Home > Articles > Networking > Storage

  • Print
  • + Share This
This chapter is from the book

1.3 Text Overview

The first edition of this work attempted to provide a comprehensive overview of SAN technology for both technical and nontechnical readers. Because SANs were relatively new arrivals on the storage scene, it was possible to accomplish this goal in a fairly short work by using a dense writing style that one reader has called "information compression." The current work necessarily includes additional discussion of new SAN technologies that have emerged over the past three years, but it attempts to preserve an information compression ratio that delivers more knowledge in fewer pages. Because few people in today's information technology space have the time to read a work cover to cover, it is hoped that this edition of Designing SANs will be a useful reference for readers who need ready access to specific information on various SAN topics.

The chapter progression begins with lower-level technical overviews of storage and networking primarily related to the underlying SAN plumbing that supports higher-level applications. This discussion includes both abstract standards and the products developed from them. SAN infrastructure components that were previously based on Fibre Channel alone now include IP-based solutions, so additional space in the current work is devoted to heterogeneous SAN design options. Following the infrastructure discussion, middle-layer SAN issues, such as storage-specific applications, management, and virtualization, are reviewed. With these additional concepts in place, it is then possible to discuss concrete implementations of SANs in customer environments. The text concludes with a general overview of outstanding issues yet to be resolved in the areas of standardization, interoperability, and management, along with speculation on the future direction of storage area networking as the adoption of SANs expands throughout the market.

Chapter 2 provides an overview of both storage and networking concepts and explains how the fusion of these technologies has created new means to solve data storage issues. As in any dialectical synthesis, the resulting product has new attributes quite distinct from its constituent parts. Storage has thus placed new demands on networking, and networking has fundamentally altered storage relationships. As a fusion technology, storage networking requires a basic understanding of networking and storage—a need addressed by this chapter—as well as new concepts addressed by later chapters.

Storage area networking has deep roots in Fibre Channel technology. Fibre Channel was the first serial transport to successfully solve gigabit transport, data encoding, optics, transport protocol, and topology issues required for high-performance shared storage applications. Chapter 3, Fibre Channel Internals, reviews the lower-level operation of the Fibre Channel physical and protocol layers, including framing, class of service, flow control, and naming and addressing conventions.

Chapter 4 provides the foundation for understanding Fibre Channel topologies that have been employed for SANs. Today, most Fibre Channel SANs are based on switched fabrics. Chapter 4 therefore focuses on fabrics and fabric switch features and devotes less space to point-to-point and arbitrated loop configurations. Arbitrated loop, however, is still commonly used for JBODs ("just a bunch of disks") and as back-end storage for some NAS products, and so this chapter also discusses loop principles.

Chapter 5 examines the Fibre Channel products that have been created to accommodate server and storage attachment to a SAN. This spectrum of products includes transceivers and cabling, host bus adapters (HBAs), Fibre Channel-attached storage and tape, loop hubs, and fabric switches. Because extension of native Fibre Channel over wide areas using tunneling or dark fiber is dependent on the same Fibre Channel behavior demonstrated in a local environment, native Fibre Channel extension and IP tunneling products are also grouped into this chapter.

Over the past two years, storage over IP has entered the SAN market to complement or sometimes compete with Fibre Channel solutions. Chapter 6 provides a brief overview of IP SAN technology. Native IP storage protocols include Internet Fibre Channel Protocol (iFCP) and Internet SCSI (iSCSI). As with Fibre Channel, IP storage must provide discovery and naming mechanisms, and these are reviewed in the sections on Service Locator Protocol (SLP) and Internet Storage Name Service (iSNS). Because IP SANs directly converge mainstream IP networking with storage, additional IP services, such as Quality of Service (QoS) and IP Security that can be applied to storage, are discussed. IP is also an enabling technology for metro and wide area SANs, and Chapter 6 concludes with a review of buffering and speed-of-light latency issues that a storage architect must consider when designing SANs over distance.

