Editing World Wide Name

{{Short description|Unique identifier used in storage technologies}}
A '''World Wide Name''' ('''WWN''') or '''World Wide Identifier''' ('''WWID''') is a [[unique identifier]] used in storage technologies including [[Fibre Channel]], [[Parallel ATA]], [[Serial ATA]], [[SCSI]] and [[Serial Attached SCSI|Serial Attached SCSI (SAS)]].<ref>{{Cite web|title=lsscsi(8) — lsscsi — Debian testing|url=https://manpages.debian.org/testing/lsscsi/lsscsi.8.en.html.gz|access-date=2020-09-26|website=manpages.debian.org}}</ref>

A WWN may be employed in a variety of roles, such as a [[serial number]] or for [[addressability]]; for example, in Fibre Channel networks, a WWN may be used as a WWNN (World Wide Node Name) to identify an endpoint, or a WWPN (World Wide Port Name) to identify an individual port on a switch. Two WWNs which do not refer to the same thing should always be different even if the two are used in different roles, i.e. a role such as WWPN or WWNN does not define a separate WWN space. The use of burned-in addresses and specification compliance by vendors is relied upon to enforce uniqueness.

==Formats==
Each WWN is an 8- or 16-byte number, the length and format of which is determined by the most significant four bits, which are referred to as an NAA (Network Address Authority). The remainder of the value is derived from an [[IEEE]] [[Organizationally Unique Identifier|OUI]] (or from Company Id (CID)) and vendor-supplied information. Each format defines a different way to arrange and/or interpret these components. OUIs are used with the U/L and [[multicast]] bits zeroed, or sometimes even omitted (and assumed zero), though CID has U/L set to 1.<ref name="eui">{{cite web|url=https://standards.ieee.org/wp-content/uploads/import/documents/tutorials/eui.pdf|title=Guidelines for Use of Extended Unique Identifier (EUI), Organizationally Unique Identifier (OUI), and Company ID (CID)|website=IEEE Standards Association|publisher=IEEE|access-date=5 August 2018}}</ref>

The WWN formats include:<ref>{{cite web|url=https://standards.ieee.org/wp-content/uploads/import/documents/tutorials/fibre.pdf|title=Guidelines for Fibre Channel Use of the Organizationally Unique Identifier (OUI)|author=IEEE}}</ref>
* "Original" IEEE formats are essentially a two-byte header followed by an embedded [[MAC address|EUI-48]] address (which contains the OUI). The first 2 bytes are either hex 10:00 or 2x:xx (where the x's are vendor-specified) followed by the 3-byte OUI and 3 bytes for a vendor-specified serial number. Thus, the difference between NAA 1 format and NAA 2 format is merely the presence of either a [[Data padding|zero pad]] or an extra 3 [[nibble]]s of vendor information.
* "Registered" IEEE formats dispense with padding and place the OUI immediately after the NAA. The OUI is no longer considered to be part of a EUI-48 address. For NAA 5 format, this leaves 9 contiguous nibbles for a vendor-defined value. This is the same format used by the companion NAA 6 format, the only difference being a 16-byte number space is assumed, rather than an 8-byte number space. This leaves a total of 25 contiguous nibbles for vendor-defined values.
* "Mapped EUI-64" formats manage to fit an EUI-64 address into an 8-byte WWN. Since the NAA is mandatory, and takes up a nibble, this represents a four-bit deficit. These four bits are recouped through the following tricks: First, two bits are stolen from the NAA by allocating NAAs 12, 13, 14, and 15 to all refer to the same format. Second, the remaining two bits are recouped by omitting the U/L and multicast bits from the EUI-64's OUI. When reconstructing the embedded EUI-64 value, the U/L and multicast bits are assumed to have carried zero values.

==Presentation==
WWN addresses are predominantly represented as colon separated hexadecimal octets, MSB-first, with leading zeros — similar to [[Ethernet]]'s [[MAC address]]. However, there is much variance between vendors.<ref>{{cite web
  | author = Richard Butler
  | title = WWN Notes v1.3
  | url = https://community.emc.com/servlet/JiveServlet/previewBody/5136-102-1-18154/WWN_Notes_v1.3.pdf
  | archive-url = https://web.archive.org/web/20130918100626/https://community.emc.com/servlet/JiveServlet/previewBody/5136-102-1-18154/WWN_Notes_v1.3.pdf
 | archive-date = 2013-09-18
 }}</ref>

