What is SAN Storage and How Does it Work?

A Storage Area Network (SAN) is a high bandwidth sub-network, shared storage system. Many IT organizations are debating today whether the benefits of introducing a SAN outweigh the costs involved.

SANs allow organizations to implement standardized methods and tools for security, data protection, and disaster recovery by saving data in centralized shared storage. The aim is to minimize single failure points.


SANs are considered easily accessible and robust. Do you plan to transition away from your current storage strategy to a SAN? Read on to learn about SAN and its functions in modern network environments.

Image Source: Information Age

What Is a Storage Area Network?

SANs seem to be the most common storage networking architecture companies are using to provide high throughput and low latency for business-critical applications.

It is block-based storage, using a high-speed architecture linking servers to their logical disk units (LUNs). A LUN is a collection of blocks configured from a repository of shared storage and presented as a logical disk to the server.


These blocks are partitioned and formatted by the server – usually with a file system – to store data on the LUN much as it does on a local disk drive. SANs account for approximately two-thirds of the overall networked storage market.

A steadily increasing portion of SAN deployments optimizes all-flash storage to obtain its high capacity, consistent low latency, and lower overall cost relative to spinning disks. A well-designed SAN can reliably withstand multiple components or device errors.

How a SAN Works

When a host needs to access a storage device on the SAN, it sends the storage device a block-based access request.


It encapsulates SCSI commands into FC packets. The Host HBA receives the request and converts it from its binary data form to the optical format needed for fiber optic transmission.

At the same time, the request is assembled according to FC protocol rules. The HBA forward the request from the FC to the SAN.

One of the SAN switches receives the request, depending on the connection between the HBA and the fabric switch port, and passes it to the storage processor, which then transfers it to the storage unit.

Image source: SDS Blog

Types of SAN

The most common SAN protocols are as follows.

Fibre Channel Protocol (FCP)

This is the most commonly used SAN or block protocol, applied to 70%-80% of the total SAN market. FCP utilizes Fibre Channel transport protocols with SCSI commands embedded in it.

Internet Small Computer System Interface (iSCSI)

Considered as the second most extensive SAN or block protocol, with a share of nearly 10% to 15%. iSCSI embodies SCSI commands within an Ethernet frame and then employs an IP Ethernet transport network.

Fibre Channel over Ethernet (FCoE)

FCoE is below 5% of the SAN market place.  As it encompasses an FC frame within an Ethernet datagram, it is identical to iSCSI.

It then, like iSCSI, uses an IP Ethernet network for transport.

Non-Volatile Memory Express over Fibre Channel (FC-NVMe)

NVMe is an interface protocol used to access flash storage through a PCI Express (PCIe) bus. It’s unlike conventional all-flash architectures that are restricted to a single, serial queue of commands.

NVMe facilitates tens of thousands of parallel queues, capable of handling tens of thousands of simultaneous commands.

What is SAN Storage and How Does it Work?
Image source: Silverton Consulting


If your data storage needs to be centralized or streamlined, then a SAN storage might be right for you. The SAN equipment price tag could, however, be beyond a small business’s scope. 

Consider how much data you have now and how much new data you are likely to create each month when determining your possible storage requirements.

You need to do your research and consider several aspects before investing in a server, such as things like the programs you will run, space, processor, form factor, etc.