Storage is a facility that computer users want to access at any time, from any location, with a minimum amount of management.
Users expect the storage devices to provide enough capacity and to be reliable. The amount of storage that users require, however, is increasing quickly. Internet users use large amounts of storage daily. Many users are mobile, access patterns cannot be predicted, and the content of the data becomes more and more interactive. Because the amount of data that is processed is large, it can no longer be managed manually. Automatic management is required, as are new levels of bandwidth and load balancing. Also, it is important that all this data can be shared between different types of operating systems, because the communication networks cannot process the large replication, download, and copying operations that would otherwise be required.
Storage area networks (SANs) are high-speed switched networks that let multiple computers share access to many storage devices. SANs allow for the use of advanced software that automatically manages the storage of data. With such advanced software, the computers that are connected to a particular network can, therefore, access storage wherever that storage is available in the network. The user is no longer aware of, and no longer needs to know, which physical devices contain which data. The storage has become virtualized. In a similar way to how virtual memory has solved the problems of the management of a limited resource in application programs, the virtualization of storage has provided a more intuitive use of storage, while software quietly manages the storage network in the background.