storage device would do for a specific server.

Storage virtualisation is the process of taking multiple physical storage devices and combining them into logical storage devices or units that are presented to the operating system, applications, and users.

Storage virtualisation builds a layer of abstraction above the physical storage so as to not tie data to specific hardware devices, providing a flexible storage environment. It simplifies the management of storage and can potentially reduce costs through better hardware utilisation and consolidation.

An application can use, request and change available storage based solely on its required attributes, without regard for, location, physical organisation, or media type. Ideally, this should work in a completely heterogeneous environment, which includes multiple vendors and platforms for servers, software, network elements and storage devices. Storage virtualisation can ease the management of server and storage resources whatever architecture (DAS, NAS, SAN) is chosen by the customer.

Traditionally servers each had internal disk and, in cases of applications needing large data stores, direct attached arrays. In this scenario, the server can only access data in the storage device to which it is attached, and conversely, the storage is only accessible by that particular server.

Typically, some servers such as those used to run an order tracking database or e-mail experience much more traffic and capacity growth than say an HR database. However, the direct attached storage model does not allow re-provisioning of resources from under utilised systems to those about to run out of capacity. Therefore, new storage must be added to the busiest servers to avoid downtime that will occur when out-of-space conditions are encountered.

Faced with the problem of certain servers having abundant capacity while others are constantly at maximum capacity, companies turned to storage networking which allows servers to share storage resources. However, in large environments resource sharing alone is not enough. The cost to manage thousands of disks, now accessible by multiple servers, is a daunting task.

Storage virtualisation allows companies to chose the storage devices that best meet their needs, and then carve up these physical devices into logical volumes to provide resource as required.