This is excerpt was written by Greg Schulz, senior analyst, The Evaluator Group, from the book Storage Virtualization: Technologies for Simplifying Data Storage and Management, by Tom Clark and courtesy of Addison-Wesley.
Virtualizing servers, storage and networks
For anyone using computers, video games, cell phones, PDAs, or the Internet,
virtualization is all around us. The concept of Cyberspace in itself is a
form of masking the real and physical from the abstract. Yet hidden and unseen are the real and physical infrastructure items that exist to support these
virtual environments. Within this real and physical infrastructure are applications,
servers, telecommunications networks and storage, supported by
people who configure, manage and take care of them.
A key attribute of
any form of virtualization is transparency and ease of deployment. Virtualization
technologies serve to mask, abstract and transparently leverage
underlying resources without applications and consumers having to understand
or know how to use the physical attributes of the resource. For example,
virtual tape in the IBM mainframe environment, known as virtual tape
library (VTL) and virtual tape systems (VTS), utilize virtualization techniques
to adapt different technology to be used by existing tape processing
functions and software with simplicity. Another example is that some older
legacy applications still think they are processing 80-column punch cards
when in reality they are being accessed via sophisticated Java and XML-based
GUIs, which is a form of virtual I/O to adapt something old to something
new. Even more amazing is when these legacy programs have been
moved from a mainframe to a desktop or laptop computer.
Some other areas where virtualization technology and techniques are
being used are virtual disk—for example, a LUN or partition on a RAID
storage subsystem and virtual I/O devices. Volume managers and file systems
also implement virtualization techniques to aggregate (pool) and provide
a layer of abstraction between real physical and virtual resources for
transparent access of storage by applications. Other functions that are often
grouped under the umbrella of storage virtualization include mirroring and
remote data replication, long distance data access support, wide area file
services (WAFS), data movement and migration, security, and protocol
conversion.
Telephone networks are a good example of a virtual network and resource
in that you can use cell phones to talk to a traditional "land-based"
telephone, you call and talk to someone in the United States from elsewhere
in the world, and you connect your PC into a phone line for dialup access to
the Internet when high-speed access is not available. The same network can
be used for moving voice, video, and data, including faxes over wireless,
copper, and fiber optic cabling. In some instances you might need an adapter
cord, plug, or interface module; however, you can access and utilize the A virtual storage network similar to a telephone network supports many
different interfaces—for example, Fibre Channel, Ethernet, InfiniBand, SATA, SAS, SONET/SDH, and others, as well as multiple storage networking protocols including
SCSI, FCP, iSCSI, FCIP, iFCP, TCP/IP, iSER and others. A virtual storage
network can also support access via block, file (NAS), and object-based to
meet the different needs of applications and adapt to support different technology
resources. Like the telephone network, you may need special plugs,
adapters, or connectors to access and use a storage network. Standard interfaces
and protocols are needed and continue to evolve to leverage storage
virtualization, including SMI-S and FAIS as well as others being worked on
by IETF, ANSI T11, SNIA, DMTF and DAT collaborative, among others.
Not so long ago, a major discussion point was the convergence of block
and file, also known as SAN and NAS. We are now seeing the convergence
of servers and storage, which is only appropriate given discussion of virtual
servers and virtual storage. While storage virtualization services continue
to be deployed on servers and storage subsystems, they are also being deployed
in the network on appliances, switches and gateways.
A barrier to fully leveraging virtual servers, virtual storage, and virtual
networks may not be technology, but rather political and budget boundaries,
as well as "turf" wars within organizations. Even with organizations
continuing to run and be organized as they are, there are benefits from improved
resource usage and improved management that can be realized by
server, storage and network virtualization, as we have seen over past several
years.
So the next time you access a web page, perform a Google search, hit
the return key on a website, or perform some other function using your
computer, pause for a moment to think about what makes up cyberspace.
While it may seem like a virtual environment, keep in mind that there is a
real infrastructure of servers, storage, and networks that have been virtualized
to enable you not to have to worry about the technologies that exist to
enable you to do what you need to do.
This is excerpt was written by Greg Schulz, senior analyst, The Evaluator Group, from the book Storage Virtualization: Technologies for Simplifying Data Storage and Management, by Tom Clark and courtesy of Addison-Wesley. If you found this book excerpt helpful, purchase the book from Addison-Wesley.
