increase fc max luns on host - Murray-LIANG/forgetful GitHub Wiki

Increase the Max LUNs of FC Host Adapter

In our environment, Emulex LightPulse Fibre Channel Host Adapter (lpfc) is used. For other adapters like QLogic Corp Fibre Channel to PCI Express HBA (qla driver) and Cisco Systems Inc VIC FCoE Host Adapter (fnic driver), please refer to https://access.redhat.com/solutions/26017 or ask for help from RedHat experts directly.

Default value of max LUNs

For lpfc, the default value of max LUNs is 255.

stack@ubuntu-server7:~$ cat /sys/class/scsi_host/host9/lpfc_max_luns
255

If a lun is with HLU number greater than 255, then the host cannot see this lun. And you could see below messages via dmesg:

lun11096 has a LUN larger than allowed by the host adapter

Host OS is Ubuntu

  1. Edit /etc/initramfs-tools/modules, add below lines:
scsi_mod max_luns=16384
lpfc lpfc_max_luns=16384
  1. Update the initramfs:
sudo update-initramfs -u

  1. Reboot the host.

  2. Verify the change effective:

stack@ubuntu-server7:~$ sudo cat /sys/module/lpfc/parameters/lpfc_max_luns
16384

Host OS is RedHat

Refer to https://access.redhat.com/solutions/26017.

The difference is just using different configuration files and the way of generating new initramfs and booting using new initramfs.