Home > Store

Storage Virtualization: Technologies for Simplifying Data Storage and Management

Register your product to gain access to bonus material or receive a coupon.

Storage Virtualization: Technologies for Simplifying Data Storage and Management


  • Sorry, this book is no longer in print.
Not for Sale



First Look: New storage virtualization technologies making storage devices easier and more cost-efficient to manage.

° Standards are just emerging in this area and so, readers are looking for a book which will guide their implementation decisions.

° All major storage vendors are embracing virtualization: EMC, Veritas, IBM, Sun, HP, Cisco.

° A vendor-neutral, technology-neutral book by a brand name storage author--about the technology in general, how it works, what it does, and what it can't do.


  • Copyright 2005
  • Edition: 1st
  • Book
  • ISBN-10: 0-321-26251-4
  • ISBN-13: 978-0-321-26251-6

Storage virtualization is a new field that has considerable interest forinformation technology managers. There is currently no single work thatprovides an objective, technical explanation of virtualization technologies.This book examines new storage virtualization technologies that automate datastorage processes, including data placement, replication, and back-up. Storagevirtualization is designed to ease storage management by presenting yourstorage network's physical assets in a logical form. Making storage networkseasier to manage can save a company money and make a storage network moreefficient. Storage Virtualization provides a technical overview of howvirtualization applications work and also includes practical case examples fromthe real world. Topics covered include: virtualizing at the host level, fabricbasedvirtualization, virtualization appliances, virtualized file systems,virtualization engines, and virtualized tape back-up.

Sample Content

Online Sample Chapter

Introduction to Storage Virtualization

Downloadable Sample Chapter

Download the Sample Chapter related to this title.

Table of Contents



1. Introduction.

    Storage Virtualization Overview.

    Core Concepts.

    Chapter Summary.

2. Files and Records.

    Application Access to Data.

    Data as Files.

      File Naming Conventions.

      File Ownership.

      Read/Write Permission Attributes.

      Time Stamping.

      File Size.

      File Data Location.

    Systematic Organization of Files.

      File System Hierarchy.

      Parsing the File System.

      Master Tables.

      File System Integrity.

      File System Strategies.

    Chapter Summary.

3. Data on Disk.

    Volume Management.

    Data as Blocks.

    The SCSI Protocol and Logical Units.

      Logical Units.

      The SCSI Architectural Model.

      SCSI Command Descriptor Blocks.

    Block Aggregation.

      RAID 0.

      RAID 1.

      RAID 0+1.

      RAID 5.

      RAID Controllers.

    Getting Data Blocks to Disk.

    Chapter Summary.

4. The Storage Interconnect.

    The Path to Storage.

    Storage Ports.

    Storage Interconnects.

      SCSI Interconnects.

      Fibre Channel SAN Interconnects.

      iSCSI Interconnects.

    The Importance of Plumbing.

    Chapter Summary.

5. Abstracting Physical Storage.

    Physical to Virtual.

      Logical Block Address Mapping.

      Virtualized Mirroring.

    Storage Metadata Integrity.

    Chapter Summary.

6. Virtualization at the Host.

    Logical Volume Management.

    Storage Metadata Servers.

    Server-based Storage APIs.

    Chapter Summary.

7. Virtualization at the Storage Target.

    Array-Based Virtualization.

    Array-Based Data Replication.

    Array-Based Point-in-Time Copy (Snapshot).

    Distributed Modular Array Virtualization.

    Chapter Summary.

8. Fabric-based Virtualization.

    Sentient SANs.

    Techniques for Switch-Based Virtualization.

    The Fabric Application Interface Standard (FAIS).

    Chapter Summary.

9. Virtualization Appliances.

    Black Box Virtualization.

    In-Band Virtualization Appliances.

    Out-of-Band Virtualization Appliances.

    High Availability for Virtualization Appliances.

    Appliances for Mass Consumption.

    Chapter Summary.

10. Virtualization Services.

    Enabling Advanced Storage Services.

    Pooling Heterogeneous Storage Assets.