== Example usage ==

Linux uses WWN to identify disks by providing symbolic links to the real device entry:
<pre>
ls -l /dev/disk/by-id/
[…]
lrwxrwxrwx 1 root root  9 Jul  4 22:00 wwn-0x5002e10000000000 -> ../../sr0
lrwxrwxrwx 1 root root  9 Jul  4 22:00 wwn-0x500277a4100c4e21 -> ../../sda
lrwxrwxrwx 1 root root 10 Jul  4 22:00 wwn-0x500277a4100c4e21-part1 -> ../../sda1
lrwxrwxrwx 1 root root 10 Jul  4 22:00 wwn-0x500277a4100c4e21-part2 -> ../../sda2
lrwxrwxrwx 1 root root 10 Jul  4 22:00 wwn-0x500277a4100c4e21-part3 -> ../../sda3
</pre>
<small>(There are more entries in this directory which are omitted here)</small>

The target names (sr0, sda) might change when new devices are added to the computer (e.g. sda might become sdb) but the WWN will be the same. That is an advantage when the WWNs are used in configuration files and scripts, e.g., {{mono|/etc/[[fstab]]}}.

== How to Find WWN Information in Linux ==
{{how to|section|date=February 2023}}
There are various ways how to find WWN information.<ref>{{cite web|url=https://rsydigitalworld.com/how-to-find-wwn-number-information-in-linux/|title=How to Find WWN Number Information in Linux|website=nixDrafts|author=Raj Rai|date=16 October 2019 |accessdate=29 November 2021}}</ref>

Regardless of HBA type, below commands can be used to find WWN number information.

=== Method 1  ===
 <nowiki>#</nowiki> cat /sys/class/fc_host/host*/port_name
 
 0x10000090fa2537d6
 
 0x10000090fa253a29

=== Method 2 : using syminq command ===
If EMC Storage is being used so there is a chance you must have SYMCLI software installed. syminq comes with SYSCLI. syminq is also helpful in getting WWN in easy way.
 [root@server]# '''syminq hba'''
 Host Name : server
 HBA Type            : FibreChannel
 HBA Name            : Emulex-LPe11000-E-2
 Vendor              : Emulex Corporation
 Model               : LPe11000-E
 Serial Number       : BT01473025
 Firmware Version    : 2.72A2 (Z3D2.72A2), sli-3
 Driver Version      : 8.2.0.63.3p; HBAAPI(I) v2.1.g, 12-07-07
 '''Node WWN            : 20000000c9b0513a'''
 Number of Ports     : 1
 '''Port WWN            : 10000000c9b0513a'''
 Port name           : /sys/class/scsi_host/host3
 Port type           : NPort
 Port FCID           : 2764032
 Port speed          : 4gbit
 Supported speed     : 4gbit
 Port state          : Online
 Supported COS       : 00000008
 Supported FC4 types : 0000010000000001000000000000000000000000000000000000000000000000
 Active FC4 types    : 0000010000000001000000000000000000000000000000000000000000000000
 Max frame size      : 2048

=== Method 3 : using hbacmd command ===
It will work if '''''hbanyware''''' package is installed.
 [root@server]# '''/usr/sbin/hbanyware/hbacmd listHBAs'''
 Manageable HBA List
 Port WWN   : 10:00:00:00:c9:b0:55:2e
 Node WWN   : 20:00:00:00:c9:b0:55:2e
 Fabric Name: 10:00:50:eb:1a:5f:c7:0c
 Flags      : 8000fe00
 Host Name  : server
 Mfg        : Emulex Corporation
 Serial No. : BT01474056
 Port Number: n/a
 Mode       : Initiator
 '''Port WWN   : 10:00:00:00:c9:b0:51:32'''
 '''Node WWN   : 20:00:00:00:c9:b0:51:32'''
 Fabric Name: 10:00:50:eb:1a:5f:bd:0c
 Flags      : 8000fe00
 Host Name  : server
 Mfg        : Emulex Corporation
 Serial No. : BT01472998
 Port Number: n/a
 Mode       : Initiator
 [root@server]#

=== Method 4 : using systool command ===
'''''systool''''' utility comes with Linux distros. If it is not available it can be installed on servers where HBA is already installed.
  # '''systool -c fc_host -v'''
 (output trimmed for clarity)
   Class Device path = "/sys/class/fc_host/host8"    port_name           = "'''10:00:00:00:c9:b0:51:32'''"    node_name           = "'''20:00:00:00:c9:b0:51:32'''"

