Red Hat Knowledgebase

Release Found: Red Hat Enterprise Linux 3, Red Hat Enterprise Linux 2.1

Symptom:
A QLogic fiber channel adapter was added to the server and connected to an external storage array. When the system was booted up, the internal disks on the server originally desginated as /dev/sda, were now designated /dev/sdb while the external disks on the fiber storage were now /dev/sda.

Solution: While examining the /etc/modules.conf file, it was noted that the module for the QLogic adapter was listed before the module for SCSI adapter connected to the server's internal disks:

#cat /etc/modules.conf alias eth0e1000 alias eth1 e1000 alias scsi_hostadapter qla2300 alias scsi_hostadapter1 mptbase alias scsi_hostadapter2 mptscsih alias usb-controller usb-ohci

Since the QLogic module was being loaded before the internal SCSI adapter's modules, the operating system was picking up the disks attached to the fiber adapter as /dev/sda.

To prevent this from happening, the /etc/modules.conf file must be modified so the QLogic module loads after the internal SCSI modules. Example:

alias eth0 e1000 alias eth1 e1000 alias scsi_hostadapter mptbase alias scsi_hostadapter1 mptscsih alias scsi_hostadapter2 qla2300 alias usb-controller usb-ohci

After making this modification and saving the file, you need to rebuild the initrd image.

WARNING: Make Sure you build this against the correct kernel (the kernel you want to run). It is recommend that if you are going to replace your existing initrd image with the new one, that you make a back-up copy first. The -f option will force or overwrite the existing initrd image file.

cp /boot/initrd-2.4.9-e.27smp.img /boot/initrd-2.4.9-e.27smp.img.bak
mkinitrd -f -v /boot/initrd-2.4.9-e.27smp.img 2.4.9-e.27smp

In order for the changes to take effect you will need to reboot your system to the kernel you rebuilt the initrd image for.