A storage area network (SAN) is a high-speed block-based storage network that provides access to data storag . It connects servers with storage devices like disk arrays, RAID hardware, and tape libraries. In these configurations, the server’s operating system views the SAN devices as if they were directly connected. The data stored on those devices is then made available to all authorized users on the network, even if they’re in a different part of the data center or office building.
A SAN leverages 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.
The SAN acts as a dedicated network, that exists separate and apart from the common LAN A SAN enables an organization to treat storage as a single collective resource that can also be centrally replicated and protected, while additional technologies, such as data deduplication and RAID, can optimize storage capacity and vastly improve storage resilience
A SAN can support a huge number of storage devices, and storage arrays — specially designed storage subsystems — that support a SAN can scale to hold hundreds or even thousands of disks. Similarly, any server with a suitable SAN interface can access the SAN and its vast storage potential, and a SAN can support many servers.
There are a few common types of networking technologies and interfaces employed for SANs
- Fiber Channel Protocol (FCP). The most widely used SAN or block protocol, deployed in 70% to 80% of the total SAN market. FCP uses Fiber Channel transport protocols with embedded SCSI commands.
- Internet Small Computer System Interface (iSCSI). The next largest SAN or block protocol, with approximately 10% to 15% of the market. iSCSI encapsulates SCSI commands inside an Ethernet frame and then uses an IP Ethernet network for transport.
- Fiber Channel over Ethernet (FCoE). FCoE is less than 5% of the SAN market place. It is similar to iSCSI, since it encapsulates an FC frame inside an Ethernet datagram. Then like iSCSI, it uses an IP Ethernet network for transport
- Non-Volatile Memory Express over Fiber Channel (FC-NVMe). NVMe is an interface protocol for accessing flash storage via a PCI Express (PCIe) bus. Unlike traditional all-flash architectures, which are limited to a single, serial command queue, NVMe supports tens of thousands of parallel queues, each with the ability to support tens of thousands of concurrent commands.