Chapter 5. Designing the SAN

In this chapter, you get a look at designing and creating a workable storage area network (SAN), according to tried-and-true basic principles of SAN design. After reading this chapter, you should be able to quickly pick out the best design for your needs. As you'll see, there are a lot of different ways to design a SAN. We start with a basic design that fits most requirements. We also show you how to scale up your SAN design, which will enable you to add more servers and storage as your needs require.

Basic SAN Designs: Understanding the Layers

As shown in Figure 5-1, SANs are built in three layers:

  • The host layer: This is where all your servers reside. The servers run the high-performance applications that run your business, and those application servers need hard-drive storage space to store their data. Every server in the host layer uses a Host Bus Adapter (HBA) to connect it to the fabric layer. The HBA connects the server with a fiber-optic cable to the hubs or switches in the fabric layer.

  • The fabric layer: This is the actual network part of the SAN. It's also known as the SAN layer because it's the basic plumbing of the storage area network. It's the central connection point between the servers in the host layer and the storage devices in the storage layer. The devices in the fabric layer house most of the intelligence that enables SAN communications to occur so your data can flow between the host layer and the storage layer.

  • The storage layer: This ...

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