*With daily increasing complexity of network systems and global corporate solutions, the world needed technologies that would give impetus to the revival of corporate data storage systems. And SAN technology (Storage Area Network) brought previously unseen performance, tremendous scalability and outstanding total cost of ownership advantages, combined with excellent safety for users.*

![](https://i.imgur.com/MZzqYxQ.jpg)

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**Storage Area Network** - is a system consisting of the actual storage devices, media data and servers connected to it.

![](https://i.imgur.com/DZeG9rm.jpg)

An example of highly reliable infrastructure, which includes servers simultaneously in a local area network (left) and storage area network (right). This scheme provides access to data that is kept in storage, in a case of failure of any of the CPU module, switches, or access path.

# SAN provides:
• centralized resource management of servers and storage systems;
• adding new storage arrays and servers without interrupting an operation of the entire storage system;
• using previously acquired equipment, together with new data storage devices;
• prompt and reliable access to data storage devices located at a great distance from the server;
• accelerating the process of backup and data recovery.

# SAN Architecture

SAN is a high-speed data transmission network, intended to connect servers to storage devices. A variety of SAN topology (point-to-point, arbitrated Loop and commutation) replace traditional tire compounds "server - storage" and provide great flexibility, performance, and reliability.

![](https://i.imgur.com/KzovnXU.gif)

The SAN concept provides connectivity of servers with any storage device working with Fibre Channel protocol. The principle of the interaction of components in the SAN with point-to-point or commutation topologies is shown below.


- **Commutation**

 ![](https://i.imgur.com/8KACwuq.jpg)

- **Point to Point**

![](https://i.imgur.com/ZQqiR3t.jpg)

In the SAN with Arbitrated Loop topology data is transferred sequentially from node to node. To start transferring data transmission device initiates arbitration for the right to use the data environment.


- **Arbitrated Loop**

![](https://i.imgur.com/c4hba6e.jpg)

# SAN Components

*SAN components are divided into the following:*
- Host Bus Adaptors (HBA);
- Storage resources;
- Devices that implement the SAN infrastructure;
- Software.

![](https://i.imgur.com/MgFP143.jpg)

**Host Bus Adaptors**

HBA is installed in the server and carry out its interaction with the SAN by protocol Fibre Channel.

**Storage Resources**

Storage resources include disk arrays, tape drives, and libraries with Fibre Channel interface. The disc can perform data replication over networks between through the Fibre Channel set, and tape libraries can implement the transfer of data to tape directly from the disk array with the Fibre Channel interface, bypassing the network and servers (Serverless backup).

**Devices that implement the SAN infrastructure**

Devices that implement the SAN infrastructure are the Fibre Channel switcher, hubs, and routers. Hubs are used to connect devices operating in the Fibre Channel Arbitrated Loop (FC_AL) mode.

All modern SAN are built on switchers that allow implementing a full network connection. The switchers can not only connect devices through Fibre Channel but also to differentiate access between devices, which switches to create the so-called zone.

![](https://i.imgur.com/6q04JZx.gif)

**Software**

The software allows to backup servers access paths to the disk arrays and dynamic load balancing between routes.

# Used protocols

*The storage area networks use low-level protocols:*

- Fibre Channel Protocol (FCP), SCSI traffic goes through Fibre Channel.
- iSCSI, SCSI traffic goes through TCP / IP.
- FCoE, FCP / SCSI traffic goes through the "pure" Ethernet.
- FCIP and iFCP, encapsulation and FCP / SCSI transfer of IP packets.
- HyperSCSI, SCSI traffic goes through Ethernet.
- FICON traffic goes through Fibre Channel.
- ATA over Ethernet, traffic goes through Ethernet.
- SCSI and / or TCP / IP traffic goes through InfiniBand (IB).

![](https://i.imgur.com/RlVYRjh.gif)

# Benefits

- High reliability of data accesses located on external storage systems.
- Centralized data storage.
- Convenient centralized management and data commutation.
- High performance and low latency.
- Scalability and flexibility of SAN logical structure
- Ability to effectively distribute resources among servers.
- Simple backup scheme - all the data is in one place.
- High degree of SAN security.

![](https://i.imgur.com/KNvXD22.gif)

# Disadvantages

All cons are connected with the high cost of such solutions.

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*Generally speaking, SAN architecture is aimed at resolving the problems caused by intensive backup procedures and exchange of data by transferring the entire system in a dedicated subnet. Based on Fibre Channel protocol SAN systems can widely change the storage capacity of the system and ensure higher bandwidth within the selected subnet.*

*Today, Storage Area Network is an already familiar technology that will continue to evolve and being used by corporate customers in Europe and the US, as well as individuals.*

Check these references if you want to learn more about this technology: [1](https://en.wikipedia.org/wiki/Storage_area_network), [2](http://www.sqlservercentral.com/articles/Miscellaneous/asanprimer/1913/), [3](http://www.snia.org/education/storage_networking_primer/san/what_san)
Please also don't hesitate to leave a comment under this post, where you  can express your opinion or probably give some references to other amazing technologies.

*[Follow me](https://steemit.com/@krishtopa), to learn more about **popular science**, **math** and **modern technologies***

**With Love,
Kate**

Image credit: [1](http://www.cnews.ru/reviews/free/security2004/ebusiness/index6.shtml), [2](http://flylib.com/books/en/2.116.1.18/1/), [3](https://support.software.dell.com/de-de/appassure/kb/118153), [4](http://shopitdirect.com/cms.php?id_cms=18), [5](http://sani-technology.com/sites/expo.html), [6](http://www.sqlservercentral.com/articles/Miscellaneous/asanprimer/1913/), [7](http://wikipedia.qwika.com/en2ru/Arbitrated_loop), [8](http://communicarets.com/point-to-point/)