Chapter7.Device Interconnect Technologies for Storage Networks

Chapter 7. Device Interconnect Technologies for Storage Networks

Upon completing this chapter, you will be able to

• Participate in discussions with colleagues about the relative strengths of and differences between the various storage interconnect technologies used in storage networking

• Characterize the applications best suited for different types of storage interconnects

• Make recommendations for areas to test when evaluating disk subsystems with different types of storage interconnects

• Explain the difference between ATA and SATA technologies

Most people think of storage networks primarily as being storage connectivity over a network. However, when you look under the covers of network storage subsystems, you find out that they also depend on short-distance storage interconnect technologies that connect storage devices to controllers. In other words, storage area network (SAN) and network attached storage (NAS) networks can be thought of as the external network connections while interconnects are the internal storage connections. Figure 7-1 illustrates.

Figure 7-1. External Storage Networks and Internal Storage Interconnects

Several different storage interconnect technologies are used with SANs and NAS, including parallel Small Computer Systems Interface (SCSI), AT Attachment (ATA), Fibre Channel, and Serial ATA (SATA). In addition to these, it now appears likely that another interconnect, Serial Attached SCSI (SAS), will be added to the list in the next couple of years.

This chapter looks at the major interconnects used in storage networks and highlights their differences so readers can analyze how to most effectively use them.

NOTE

USB and FireWire are interesting interconnect technologies, but they have not really had any impact on storage network products yet. FireWire especially has interesting networking capabilities, but like USB it is being implemented in products with external connections to desktop systems, not servers. As the lines between technology classes blur over time, it is still necessary to make meaningful distinctions between a high-end storage subsystem and a DVD drive. So, USB and FireWire fans, I'm sorry, but your technology didn't make the cut for this book.