4.5 Network Control Points

The storage network, or fabric, acts as the primary intermediary between traditional host and target storage services implementations . Coupled with the introduction of intelligent devices, the network itself becomes a control point of the overall storage infrastructure. In the past, many have referred to the network as nonintelligent plumbing that was largely irrelevant. This may have been true when intelligence resided on either the host or the target. However, with the network now providing increasing levels of storage services, it can no longer be ignored.

Improvements in network technology, such as the introduction of Gigabit Ethernet, coupled with the ability to put block-based storage on IP networks, dramatically shift the network landscape and have serious ramifications on storage control points. In the past, network interconnects were separated by overall bandwidth, distance capabilities, and scalability as measured by the number of nodes on the network. Figure 4-15A shows how the interconnects split across interprocessor communication, I/O, LANs, and WANs. Distance is on the X-axis, node scalability on the Y-axis, and bandwidth represented by circle size.

Figure 4-15. Leveling the interconnect playing field.

The introduction of Gigabit Ethernet and technologies such as iSCSI enables Ethernet to accomplish the same kind of functions previously limited to SCSI and Fibre Channel, as shown in Figure 4-15B. The importance of this shift cannot be underestimated. For the first time, an interconnect technology not dominated by the storage community is encroaching on traditional storage territory. It is likely that the storage community, once isolated by the self-directed nature of its interfaces, has yet to fully grasp the consequences of this network convergence. Given Ethernet's ability to grow, scale, and adapt to a wide variety of environments, its capabilities are likely to cover all of the I/O space in time, as shown in Figure 4-15C. This doesn't mean that traditional I/O technologies will disappear, but rather that the playing field in terms of features and performance will be leveled to the point where the average customer would not know the difference.

The networking community, however, has rapidly embraced the evolutionary nature of Ethernet and is already adapting to Ethernet's ability to move to the MAN and WAN space, especially with the introduction of 10-Gigabit Ethernet, as shown in Figure 4-15D.

Vendors and customers likely to prosper in storage will recognize the adaptive path of networking technologies and embrace the change. Others will futilely resist and grapple to sustain alternative storage-focused interfaces, continuing to invest in their propagation by developing incremental, yet ultimately insufficient, technology improvements.