Re: Copying an rhel as 3 installation from a PowerEdge 2650 to a 2950

On Tue, 2007-04-10 at 14:47 -0700, Gene wrote:
> Hola,
> 
>   I'm tasked with adding a fourth system to an Oracle cluster, and a
> requirement is that it's at the same patch level.  I have been unable
> to find a redhat utility to take care of this, so rather spend time in
> RPM hell I decided to do file systems dumps of one of the cluster
> nodes and load it up on the other box. I copied an install from a
> PowerEdge 2650 to a 2950.
> 
>   These systems use different RAID controllers for the boot disk.
> Because of this I have to load a new driver/module (megaraid_sas).
> But, it is not working.  When I try to boot I get: 
> 
> VFS: Cannot open root device "LABEL=/" or 00:00
> Please append a correct "root=" boot option
> Kernel panic: VFS: Uname to mount root fs on 00:00
> 
>   I'm assuming that the megaraid_sas module is not being loaded.  If I
> do a fresh install from CD I can get the driver installed.  How does
> Redhat load kernel modules?  Because the system panics I can't scroll
> back to to verify what hardware is recognised. 
> 
For RHEL3 the kernel modules are defined in /etc/modules.conf and would
typically have a line that looks something like:

alias scsi_hostadapter megaraid

If you just want to fix your 2950 to boot with the megaraid_sas driver
the easiest way is to simply boot a RHEL3 CD in rescue mode.  The rescue
mode should find your installation and mount it under /mnt/sysimage and
dump you to a prompt.  From there you can run "chroot /mnt/sysimage" and
then edit your /etc/modules.conf file to change the driver.

Then you'll need to rebuild the initrd image so that it actually
includes the new driver by running a command like
"mkinitrd /boot/initrd-2.4.21-47.0.1.EL.img 2.4.21-47.0.1.EL" obviously
substituting your specific kernel versions.

So, to summarize boot rescue CD, modify /etc/modules.conf, rebuild
initrd and reboot.  I can give you more specific instructions if you
need them.

Later,
Tom



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