Magnetic disks form the foundation of online storage systems. These devices are augmented in storage architectures with magnetic tape, enabling an economical and enduring media for storing historical information. Additional storage technologies such as solid-state disks and optical devices play both specialized and enabling roles that support these two fundamental storage devices. Although the concepts in this chapter may seem elementary in nature, the mastery of these storage principles are an integral part of understanding how to apply these basic storage components optimally when designing and implementing a storage network.
Storage architectures must support various, and at times, disparate business applications. These applications demonstrate various I/O requirements that place a demand on the storage devices. The specific I/O requirements for the application are referred to as an I/O workload (more information about I/O workloads can be found in Chapter 17). The understanding of storage at the device level will contribute to developing an entire storage system that forms the critical basis for all application performance.
Application systems designed with the supporting storage devices in context with workloads begin to develop into responsive infrastructures . Without device knowledge and consideration, storage systems often form monolithic storage farms that dictate a one size fits all approach. Such conditions set the stage for unresponsive and costly application performance. With today's Plug and Play implementation frenzy, the thought and analysis given aligning compatible storage devices with storage workloads is generally an afterthought (more information regarding workload planning for storage networks are contained in Part V and Chapters 21 and 22).