October 30, 2007, 11:42 AM — IT managers have been advised to be wary of vendor hype surrounding storage
virtualization as it is a technology that is poorly defined, misunderstood and
not widely used, according to Dr. Kevin McIsaac, an advisor at research firm
Intelligent Business Research Services Pty Ltd. (IBRS).
Despite all the hype, McIsaac said over the next two years network based storage
virtualization will remain a niche, while thin provisioning will enjoy rapid
adoption in the enterprise.
And while McIsaac readily admits server virtualization is one of the best IT
infrastructure trends to emerge in many years, he said the situation is very
different when it comes to storage virtualization.
"This idea of being able to layer virtualization over existing storage
arrays is seriously flawed," he warned.
McIsaac said a reasonable definition of storage virtualization is "the
abstraction of logical storage from physical storage". However, given the
sweeping nature of this definition it is not surprising that the technology
"The first step in understanding storage virtualization is to recognize
that many of today's commonly used techniques and technologies are examples
of virtualization including a file system or a storage array," McIsaac
Rather than thinking of it as a specific new product or feature, McIsaac said
it should be thought of as a broad technique that can be deployed at any layer
of the storage hardware and software stack to simplify the storage environment.
"Network based virtualization, which involves using a device in the network
to provide an abstraction layer over storage arrays, is usually what vendors
mean when they refer to storage virtualization," he explained.
"The idea is to layer virtualization over existing arrays to create a
single storage pool, simplify management and eliminate vendor lock-in. But this
idea has significant flaws."
Organizations typically moved to an external storage array, either via a SAN
(storage area network) or a NAS (network-attached storage), to achieve higher
utilization by sharing the same pool of spare disk across multiple servers.
McIsaac said applying network based storage virtualization to pool arrays isn't
likely to improve this environment if efficient utilization hasn't already been
"Network-based storage virtualization results in a lowest common denominator
view of the infrastructure, eliminating the value added features of the array;
this investment in the advanced features of the storage array could be lost
making it a waste of money," he said.