Chapter1.Data Access in the Internet Era

Chapter 1. Data Access in the Internet Era

Upon completing this chapter, you will be able to

• Participate in discussions and analysis of data access architectures and requirements

• Describe the availability shortcomings of legacy storage architectures

• Analyze DAS storage for scalability and utilization problems

• Participate in planning sessions for justifying storage network solutions to replace DAS storage

Storage networking promises to be one of the most dynamic areas in all of information technology for several years to come. If the evolution of other groundbreaking networking technologies provides any clues, we should expect network storage to radically improve the ways organizations leverage data. As an infrastructure element, network storage is being used to make applications and systems more scalable and robust.

The initial concept behind network storage is simple: extend legacy storage processes into a network-connected world. Eventually, these legacy storage processes will be replaced as new methods are developed, but to date the major benefits have been the result of applying network flexibility to storage applications.

One of the first challenges in implementing network storage is gaining a clear understanding of the intricacies and idiosyncrasies of storage. Many implementation details defy intuition and logic. Storage networking can be incredibly powerful, but its strength can't be fully realized without knowing storage in sufficient detail.

Many newcomers to network storage approach the topic having ample experience with networking technologies. There is no question that a strong networking background is helpful, but one should always be careful of extending Ethernet and TCP/IP data networking assumptions to storage networking. For instance, there are very different expectations for transmission quality in TCP/IP networks and in storage networks. Storage communications have always assumed reliable, in-order delivery with very few retries. Legacy TCP/IP networks, on the other hand, have been built with the assumption that most networks have imperfections and that packets will be lost or delivered out of order. Because it represents the integration of these different legacy communications systems, storage networking must find ways to bridge these different perspectives.

Information Technology (IT) professionals who find themselves in the role of planning for, architecting, implementing, and managing storage networks need to understand both parts of the storage networking equation, as the wrong assumptions can be very costly.