some useful commands around fibre channel

# for i in $(ls -d /sys/class/scsi_host/host*/device/fc_host/host*/port_name); do echo $i $(cat $i);done

e.g.

# for i in $(ls -d /sys/class/scsi_host/host*/device/fc_host/host*/port_name); do echo $i $(cat $i);done
/sys/class/scsi_host/host15/device/fc_host/host15/port_name 0x2100f4e9d455702c
/sys/class/scsi_host/host16/device/fc_host/host16/port_name 0x2100f4e9d455702d
/sys/class/scsi_host/host17/device/fc_host/host17/port_name 0x2100f4e9d45573c8
/sys/class/scsi_host/host18/device/fc_host/host18/port_name 0x2100f4e9d45573c9

according to The Geek Diary

• To check the available HBA ports :

# systool -c fc_host
Class = "fc_host"

  Class Device = "host2"
    Device = "host2"

  Class Device = "host3"
    Device = "host3"

• To find the WWNs for the HBA ports :

# systool -c fc_host -v | grep port_name
    port_name           = "0x500143802426baf4"
    port_name           = "0x500143802426baf6"

• To check the state of the HBA ports (online/offline) :

# systool -c fc_host -v | grep port_state
    port_state          = "Online"
    port_state          = "Online"

multipathd is not only the the multipath daemon itself, but also a useful command for analysing the SAN:

# multipathd --help

ordinarily you just use the rescan-scsi.sh command. thus, this only reads the configuration again, but does not reinitialize the HBA.

this can be done by:

# echo "1" > /sys/class/fc_host/host<X>/issue_lip

replacing '<X'> with the number of the HBA.

thanks to Veritas