Storage area network or SAN is a networking architecture that enables the connection of remote storage devices to servers so that operating systems can access these devices. A SAN is usually found in enterprise environments where it connects islands of data storage with the help of a high-speed network. SANs allow applications to store their data on virtual hard drives; the applications treat them as local file systems that are not shared between them. This does not allow for cache synchronization, helps in data security and prevents corruption of files. Although data can be viewed concurrently, editing and rewriting is prevented and therefore unintentional corruption that would otherwise be unavoidable is prevented. This is a big advantage of a SAN over conventional file-sharing systems.
SANs help to increase and better utilize storage capacity as they connect multiple servers to several storage units. SANs are used to make available frequently used data that is connected to hard drives such as email servers, user information, and file servers that manage frequently used transactional data.
Since SANs do not carry any application traffic, they are a network between servers and storage devices; they do not create bottlenecks in the LAN. This allows free and fast passage to all data, especially mission-critical data. Since SANs are able to provide storage-to-storage connectivity as well, they are ideal for use with new clustering technologies where computers are deployed in clusters to improve performance. It also enables them to be used with NAS devices so that disk and tape capabilities can be extended to multiple servers.
SANs are developed using fiber channels that enable speeds of up to 200 Mbps. Fiber channel supports multiple servers and can connect them to various devices. A fiber channel San network is made up of fiber channel switches. Fiber channel routing offers major scalability benefits as it enables the transfer of data between various fiber channel fabrics without merging the fabrics. A fiber optic bus can provide connectivity up to 10 kilometers before one has to make use of an extender. Network and channel protocols supported by SAN include SCSI, HIPPI, IP, ATM, etc.
SANs allow remote booting of the servers which leads to quick and easy replacement of servers not working properly. Disaster recovery is made easy through SANs as storage replication can be implemented by disk array controllers and server software both. SAN over IP WAN allows for business continuity in the event of a disaster. One of the early issues with SANs utilizing fiber channel technology was the lack of interoperability between switches and hardware manufactured by different vendors. This, however, has been rectified to a great deal because now standards are in place.
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Author: Nand Kishor
Article Source: EzineArticles.com
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