WHAT IS SAN...?
A SAN is a dedicated network that is separate from LANs and WANs whose primary purpose is the transfer of data between computer systems and storage elements.
A SAN can also be a storage system consisting of storage elements, storage devices, computer systems, and/or appliances, plus all control software, communicating over a network.
SANs create new methods of attaching storage to servers. These new methods can enable great improvements in both availability and performance. Today's SANs are used to connect shared storage arrays and tape libraries to multiple servers, and are used by clustered servers for failover.
NEED FOR SAN :
Traditional means for connecting servers and storage can no longer satisfy today's requirements for fast access to massive amounts of data. SCSI technology uses parallel cabling which severely limits speed, distance and the number of attached storage devices. Configuring SCSI (Small Computer Systems Interface) connections to support terabytes of data is impractical. In addition, traditional server/storage connections make the server the exclusive owner of its attached storage. As computing environments move from a server centric to data centric model, access to shared data resources becomes critical. Storage Area Networks are an enabling technology that allow storage resources to be shared in order to provide continuous, faster, easier access to data.
BENIFITS OF SAN :
SANs allow applications that move data to perform better, for example, by having the data sent directly from the source to the target device with minimal server intervention. SANs also enable new network architectures where multiple hosts access multiple storage devices connected to the same network. Using a SAN can potentially offer the following benefits:
Availability: A single copy of data is accessible to any and all hosts via multiple paths.
Reliability: Dependable data transportation ensures a low error rate, and an ability to recover from failures is provided.
Scalability: Servers and storage devices may be added independently of one another, and do not depend on proprietary systems.
Performance: Fibre Channel (the standard method for SAN interconnectivity) has a 8GBPS bandwidth and low overhead, and it separates storage and network I/O.
Manageability: Single image of storage media simplifies management.