    Heterogeneous Mirroring.

    Heterogeneous Data Replication.

    Point-in-Time Data Snapshots.

    Hierarchical Storage Management.

    Chapter Summary.

11. Virtualized SAN File Systems.

    Conventional File Systems.

    Distributed File Systems.

    Virtualizing File Systems.

    Chapter Summary.

12. Virtual Tape.

    Conventional Tape Backup.

    Disk-to-Disk-to-Tape (D2D2T).

    Virtualizing Tape Systems.

    Chapter Summary.

13. Storage Automation and Virtualization.

    Policy-Based Storage Management.

    Application-Aware Storage Virtualization.

    Virtualization-Aware Applications.

    Chapter Summary.

14. The Storage Utility.


    Enabling the Storage Utility.

    Chapter Summary.

Appendix A: Industry Resources.

Appendix B: Vendor Resources.

Appendix C: Observations and Speculations.





Untitled Document The following work provides an overview of storage virtualization technology and its myriad manifestations. Like any emerging technical trend, the vague outlines of virtual storage concepts have only begun to sharpen as the technology has matured to productive applications in the real world. Today, there is a diversity of storage virtualization solutions, often tailored to meet specific storage needs. This book attempts to explain the background for that diversity, how different solutions function, and the essential value that is driving storage virtualization towards higher levels of utility.

Chapter 1 (Introduction), discusses the current state of storage virtualization in the market, and provides core concepts for understanding the hierarchy of virtualization-enabled storage operations.

The following three chapters provide foundation knowledge for understanding the relationship between what the user sees and what is done behind the scenes. Chapter 2 (Files and Records) begins with data in its more familiar format, as objects manipulated by applications for persistent storage. Chapter 3 (Data on Disk) provides the link between upper layer file/record structures and lower layer block data storage. Ultimately, all data must reside somewhere, and at some point the content of a file or record will be transformed into data blocks. Chapter 4 (The Storage Interconnect) reviews the connectivity required to link servers with their storage assets, whether by direct-attached SCSI, Fibre Channel or iSCSI.

The next five chapters discuss storage virtualization proper and the various means that have been engineered to support it. Chapter 5 (Abstracting Physical Storage) examines the process of aggregating multiple storage systems into a virtual storage pool. The secret recipe behind this is the mapping of logical block addresses presented by each system to virtual block addresses that are in turn presented to servers. This may be done in various ways. Chapter 6 (Virtualization at the Host) discusses software virtualization that runs on individual servers. Chapter 7 (Virtualization at the Storage Target) discusses array-based virtualization techniques that are offered in some form by nearly all storage vendors. Chapter 8 (Fabric-based Virtualization) reviews the integration of virtualization technology with fabric switches and initiatives such as the Fabric Application Interface Standard that promise interoperable solutions. Chapter 9 (Virtualization Appliances) examines fabric-attached solutions and the innies/outties dispute between in-band and out-of-band methods. Collectively, these chapters address the "where it is done" category of the SNIA storage virtualization taxonomy.

Chapter 10 (Virtualization Services) discusses the practical application of virtual storage to real problems such as high availability and heterogeneous storage use. Storage virtualization in general is a foundation for higher level storage services such as hierarchical storage management.

Chapter 11 (Virtualized SAN File Systems) reviews another use of virtualization technology to streamline file system management and to enable distributed computing environments.

Chapter 12 (Virtualized Tape) provides an overview of the application of virtualization and system aggregation concepts to classic tape backup operations. New technologies such as RAIT (Redundant Array of Independent Tape devices) are breathing new life into an established fixture of data center environments.

Chapter 13 (Storage Automation and Virtualization) discusses the higher level services that are enabled by storage virtualization. Policy-based storage management, application-sensitive virtualization intelligence and the ability of applications themselves to leverage underlying virtualized services are new areas of development that hold great promise for simplifying storage operations.

In conclusion, Chapter 14 (The Storage Utility) examines the wide range of technical dependencies that have been setting the pace of development of storage virtualization technology. As is typical for a final chapter, Chapter 14 also provides wild speculations on the future of storage virtualization and the benefits it may yet provide as an enabling technology for a storage utility.

