A storage area network (SAN) is an open system storage architecture that allows multiple host computers to share multiple storage peripherals to share storage peripherals via a fibre channel (FC) network switch. Fibre channel is a serial data transfer architecture standardized by the American National Standards Institute (ANSI). Fibre channel combines high bandwidth and high scalability with multiple protocol support over a single physical connection. This enables the SAN to serve as both a server interconnect and as a direct interface to storage devices and storage arrays. Fibre channel supports its own as well as other higher level protocols including the SCSI protocol. Due to the popularity of the SCSI protocol, it is currently common practice to use fiber channel technology to convey established SCSI commands via the fiber channel protocol for SCSI standard. In fibre channel topologies, SCSI storage devices, such as hard disk storage devices and tape devices, can be used to store data that can be retrieved by a software application. Serial strage architecture (SSA) and enterprise system connection (ESCON) channels are also supported. Fiber channel fabrics allow for millions of devices to be connected to one or more computer systems. Fibre channel topology can be selected depending on system performance requirements or packaging options. Possible fibre channel topologies include point-to-point, crosspoint switched or arbitrated loop. Fibre channel switches can connect host servers with storage devices creating a high speed switching fabric. Requests to access data pass over this switching fabric and onto the correct storage devices through logic built into fibre channel switches. Host servers connected to the switching fabric can quickly and efficiently share blocks of data stored on the various storage devices connected to the switching fabric. A SAN typically utilizes a block-oriented protocol for providing storage to compute nodes, while general purpose networks (GPNs), including local area networks (LANs), wide area networks (WANs) and the Internet, typically implement file-oriented protocols. Using fibre channel connections, storage area networks can provide high-speed compute node to/from storage node, and storage node to storage node, communications at distances that allow remote workstation and server compute nodes to easily access large shared data storage pools. With SAN technology, management of storage systems can be more easily centralized than with alternative technologies, and data backup is facilitated. Both factors act to increase overall system efficiency. The large distances allowed by fibre channel SAN technology make it easier to deploy remote disaster recovery sites than with prior technology. Mass data storage systems are implemented in networks or fabrics that provide means for communicating data between systems that use data, and the storage systems that implement the physical storage. System area networks provide significant benefits as compared to other network configurations. A major advantage of the SAN configuration is that communication via the SAN is specific to data storage operations. The resultant independence of storage related traffic in the SAN provides a more efficient means of carrying out required storage operations. Unlike traditional networks that utilize point-to-point communication paths and have distributed file systems, SANs may allow all computing devices access to each of the storage devices. Connectivity is shared among the computing devices and the storage devices within a SAN environment. SANs are highly localized having multiple server or host computer systems communicating with each other and sharing one or more storage subsystems and possibly tape, optical or other backup media changers. Many SANs have multiple host computer systems that may be used to perform several different but complimentary functions. A plurality of SANs may be interconnected with bridges, such as a WDM device, and located at different geographic locations to form wide SANs. The storage area network (SAN) has become a necessity for virtually every sector of commerce where there is a requirement for storing data with high capacity, high speed, and increased reliability.

A storage area network typically includes a plurality of host devices connected through a switched fabric to a plurality of storage arrays. The host devices access a plurality of logical data volumes present on the plurality of storage arrays, usually on behalf of a plurality of client devices. Each storage array is connected to one or more host devices through the switched fabric. A SAN is intended to increase the pool of storage available to each server in the computer network, while reducing the data supply demand on servers. In large enterprises, a storage area network connects multiple servers to a centralized pool of disk storage. Compared to managing hundreds of servers, each with their own disks, a SAN improves system administration. By treating all the storage as a single resource, disk maintenance and routine backups are easier to schedule and control. Storage area networks are presently being integrated into distributed network environments. Storage area networks also differ from general purpose networks in that SANs carry large amounts of data with low latency, and historically have lacked a mechanism for implementing security across the network. Storage area networks are characterized as high-speed networks primarily conveying data between storage nodes and compute nodes, often utilizing separate network hardware from that used for general-purpose network functions. Storage nodes are machines that primarily serve storage to other nodes of the network, while compute nodes are typically computers that use storage provided by storage nodes. Compute nodes on storage area networks are often also server nodes of a GPN. In these networked systems, the SAN is often implemented with separate, high-speed, network hardware from that of the GPN so as to offload the data from the GPN, thereby increasing GPN and effective CPU performance. Storage area networks may be operated in a "clustering" environment, where multiple compute nodes have access to at least some common data, the common data may in turn be stored with redundancy. SANs having multiple processors accessing a common database stored with redundancy, are often used for transaction processing systems. SAN systems enable the possibility of storing multiple copies or replicas of data at various physical locations throughout the system. Data replication across multiple sites is desirable for a variety of reasons. When one copy becomes unavailable due to equipment failure, a local network outage or the like, a replica located at an alternate site can allow access to the data. Replicated data can also theoretically improve access in normal operation in that replicas can be accessed in parallel, avoiding bottlenecks associated with accessing a single copy of data from multiple systems. Storage area networks offer centralized storage of data for increased efficiency and data handling. A properly implemented storage area network provides data access reliability and availability, unobtrusive capacity expansion such as with the addition of data storage devices, improved data backup and recovery, and performance that is competitive with local data storage.