[CentOS] mount the wrong device after system recovery

Tue Feb 8 21:46:54 UTC 2011
Robert Heller <heller at deepsoft.com>

At Tue, 8 Feb 2011 16:31:32 -0500 CentOS mailing list <centos at centos.org> wrote:

> 
> My grub.conf is pointing to sdb1 for /. I've corrected to use
> /dev/vg0/lv1. But after rebooting, I am getting the same error. I guess
> I need to rebuild initrd.img file. How do I rebuild that file?

The best way to do it *right* is to boot with a rescue system (such as
the installer CD/DVD).  You need to make sure it properly mounts the
necessary file systems, specificly /dev/vg0/lv1 as /sysroot, whatever
you are using for /boot to /sysroot/boot (/boot can't be in the LVM
volume group -- grub cannot deal with that!), then make sute /proc,
/sys, and /dev are mount --bind'd to /sysroot/proc, /sysroot/sys, and
/sysroot/dev.  Then you will chroot to /sysroot and issue a command like:

mkinitrd -f /boot/initrd-2.6.18-194.32.1.el5.img 2.6.18-194.32.1.el5

(replace '2.6.18-194.32.1.el5' with the proper kernel version you will
be booting from -- 2.6.18-194.32.1.el5 is the latest CentOS 5.5 kernel).

exit and reboot.

> 
> Thanks,
> 
> - xinhuan
> 
> -----Original Message-----
> From: centos-bounces at centos.org [mailto:centos-bounces at centos.org] On
> Behalf Of Robert Heller
> Sent: Tuesday, February 08, 2011 2:59 PM
> To: CentOS mailing list
> Cc: CentOS mailing list
> Subject: Re: [CentOS] mount the wrong device after system recovery
> 
> At Tue, 8 Feb 2011 13:51:32 -0500 CentOS mailing list
> <centos at centos.org> wrote:
> 
> > 
> > Content-Class: urn:content-classes:message
> > 
> > 
> > Hi,
> > 
> >  
> > 
> > I am recovering a CentOS 5.4 system. I've copied all partitions into
> the
> > recovery system. I've installed grub boot loader. However, the
> original
> > system is using /dev/sdb1 for root (/), while the recovery system is
> > using LVM (/dev/vg0/lv1) for root (/). When recovery system boots, I
> got
> > the panic error:
> > 
> >  
> > 
> > *         Mounting /dev/sdb1 on /sysroot
> > 
> > *         Mount: mounting /dev/sdb1 on /sysroot failed: No such file
> or
> > directory
> > 
> > *         Mount: mounting /dev on /sysroot/dev failed: No such file or
> > directory
> > 
> > *         * switching / to /sysroot
> > 
> > *         Switch_root: bad newroot /sysroot
> > 
> > *         Kernel panic - not syncing: Attempted to kill init!
> > 
> >  
> > 
> > I've changed the recovery system fstab to use the correct devices. I
> > deleted recovery system etc/lvm/cache/.cache file. But it still
> doesn't
> > work. What am I missing?
> 
> You need to rebuild the initrd and make sure the grub.conf file is
> up-to-date (has the right thing for the root parameter).
> 
> > 
> >  
> > 
> > Thanks,
> > 
> >  
> > 
> > -          xinhuan
> > 
> > MIME-Version: 1.0
> > 
> > _______________________________________________
> > CentOS mailing list
> > CentOS at centos.org
> > http://lists.centos.org/mailman/listinfo/centos
> > 
> >                                                            
> 

-- 
Robert Heller             -- 978-544-6933 / heller at deepsoft.com
Deepwoods Software        -- http://www.deepsoft.com/
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