Foreword

It is a great pleasure to write the foreword for this book. Storage networking technologies have been used for computer data storage in almost every major corporation worldwide since the late 90s. Banks, hospitals, credit card companies, airlines, and universities are just a few examples of the organizations that use these technologies. Storage networking gave birth to the concept of the Storage Area Network (SAN), a concept based fundamentally on separating storage and processing resources, with the ability to provision and manage storage as a separate service to the processing resources.

A SAN consists of not only the storage subsystems, but also of the interconnection infrastructure, the data protection subsystems, migration and virtualization technologies, and more. A SAN can have very different characteristics; for example, it can be all contained in a single rack or it might span an entire continent in order to create the most dependable disaster-tolerant configuration. In all cases, a SAN is meant to be more flexible than direct attached storage in accommodating the growth and the changes in an organization.

Several products, based on diverse technologies, are available today as building blocks to design Storage Area Networks. These technologies are quite different and each has its own distinctive properties, advantages, and disadvantages. It is important for an information technology professional to be able to evaluate them and pick the most appropriate for the various customer or organization needs. This is not an easy task, because each technology has a different history, sees the problems from its own point of view, and uses a unique terminology. The associated complex standards documentation, designed for products developers, usually produces more confusion than illumination for the casual reader.

In this book, James takes on the challenge of comparing today's most deployed storage networking architectures. To perform his analysis, he uses a powerful tool, the OSI reference model. By comparing each architecture with the OSI model, James conducts the reader through the nuances of each technology, layer by layer. An appropriate set of parameters is introduced for each layer, and used across the presented technologies to analyze and compare them. In this way, readers familiar with networking have a way to understand the world of storage controllers, while people familiar with controllers will find a different perspective on what they already know.

The first part of the book introduces the world of storage and storage networking. The basics of storage technology, including block storage protocols and file access protocols, are presented, followed by a historical evolution of how they evolved to their current status. The seven OSI layers are also introduced, giving to the reader the tools for the subsequent analysis.

The second part of the book is a deep comparative analysis of today's technologies for networked storage, including iSCSI and Fibre Channel. Each protocol suite is analyzed at the physical and data-link layers; at the network layer; at the transport layer; and finally at the session, presentation, and application layers.

The third and final part of the book relates to advanced functionalities of these technologies, such as quality of service, load-balancing functions, security, and management. In particular, security is an element of continuously increasing importance for storage networking. Because more and more digital data are vital to businesses, keeping these data secure from unauthorized access is crucial. At the same time, this growing mass of data needs to be properly managed, but managing a heterogeneous set of devices is not an easy task. Several underlying protocols for storage management have been defined or are being defined.

Storage networking is a critical concept for today's businesses, and this book provides a unique and helpful way to better understand it. Storage networking is also continuously evolving, and as such this book may be seen as an introduction to the information technology infrastructures of the future.

Claudio DeSanti

Technical Leader Data Center BU, Cisco Systems

Vice-Chairman of the ANSI INCITS T11 Technical Committee