The system must be manually configured to automatically load the device drivers for the controllers to which the multipath IO devices are connected within the INITRD. Therefore add the needed driver module to the variable INITRD_MODULES in the file /etc/sysconfig/kernel.

If your system, for example, contains a RAID controller accessed by the cciss driver and multipath IO devices connected to a Qlogic controller accessed by the driver qla2xxx, this entry would look like:

   INITRD_MODULES="cciss"
  

Because the Qlogic driver is not automatically loaded on start-up, add it here:

   INITRD_MODULES="cciss qla2xxx"
  

After having changed /etc/sysconfig/kernel, recreate the INITRD on your system with the command mkinitrd.

When you are using LILO as a boot manager, reinstall it with the command /sbin/lilo. No further action is required if you are using GRUB.