==List of OUIs commonly seen as WWN Company Identifiers==
OUIs can be queried searching the [https://standards-oui.ieee.org/ IEEE organization's Public Manufacturers OUI list]. OUIs can also be queried by searching IEEE Standards Registration authority [https://regauth.standards.ieee.org/standards-ra-web/pub/view.html#registries].
* 00:10:86 [[ATTO Technology]]
* 00:60:69 [[Brocade Communications Systems]]
* 00:05:1E [[Brocade Communications Systems]], acquired with Rhapsody Networks
* 00:60:DF [[Brocade Communications Systems]], acquired with CNT Technologies Corporation
* 08:00:88 [[Brocade Communications Systems]], acquired with McDATA Corporation. WWIDs begin with 1000.080
* 00:05:30 [[Cisco]]
* 00:05:73 [[Cisco]]
* 00:05:9B [[Cisco]]
* 00:0D:31 [[Dell, Inc.]], for Dell Compellent Storage products
* 00:01:E8 [[Dell, Inc.]], for Dell Force10 Networking Products
* 00:23:29 [http://www.ddrdrive.com/ DDRdrive LLC], for DDRdrive X1
* 00:60:16 [[EMC Corporation]], for CLARiiON/VNX
* 00:60:48 [[EMC Corporation]], for Symmetrix DMX
* 00:00:97 [[EMC Corporation]], for Symmetrix VMAX
* 00:01:44 [[EMC Corporation]], for VPLEX
* 00:00:C9 [[Emulex]]
* 00:60:B0 [[Hewlett-Packard]] - Integrity and HP9000 servers. WWIDs begin with 5006.0b0
* 00:11:0A [[Hewlett-Packard]] - ProLiant servers. Formerly [[Compaq]]. WWIDs begin with 5001.10a
* 00:01:FE [[Hewlett-Packard]] - EVA disk arrays. Formerly [[Digital Equipment Corporation]]. WWIDs begin with 5000.1fe1 or 6000.1fe1
* 00:17:A4 [[Hewlett-Packard]] - MSL tape libraries. Formerly Global Data Services. WWIDs begin with 200x.0017.a4
* 00:0C:CA [[HGST]], a Western Digital Company
* 00:60:E8 [[Hitachi]]
* 00:50:76 [[IBM]]
* 00:17:38 [[IBM]], formerly XIV.
* 00:15:17 [[Intel]]
* 00:A0:98 [[NetApp]]
* 24:A9:37 [[Pure Storage]]<ref>{{Cite web | url=https://www.codyhosterman.com/2016/01/vmfs-snapshots-and-the-flasharray-part-iv-how-to-correlate-a-vmfs-to-a-flasharray-volume/ |title = VMFS Snapshots and the FlashArray Part IV: How to correlate a VMFS to a FlashArray volume|date = 25 January 2016}}</ref>
* 00:E0:8B [[QLogic]] [[Host adapter|HBA]]s, original identifier space
* 00:1B:32 [[QLogic]] [[Host adapter|HBA]]s. new identifier space starting to be used in 2007
* 00:C0:DD [[QLogic]] [[Fibre Channel switch|FC switches]]
* 00:90:66 [[QLogic]] formerly Troika Networks
* 00:11:75 [[QLogic]] formerly PathScale, Inc
* 00:25:38 [[Samsung Electronics]], for [[solid-state drive]]
* 00:1B:44 [[SanDisk]]
* 00:1E:82 [[SanDisk]]
* 00:0C:50 [[Seagate Technology]]
* 00:A0:B8 [[Symbios Logic]]
* 1C:5A:0B [[Tegile Systems]]
* 00:00:39 [[Toshiba]]
* 00:14:EE [[Western Digital]]
* 14:F0:C5 Xtremio ([[EMC Corporation]])
* 00:50:CC [[Xyratex]]
* 57:42:B0 [[Infinidat]], For infinibox
* 00:24:E9 [[Samsung]]

== See also ==
* [[Advanced Technology Attachment|Advanced Technology Attachment (ATA)]]
* [[Fibre Channel]]
* [[Mass Storage Control Protocol]]
* [[Persistent binding]]
* [[Serial Attached SCSI|Serial Attached SCSI (SAS)]]
* [[Switched fabric]]
* [[World Wide Port Name]] (WWPN)

==External links==
*[https://standards-oui.ieee.org/oui/oui.txt IEEE OUI list]

== References ==
{{Reflist}}

[[Category:Computer network technology]]
[[Category:SCSI]]
[[Category:Fibre Channel]]
[[Category:Identifiers]]