has become the buzzword in the storage industry, especially with the
increased acceptance of storage networks. But besides all the hype, there is
considerable confusion, too.
Many users have been disconcerted by the terminology, the different ways in
which vendors present virtualization, and the various technical
implementations of storage virtualization. In addition, the two alternative
approaches to virtualization based on in-band and out-of-band technologies
have resulted in much discussion about the pros and cons of the two
technologies. Needless to say, in many cases thee discussions have generated
more "heat than light" and have done little to clarify the issues for end
users needing to address their day-to-day storage management challenges and
Acting in its role as an educator, SNIA has undertaken to offer clearer
definitions and terminology in general, and to convey them to both vendors
and users. In order to provide a common frame of reference for discussions
about storage terminology, SNIA has developed the Shared Storage Model
(SSM), which allows us to place different storage technologies within a
consistent framework and helps users to understand where a particular
technology is implemented and how it relates to other storage technologies (to learn more about SSM, please
visit the tutorial located here). Accordingly, we've chosen to use
SSM as an overall framework for explaining virtualization in this booklet.
The model offers a general structure for describing various architectures
for accessing storage systems, and can be considered an architecture
vocabulary. It shows differences between approaches without evaluating them
per se. As a result, it lets vendors present their
solutions--including any architectural differences--more clearly, and gives
users a better understanding of what the vendors offer.
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