"Storage virtualization"
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
concerns.
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.

To read the PDF formatted document, click here.
To obtain permission(s) to use material from this work, please
submit a written request to SNIA, Permissions Department, 4410 ArrowsWest Drive, Colorado Springs, CO 80907-3444.
For information regarding
permissions, call (719) 694-1380.
Photography, illustration, and text incorporated into SNIA printed
publications are copyright protected by SNIA or other owners and/or
representatives. Downloading, screen capturing or copying these items in any
manner for any use other than personally viewing the original document in
its entirety is prohibited.
Notice to Government End Users: SNIA software and documentation are
provided with
restricted rights. Use, duplication or disclosure by the Government is
subject to the restrictions set forth in FAR 52.227-19 and subparagraph
(c)(1)(ii) of Rights in Technical Data and Computer Software clause at DFARS
252.227-7013.