Virtualization technology: Server, storage and network virtualization

Virtualization technologies mask, abstract and transparently leverage underlying resources in server, data storage and networking environments.

Storage Virtualization: Technologies for Simplifying Data Storage and Management

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.


  • Introduction: Observations on storage virtualization
  • Delivering a global storage solution
  • Virtualizing servers, storage and networks
  • Moving storage virtualization up the stack
  • Virtualization of data
  • Benefiting from virtualization
  • Future directions for virtualization: A foundation for the future

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.

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