I have included a bibliography, which unfortunately seems to be an endangered species in technical works these days. Although there are few works on storage virtualization, there are many fine references on SAN technology that the serious reader can pursue. There is also a glossary of storage virtualization terminology as well as general SAN concepts.

The Appendix section at the end of the book includes additional reference material that hopefully will be of interest. Appendix A (Industry Resources) provides web links to industry and standards organizations. Appendix B (Vendor Resources) provides web links to storage virtualization and storage networking vendors, grouped by product type. Appendix C (Observations & Speculations) is an opportunity for industry observers, analysts, experts and customers to express their opinions on what this technology is and where it might be going.

Intended Audience
The following work should be useful for anyone who wants to understand the higher functions of storage networking. Storage managers, administrators, SAN architects, storage engineers, analysts, vendors, students and anyone involved in data storage technology should appreciate the new opportunities that storage virtualization provides. This book is therefore intended for a fairly diverse audience, from readers who already have experience with SANs to those who are just learning the benefits of shared storage solutions.

It is always difficult, however, to write a technical work with a specific reader in mind. Some readers will want more technical content; others less. Some will appreciate a broader overview, while others will want to get immediately to the point. This book attempts to provide both sufficient technical detail to be meaningful for a technical audience, and sufficient overview to provide an understanding of the subject by a less technical reader. For both types of readers, feel free to fast forward through sections that discuss concepts already well-understood, or simply of less interest.

Throughout the text I have attempted to avoid mention of specific products or vendors. This is done both to preserve objectivity in discussing technical matters as well as to extend the useful shelf life of the work despite the inevitable innovations that will be introduced. Hopefully, the concepts and relationships explained in the following chapters will provide a useful framework for understanding where we are in the space-time continuum of virtualization's maturation into more sophisticated products.


Technology is a collective enterprise, both within companies and among the companies that comprise an industry. I have had the good fortune of meeting and working with hundreds of technologists, engineers, system architects and administrators in the storage networking industry over the past eight years. In that time, networked storage has evolved into a successful mainstream technology and transformed data storage processes. Although market competition sometimes throws the storage family into dysfunction, the industry as a whole continues to spawn new solutions and new companies while attracting new talent to further technical innovation. The embodiment of the shared storage family is the Storage Networking Industry Association (SNIA), which should be credited for its contributions to standards, interoperability, education and technology advancement, and for bringing order from the chaos of vendor conflict. In the area of storage virtualization specifically, the SNIA has helped to clarify concepts and relationships within a still emerging and often confusing subject area.

Publishing is also a very collective effort. From the initial idea for a book to its appearance on a shelf, a work passes through many hands. For a technical work in particular, peer review is required to ensure technical accuracy and objectivity of content. I would like to thank Steve Blumenau, Mark Carlson, Milan Merhar and David Thiel for subjecting themselves to the review of the manuscript and for their many useful suggestions and observations. I also am indebted to Mary Franz and Catherine Nolan, my editors, and Lori Lyons, Noreen Regina and many others at Addison Wesley for overseeing this project and accommodating my sporadic output due to my heavy travel schedule.

As always, my wife Lou bears the brunt of personal sacrifice that accompanies a writing project. Although she does not share my interest in logical block address mapping algorithms, she understands that this is something I will probably outgrow at some point. In the meantime, she patiently waits for me to emerge from my study, back into multi-faceted reality to share a stroll through the garden or perhaps to help spread another ton of compose on it.

Due to my position at McDATA Corporation, I've traveled extensively over the past year, meeting customers and technologists throughout the US as well as Europe, Australia, New Zealand, India and Asia. My thanks to the many users of storage networking technology for their profound insight into the challenges of aligning technology to diverse application requirements and for affirming the global value of a technology that still has far more to offer in the future.

Tom Clark
Seattle, Washington


Download the Index file related to this title.


Submit Errata

More Information

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020