what is storage area network

SAN, also known as the System Area Network, is a high-speed network that connects and allows shared pools of block level storage to be accessed by dedicated or multiple servers. This network is usually a dedicated network and so does not share network bandwidth by LAN and other similar devices.

Introduced in the early 2000s, SAN was limited to enterprise-class computing. But since then high-speed disk’s cost has decreased vastly, SAN has become an integral part of organizational storage.

It is a kind of network storage or the storage accessible via network.

SAN and the network storage

How a company stores data in a network plays an essential role in determining the company’s health and productivity. With proper network storage, companies can maximize server performance, simplify management of data, back up all the critical data, and be on guard for disasters.

There are three types of network storage – Direct-Attached Storage (DAS), Network-Attached Storage (NAS) and Storage Area Network (SAN). Because of the sharp decrease in the cost, SAN is also becoming more and more popular with small businesses.

SAN simplifies the informational life cycle management. It consistently delivers a secure data transfer infrastructure.

SAN vs client server network?

A SAN work differently than other networks like client-server networks. Let us consider a home network to explain SAN better.

Home networks usually contain users that browse the internet, and it works with a small amount of data that gets generated at different times. Users can also request for resends if the data gets lost.

On the other hand, Storage area networks handle and work with large amounts of data generated in bulk quantities. The data is very precious, and can’t be afforded to be lost.

SAN solutions are available by using two communication technologies – Fibre Channels (FC) and Internet Small Computer Systems Interface (iSCSI). Both these technologies get widely used in SAN. Both have been fighting with each other for the top spot for years.

FC

It became the leading choice for SAN in the mid-90s. Interconnected fiber channel switches belonging to a high-speed network is used to connect the servers and storage.

Critical applications use this type of connection where interruptions in the data flow are not preferred. It provides data rates between 1Gbps and 16Gbps.

iSCSI

iSCSI is an IP based storage networking standard created as the low-cost and low-performance alternative for SAN. It began gathering popularity in the mid-2000s.

It uses Ethernet switches, and instead of using the costly specialized hardware built for storage workloads, it uses physical connections.

The data rates are better when compared with FC. The data rates with iSCSI are of 10Gbps and higher.

Understanding SAN switches

SAN switches get used for the sole purpose of connecting servers and pools of storage. The primary duty for SAN is to move storage traffic.

These switches are mostly FC switches that are compatible with the FC protocol. Most of the SANs are built based on this protocol. The FC switches check the data packet, and it gathers the origin and destination.

The switch then redirects the data packet to the corresponding storage area. As mentioned earlier, high-performance networks make use of these switches.

The switches used by SAN can also be Ethernet-based and deal with IP addresses. These switches are used to deliver traffic to an IP address.

Organizations usually combine one or more switches to build SANs that connect many servers and storage ports, thereby covering a larger area.

Virtual SAN

Virtual SAN or VSAN is a specific aspect of SAN. Wikipedia explains VSAN as “a collection of ports from a set of connected Fibre Channel switches that form a virtual fabric.”

In short, VSAN is a logical partition inside a physical SAN. With this logical partition, VSANs makes it possible to isolate traffic within certain positions of a SAN.

This isolation can be beneficial when there is a problem with one of the partition. Even if there’s some issue in one partition, it can be taken care with little disruption to the other partitions and SAN as a whole.

Usage of VSANs in our network has many benefits, including ease of management and scalability.

Unified SAN

Unified Storage Area Network, based on unified storage, is a type of storage system that grants the privilege of storing files and managing them from a single device.

The device that is used to manage these files is a modified network attaches storage application.

Converged SAN

A converged SAN makes use of common network infrastructure and SAN traffic to eliminate or to reduce the redundant infrastructure. Thus lowering the complexity and reducing the cost.

As mentioned earlier, SAN makes use of Fiber Channels, and data networks are based upon Ethernet. Converged SAN combines these two and adopts FCoE (Fiber Channel over Ethernet). FCoE encapsulates the Fiber channel payloads into Ethernet frames.

Usually, Converged SAN gets based on 10 GB Ethernet. At times to increase throughput, multiple network ports get bonded together.

Pros of SAN

The main advantage of SAN is that data gets considered as a pool of resources that IT can centrally manage and allocate as needed. The other benefits of SAN include,

  1. Storage Virtualization: An individual device is no longer directly linked to the storage capacity. Instead, data gets considered as a pool of resources that can be managed and allocated on an as-needed basis.
  2. Failover protection: The network can operate continuously even if a server crashes, fails or goes offline for maintenance.

Cons of SAN

The main disadvantage of SAN is cost and complexity. The hardware required for SAN is quite costly, and specific skill set is needed to build and manage a SAN.

Conclusion

SAN short for Storage or System Area Network is a high-speed, dedicated, and secure network that connects data storage tools to a larger network. It makes a group or a network of devices accessible to multiple servers.

SAN establishes communication between different computer systems and each other by connecting them to pools of storage using SAN switches. To servers, SAN appears as attached drives thus avoiding network bottlenecks.

Though intended for larger companies, SAN is becoming increasingly popular among small businesses. As the storage demands increase and the implementation cost decreases, many small level companies are moving towards SAN.

Here to decide if your organization needs SAN? The question you have to ask yourself is whether the cost of managing your storage is rising proportionally as the need for storage capacity. If the answer is a big fat yes, then SAN is your best bet and your savior.