What is SAN? How the basic SAN environment look like ?

SAN : (Storage Area Network) Centralized administration of Storage devices. A SAN will be equipped with all storage components starting with Harddisks to HBA cards to SAN Switches to Storage Racks. All the storage will be presented as LUN's to servers through iSCSI or FC protocols.


In the above image you are able to see the basic SAN setup in larger enterprises. I will explain it now how the connectivity goes between all the devices.

What are the devices that are needed for a SAN setup?

image 1. SAN BOX (San Device) – It contains more number of disks to accommodate required storage to the other servers in the environment.

2. SAN NETWORK SWITCH – SAN switches are similar to normal switches but their functionality is to process storage traffic.

3.  HBA CARD : Host Bus Adapter is an interface card as NIC which resides in the normal server to initiate storage requests.

4. OPTICAL FIBER CABLES  or RJ45 CABLES : For Communication

How the communication goes now?

1. To assign more storage to the server, first it should have the HBA cards installed in it as well as the the storage devices are also comes with HBA cards by default.

2. These HBA cards are connected to SAN switch using Optical/RJ45 cables from both ends.

3. Storage engineer creates LUN’s and allocates them to servers. Those LUN are identified by the LUN numbers. Before that, every HBA card is having its own WWN (World Wide Number) as MAC address. It is used in giving right/read access to these LUN’s. (Logical Unit Numbers) A LUN is created from an array of hard disks. It will be in any of the size.

4. Once the LUN’s are visible to the server, they can be mounted on to it in different ways because every OS has its own process to mount the LUN’s. After mounting the LUN’s they are visible as LOCAL DISKS on the server (but they ar coming from the storage area network).

image 5. One important point is, in FC SAN’s the data is accessible as BLOCKS with a max speed of 4MBPS, and in iSCSI SAN’s the data is accessible as files with a max speed of 1MBPS.

6. The FC SAN is very costly when compared to iSCSI SAN, because Optical Fiber Cable is used in it instead of RJ45 cable. This is the reason the transfer speed is very high. One advantage of iSCSI than FC SAN is that, it can be accessible from anywhere in the world as it relies on IP for communication as same as normal network. And its very difficult to connect the storage boxes across the world using the Fibre Cable. One it is very costly and it doesn’t rely upon IP. Even though the speed is low in iSCSI SAN, but it is the only one that is preferable in Wide Area Networks.

Some Examples of Storage Boxes are HP Storage Works, 3PAR Storage, EMC Storage etc.

Thats it. I hope this is informative for you. Keep visiting my blog.

Image Courtesy : www.symantec.com, www.wikipedia.org


  1. All articles in your blog are excellent.Keep the good work on

  2. Excellent .....you are doing a gud job

  3. Its easy to understand....keep posting..

  4. Hey...it was really helpfull.

    Thank my Buddy!!

  5. Super, thank you as it looks like a real envirnment. Keep going

  6. your efforts are beyond description. thanks

  7. Hey Super, it very much understadable.

    Thank you


  8. your explamation is clear & much understandable

  9. goog understand for a person new to san


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