Adding Storage LUN in Linux

Description or Fiber Chanel Concepts

Fiber Chanel Network is something similar to Computer Networks (802.3 Standards). Fiber Chanel Network also uses Network topology, and it has Seven Layers.

  • Network Topology
  1. FC-Point to Point (FC-P2P): In this topology two devices are connected directly each other.
  2. Arbitrated Loop (FC-AL): In this topology devices are connected in loop or ring, similar to ring topology.
  3. Switched Fabric (FC-SW): In this topology devices are connected to fibre channel switches, similar to computer network switch***
  • Fibre Channel network Layers:

This FC channel Network layer does not follow OSI network model layering, however it                                      has similarly five layers.

  1. FC-0 Media and Interfaces: Covers the physical characteristics of the interface and media, including cables, connectors, drivers, transmitters, and receivers. The FC-0 layer has an analog interface to the transmission medium and a digital interface to the FC-1 layer.
  1. FC-1 Transmission Protocol: Defines how FC-0 signals are patterned to carry data and how port-to-port links are initialized. The FC-1 level describes the means by which user data is encoded for transmission and decoded at the other end.
  2. FC-2 Framing and Signaling Protocol: Defines the rules for signaling and the transfer of data. Defines various classes of services, some examples: Class 1: Is a full-duplex dedicated link between 2 ports. (Highest quality of service because it is the most effective in transferring large amounts of data at very high speed. Class 2: Multiplexed connection, where 1 port can carry different exchanges with many other ports. Class 3: Multicast and broadcast where there’s no confirmation of receipt
  1. FC-3 Common Services: Defines commons services provided by two or more node ports in a host system. (Ex. Two or more node ports, sharing a common port address, which increases the bandwidth available from node port to fabric ports).
  2. FC-4 Protocol Mapping: Formed by series of profiles defining how to map legacy protocols to Fibre Channel. Profiles for protocols like IP, SCSI, for disk drives, and several others are already defined here.


 FC Terminology

  1. Fibre Channel Protocol (FCP) is a transport protocol (similar to TCP used in IP Networks) that predominantly transports SCSI commands over Fibre Channel networks.
  2. Host Bus Adapter (HBA): A host controller, host adapter or host bus adapter (HBA) installed in Server/system which connects host system and storage devices. Also refer to a Fiber Channel interface card. Every HBA has Unique WWN (World Wide Name, 8bytes in size) which is similar to an Ethernet MAC address. There are two types of WWN numbers in HBA. WWNN which is shared by all ports on host bus adapter, and WWPN which is unique to each port.
  3. Logical Unit Number (LUN): Also Known as Logical disk created on SAN. LUN is number use to identify the logical unit, which is a device addressed by the SCSI Protocol or SAN. SCSI LUN is only part of full address

c-part: controller ID of the host bus adapter

t-part: target ID identifying the SCSI target on that bus,

d-part: disk ID identifying a LUN on that target,

s-part: slice ID identifying a specific slice on that disk.


  • FC Additional Information

Fiber Channel Ports

Short Name Descriptive Name Device Type Port Function
N-port Node Port Node port used to connect a node to a Fibre Chanel switch
F-port Fabric Port Switches Switch port used to connect the Fibre Channel fabric to a node
L-port Loop Port Nodes Node port used to connect a node to a Fibre Channel loop
NL-port Node Loop Nodes Node port which connects to both loops and switches
FL-port Fabric + Loop Port Switches Switch port which connects to both loops and switches
E-port Expansion Port Switches Used to cascade fibre channel switches together
G-port General Port Switches General purpose port which can be configured to emulate other port type
U-port Universal port Switches Intial port state on a switch before anything has connected and it changes personality to an operation state (E-port, F-port, fl-port) or a transitional state like a g-port


Above information are sufficient, when you are dealing with Storage(LUN) client side, that is configuring LUN.

 Before configure the New LUN, try to find some basic information as follows.

Step 1: Find out the how many disk are visible to from the server

#fdisk -l 2>/dev/null | egrep ‘^Disk’ | egrep -v ‘dm-‘ | wc -l

Step 2: Find out How many HBA adapter is installed or Configured in server.

#lspci | grep –I FibreOr

To Find the SCSI hosts currently attached to the system

#lsscsi –H

To find how many host bus adapter available

#systool -fc_host –v Or

#ls /sys/class/fc_host

Host0 host1 host3

Find out size of disk assigned

#lsscsi -s
[0:0:0:0]    cd/dvd  PIONEER  DVD-RW  DVR-212D 1.22  /dev/sr0        –
[1:0:0:0]    disk    ATA      ST3320620AS      3.AA  /dev/sda    320GB
[6:0:0:0]    disk    SEAGATE  ST32000444SS     0006  /dev/sdb   2.00TB


#lsscsi -g
[3:0:0:0]    enclosu HP       A6255A           HP04  –         /dev/sg3
[3:0:1:0]    disk    HP 36.4G ST336753FC       HP00  /dev/sdd  /dev/sg4
[3:0:2:0]    disk    HP 36.4G ST336753FC       HP00  /dev/sde  /dev/sg5


#lsscsi -t –list [3:0:2:0]
[3:0:2:0]    disk    fc:0x21000004cf97e385,0x0b10a3  /dev/sde
roles=FCP Target
supported_classes=Class 3



To Get a Vendor, Module and SN of Devices

#scsi_id –page 0x80 –whitelisted –device=/dev/sda SLSI     Logical Volume   394949227760212329

#scsi_id –page 0x80 –whitelisted –device=/dev/sdbSIBM     1818     FAStTSV14408879     Or

#multipath –lOr

#ls –al /de/disk/by-*

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