A storage area network ( #SAN) is a dedicated, high-speed network that provides access to block-level storage. SANs were adopted to improve application availability and performance by segregating storage traffic from the rest of the LAN. SANs enable enterprises to more easily allocate and manage storage resources, achieving better efficiency. “Instead of having isolated storage capacities across different servers, you can share a pool of capacity across a bunch of different workloads and carve it up as you need. It’s easier to protect, it’s easier to manage,” says Scott Sinclair, senior analyst with Enterprise Strategy Group.
What is in a SAN?
A SAN consists of interconnected hosts, switches and storage devices. The components can be connected using a variety of protocols. Fibre Channel is the original transport protocol of choice. Another option is Fibre Channel over Ethernet (FCoE), which lets organizations move Fibre Channel traffic across existing high-speed Ethernet, converging storage and IP protocols onto a single infrastructure. Other options include Internet Small Computing System Interface (iSCSI), commonly used in small and midsize organizations, and InfiniBand, commonly used in high-performance computing environments.
Vendors offer entry-level and midrange SAN switches for rack settings, as well as high-end enterprise SAN directors for environments that require greater capacity and performance. Example vendors that offer enterprise SAN products include Dell EMC, Hewlett-Packard Enterprise, IBM and Pure Storage.
How is NAS different than a SAN?
SAN and network-attached storage (NAS) are both network-based storage solutions. A SAN typically uses Fibre Channel connectivity, while NAS typically ties into to the network through a standard Ethernet connection. A SAN stores data at the block level, while NAS accesses data as files. To a client OS, a SAN typically appears as a disk and exists as its own separate network of storage devices, while NAS appears as a file server.
SAN is associated with structured workloads such as databases, while NAS is generally associated with unstructured data such as video and medical images. “Most organizations have both NAS and SAN deployed in some capacity, and often the decision is based on the workload or application,” Sinclair says.
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