What Is a Storage Area Network or SAN? – SAN vs. NAS | NetApp

Storage area networks (SANs) are the most common storage networking architecture used by enterprises for business-critical applications that need to deliver high throughput and low latency. A rapidly growing portion of SAN deployments leverages all-flash storage to gain its high performance, consistent low latency, and lower total cost when compared to spinning disk. By storing data in centralized shared storage, SANs enable organizations to apply consistent methodologies and tools for security, data protection, and disaster recovery.

A SAN is block-based storage, leveraging a high-speed architecture that connects servers to their logical disk units (LUNs). A LUN is a range of blocks provisioned from a pool of shared storage and presented to the server as a logical disk. The server partitions and formats those blocks—typically with a file system—so that it can store data on the LUN just as it would on local disk storage.

SANs make up about two-thirds of the total networked storage market. They are designed to remove single points of failure, making SANs highly available and resilient. A well-designed SAN can easily withstand multiple component or device failures.