Why do HBAs in a SAN have same base?

Storage expert Chris Poelker outlines WWN basics in order to answer the question: "Why do HBAs in a SAN have same base?"

Why do HBAs in a SAN have same base?
In a SAN, a world wide name (WWN) is a 64-bit identifier for each device in the fabric.

All WWNs are registered with and assigned by the The Institute of Electrical and Electronics Engineers (IEEE)....

This is done to assure each and every WWN is unique. A WWN is similar in concept to a network card's MAC address in an IP network, but is formatted differently.

WWNs are formatted as follows:

WWN= XYYYYYYZ ZZZZZZZZ (Example: 500060E8064183F3)

X = the first 4-bit field, called the NNA, specifies the format the WWN follows. This number is a "5" for storage target ports, and either a "1" or a "2" for an HBA port.

YYYYYY = called the organizational unique identifier (OUI) which is assigned by the IEEE to specific vendors (Such as Qlogic, Emulex, Hitachi, EMC, IBM, etc...) This is why the address in this area always seems to be similar if you are buying from a specific vendor.

ZZZZZZZZZ = the vendor specified identifier (VSI), which is defined by the vendor owning the OUI. These numbers can be changed by the vendor to develop an offset of the node WWN to get a port WWN. As an example, an HBA may have dual ports. The HBA is assigned a node WWN, and an offset is used to get the port WWN for each port on the HBA by changing the value of the VSID.

This was first published in January 2006

Dig Deeper on Fibre Channel (FC) SAN



Find more PRO+ content and other member only offers, here.

Have a question for an expert?

Please add a title for your question

Get answers from a TechTarget expert on whatever's puzzling you.

You will be able to add details on the next page.



Forgot Password?

No problem! Submit your e-mail address below. We'll send you an email containing your password.

Your password has been sent to:



  • Tintri VMstore T5000

    Like all of its VM-aware storage systems, Tintri’s first all-flash array -- the Tintri VMstore T5000 -- allows admins to bypass ...

  • SolidFire SF9605

    The high-capacity SolidFire SF9605 uses SolidFire’s Element OS 8 (Oxygen) to deliver new enterprise features such as synchronous ...

  • HPE 3PAR StoreServ 20850

    HPE 3PAR StoreServ 20850 holds 1,024 solid-state drives (SSDs). Hewlett Packard Enterprise claims it can deliver more than three ...





  • Asigra Cloud Backup Version 13

    Asigra Cloud Backup Version 13 provides an AWS Elastic Block Store Snapshot Manager and the ability to support Docker container ...

  • Veeam Availability Suite v8

    Veeam Availability Suite v8 offers several key backup software components in one package, including Veeam Cloud Connect, Snapshot...

  • Druva inSync 5.5

    Druva inSync 5.5 endpoint backup software stands out with its proactive compliance, cloud app integration, full text search and ...