Chapter2.Establishing a Context for Understanding Storage Networks

Chapter 2. Establishing a Context for Understanding Storage Networks

Upon completing this chapter, you will be able to

• Analyze storage networking products and designs according to their connecting, storing, and wiring capabilities

• Describe the role of connecting in a storage network, and make basic distinctions between storage buses and storage networks

• Participate in discussions about storage products and implementations, locating the basic functions, roles, and locations of storage controllers, as well as identifying storage address spaces used by host systems to store data

• Describe the relationship between filing systems and operating systems and the role of space allocation performed by filing systems

• Explain the difference between block I/O and file I/O in storage networks, and describe how SAN and NAS can be analyzed as applications for storing and filing in a networked environment

People who come to storage networking with experience in Ethernet and TCP/IP networking have a tendency to start analyzing storage network architectures using the familiar protocol stack method that has been so effective in data networking. While protocol stacks obviously exist in storage networks, the stack approach does not necessarily reveal anything very useful or relevant for storage processes because so much of the interesting stuff in storage happens at the network application layer.

Much of this chapter explores a "three-legged stool" analysis for storage networking technology. This analysis breaks the subject into three distinct functional areas that divide the work of storage I/O processes and form a complete, functioning system:

• Connecting

• Storing

• Filing

The end of this chapter covers the major product groups for storage networking, storage area networking (SAN), and network attached storage (NAS). It also applies the analysis model to show how the basic functions are typically implemented in storage network solutions.