In previous chapters, we discussed how effective storage systems are developed from the integration of multiple storage devices. Understanding the structure of these devices can help effectively utilize these technologies to support a single complex workload or a combination of disparate workloads. Underlying these concepts of storage architecture, device operation, and anatomy are the connectivity strategies that complete the data highway system. All these elements will begin to come together in this chapter as we discuss the connectivity options available to transport and deliver data from the storage system components to the computer.
Traditional system connectivity strategies have long been based upon bus architectures. A computer bus is defined as the lines and controls that connect the diverse components of a computer, ultimately making it a complete system. As we discussed in Chapter 5, this connectivity is required for the internal server components, CPU, RAM, and cache. Obviously, we know that external I/O components, such as storage devices, disks and tapes, and other peripherals like displays, keyboards, and mouse devices also require this connectivity, but in a different manner. This chapter will begin to explain the components and operation of typical bus- and network-oriented technologies, and the creative uses of various buses and network connectivity components that form the foundation for large multiple user systems.
The ability to connect storage systems through networks has greatly impacted the storage I/O industry. All of it surrounds the connectivity strategy, and the movement of storage systems from discrete bus technologies to network-oriented architectures. Understanding the bus is paramount to leveraging the movement of storage I/O into this new network model.
Another important reason to cover traditional bus technologies contrasted against the new network interconnects is that existing buses do not go away. They remain, and will remain , fundamental to getting data to and from the CPU (refer to Chapter 5 for more information). Moving data from the storage device through the storage system and on to the server within a network infrastructure still requires the effective operation of an internal bus. In order to be effective, traditional bus components must be optimized since they become parts of a new storage connectivity infrastructure. Otherwise, the most advanced and feature-rich storage network falls short at the server.