A Deja vu View of Virtualisaton

By | August 13, 2006

Companies recognise the need for new storage initiatives, such as simplifying the infrastructure, improving resilience and managing information over its lifecycle. But in spite of all the industry hype, storage virtualisation is NOT the definitive answer to all of these data storage problems.

IT managers are looking for a way to cut through the disparate legacy silos of information so that they can manage all of their data as a single logical, structured entity, wherever it is located, and ensure the accessibility, availability, security, integrity, resilience, and compliance of that data.

This problem is bigger than virtualisation. Virtualisation is just one of a number of industry technology trends, including Information Lifecycle Management (ILM) and Intelligent Storage Networking, which need to come together in order to address the real problems companies have with managing the growth, accessibility and regulatory compliance of such huge volumes of data.

Whilst the name might be new, the broad concept of virtualisation is not. Twenty years ago, when the mainframe dominated the date centre, before open systems was a major part of the IT Managers’ life, storage vendors used a technique called device emulation to ‘hide’ the physical characteristics of the storage devices so that they could all present the same ‘logical’ view and be utilised in any mainframe environment.

The complexities of providing a single logical view of the storage in today’s open systems environments are arguably greater than those of the mainframe days. Even so, there are parallels to be drawn and the need for device emulation was, in essence, similar to today’s need for virtualisation.

While device emulation meant that data could be placed on any storage device attached to the mainframe without concern for which vendor provided the hardware, it did not address the increasing complexity of trying to manage the placement of huge volumes of mainframe data. That became the job of HSM software, which would undertake automatic backup, recovery, migration, and space management functions according to pre-defined storage policies.

Around the same time, there was also another important development. Storage devices had been directly attached to mainframes and it was impossible to share storage between applications running on different servers. However, the development of the ESCON Director – a forerunner to today’s SAN Director – provided the ability for applications running across multiple mainframes and partitions to access all of the storage devices in just the same way as today’s SANs.

With this any-to-any access to a single storage view, HSM became so vital to the management of the mainframe that soon, together with complementary software, which provided data movement, copy, backup, and additional media, device and space management functions, it became integral to the mainframe operating system, as System Managed Storage (SMS).

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