Chapter 7 examines various classes of IP SAN products that have been or will be introduced into the market. Much of an IP SAN infrastructure can be borrowed from mainstream IP networking. Gigabit Ethernet switches and IP routers, for example, are not specific to SANs but can be incorporated into SAN design without modification. Similarly, TCP offload engines (TOEs) have been developed to solve host processing issues historically associated with TCP but also have become enablers for high-performance IP SANs. IP storage gateways can perform Fibre Channel-to-iSCSI or Fibre Channel-to-iFCP conversion, or both. As in the discussion of Fibre Channel products, the focus here is on product functionality and not specific vendor implementation. Although it is tempting to review and compare individual vendor products, the market is moving too quickly for a book to capture capabilities of specific vendor products.

After establishing a foundation for understanding SAN plumbing options in the preceding chapters, Chapter 8 begins a higher-level discussion of SAN software applications. This chapter reviews storage-specific applications, including server clustering, backup, data replication, distributed file systems, and file sharing. Some of these solutions are software only; others can be embedded in storage hardware products.

Chapter 9 examines problem isolation in SANs. Problems can and do occur eventually and can occur at any layer in a SAN configuration. This chapter looks at some simple problem isolation techniques as well as hardware and software tools that facilitate identifying and isolating faults in a SAN.

Management of SANs is a broad topic because it includes management of the SAN transport as well as data placement and resource management. Chapter 10 discusses the major categories of SAN management and management protocols that can be used. This chapter also includes an overview of the Common Information Model (CIM) initiative. Although CIM has been under construction for some time, it has recently received strong industry support in the hopes that it will enable a coherent and unified solution for managing both data transport and data placement from a single platform.

Chapter 11 takes the reader into the Twilight Zone technology of storage virtualization. Like a quantum particle in a transient state, storage virtualization can both exist and not exist in the same moment. Elementary storage virtualization such as RAID certainly exists and has provided significant value for storage applications for some time. Advanced, application-aware storage virtualization has yet to appear and will require significant engineering effort to bring into being. The vendor and marketing hype aside, storage virtualization holds great promise for SANs and will enable customers to implement shared storage solutions throughout their networks.

Chapter 12 covers application studies of SAN solutions. From storage-intensive operations, such as full-motion video editing and prepress graphic creation, to more ubiquitous customer requirements for streamlined tape backup, SANs have successfully addressed a wide range of business needs. In discussing storage consolidation, server clustering, content distribution, disaster recovery, and other applications, the material in Chapter 12 attempts to offer examples that accommodate Fibre Channel, storage over IP, or both in a heterogeneous solution. Where possible, the SAN infrastructure is presented in a technology-neutral way so that the SAN architect can thereafter overlay the customer transport of choice.

Chapter 13 reviews some of the main areas of concern for SANs, including standardization, interoperability, and management. These are mutually dependent and overlapping issues that vendors and customers together must address. Standardization of a technology, for example, has little value for customers if it does not result in interoperability of vendor products. Similarly, even the most sophisticated management platform would be ineffectual if its cycles were consumed reporting errors due to standards violations or interoperability conflicts.

Chapter 14 is my opportunity to engage in wild speculation about the future of SAN technology. No one has a crystal ball in such a fast-paced technology, and the storage industry itself is being shaped by the push of emerging technologies and the pull of customer demands. Although InfiniBand may help transform the high-performance server market, storage virtualization and IP storage networking are now the main forces driving SANs to ubiquitous adoption.

This edition of Designing SANs also includes supplementary material in the appendixes to provide background and reference information on storage networking. In addition to resource and vendor listings, material is provided on the standardization process behind SAN development, including the work of NCITS/ANSI T10 and T11 groups and the Internet Engineering Task Force (IETF). The structure and activity of the SNIA are also included, as is the work of the SNIA Technical Council on the Shared Storage Model and the SNIA Education Committee's SNIA Dictionary. Some of my previously published articles on storage networking are grouped in Appendix G, SAN Essays.

  • + Share This
  • 🔖 Save To Your Account

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.

Overview


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.

Surveys

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.

Newsletters

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.

Security


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

Children


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

Marketing


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.

Choice/Opt-out


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.

Links


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