Pann McCuaig wrote:
> Greetings SL fans,
>
> Sorry for the length of this post, but I'm hoping someone can come to my
> rescue and want to provide sufficient context.
>
> Recently I had a hard drive failure on a Sun X4600 box running SL4.8.
> The box has four drives; the drive that failed was /boot (only). The
> other three drives make up /dev/md0.
>
> The /boot drive was not backed up (headsmack!).
>
> I have created a rescue USB stick based on the System Rescue CD, which
> boots via grub. I can boot the System Rescue CD successfully, and it
> sees /dev/md0, which I can then mount and read from and write to.
>
> I have attempted to create a kernel and initrd image to add to the USB
> stick that will boot the box as if the kernel and initrd image were on
> the failed (and now removed) boot drive.
>
> I built the kernel and initrd image on a box similar to the box with the
> failed hard drive. I replaced /etc/modprobe.conf with the file from the
> target server, and then did 'yum install kernel-largesmp'. I copied all
> the resulting kernel-related files from /boot to the USB stick, as well
> as the appropriate directory from /lib/modules.
>
> I then restored the helper box to its original state.
>
> I booted the System Rescue CD on the target system and copied the
> /lib/modules directory into place on /dev/md0. I fixed up grub/menu.lst
> to have a stanza to boot the newly created SL4 kernel. I rebooted the
> box, and everything seemed to be going swimmingly, until . . .
>
> . . . the booted kernel seems unable to build /dev/md0 and the boot
> process fails.
>
> In the original configuration, the boot drive was /dev/sda, and the
> drives making up the soft RAID partition were /dev/sdb, dev/sdc, and
> /dev/sdd.
>
> The System Rescue CD detects the USB stick as /dev/sda and the three SAS
> drives as sdb, sdc, and sdd. All is well.
>
> It's not clear to me what is going awry with the SL kernel, but as
> the boot verbiage scrolls by, I see /dev/sdc referenced twice, and no
> reference to /dev/sdd. When the kernel attempts to assemble /dev/md0, it
> uses /dev/sda, /dev/sdb, and /dev/sdc and this fails and /dev/md0 cannot
> be mounted and the kernel panics.
>
> Help, please. Suggestions? Thanks.
>
> BTW, I've put both SL4.8 Disc One, and the SL4.8 Live CD on a bootable
> USB stick; both boot successfully, but I was unable to find a way to
> make either one recognize /dev/md0, much less "rescue" me.
>
> Cheers,
>  Pann
>   
If all you lost was /boot, you can probably boot off the install media 
in rescue mode so it mounts things, chroot to /mnt/sysimage/, then 
reinstall the kernel and grub packages as appropriate, make sure grub is 
installed to the MBR or whatever means you use to boot, and reboot.

-Mark

-- 
Mr. Mark V. Stodola
Digital Systems Engineer

National Electrostatics Corp.
P.O. Box 620310
Middleton, WI 53562-0310 USA
Phone: (608) 831-7600
Fax: (608) 831-9591