Sunday, April 29, 2007

How to detect LUN in RHEL

If Redhat system is not recognizing any LUN other than LUN0, do follwoing.

1. Open the /etc/modules.conf file.

2. For Linux 2.4 kernels, add the following line:
options scsi_mod max_scsi_luns=128

For Linux 2.6 kernels, add the following line:
options scsi_mod max_luns=256

3. Save the file.

4. rebuild the ram-disk associated with the current kernel
cd /boot
mkinitrd –v initrd-kernel.img kernel

5. Restart the host.

Example modules.conf (using vxfs & RedHat included QLogic driver)

options scsi_mod max_scsi_luns=512
alias scsi_hostadapter megaraid2
alias scsi_hostadapter1 qla2300
alias usb-controller usb-uhci
alias usb-controller1 ehci-hcd
alias eth0 tg3
alias eth1 tg3
alias eth2 e1000
alias eth3 e1000
alias eth4 e1000
alias eth5 e1000
insmod_opt=-N # required for vxportal and vxfs
above vxfs fdd vxportal
post-install vxportal (/usr/lib/fs/vxfs/vxenablef -e full;) >/dev/null 2>&1
alias char-major-10-32 vxportal

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