[CentOS] booting from copied ext3 software raid fs to normal fs

Sean O'Connell oconnell at soe.ucsd.edu
Sat Sep 24 22:38:00 UTC 2005

On Sat, 2005-09-24 at 14:20 +0200, dan1 wrote:
> Hello.
> I am trying to boot CentOS 4 from a copy of an ext3 software RAID 1 
> filesystem (md) which has been copied to a normal ext3 filesystem (hd). I am 
> almost getting there, exept that the system hangs after booting the kernel.
> I copied the datas from the /boot and / partitions to two similar partitions 
> on the backuped disk with mirrordir (can also be done with cp or dd). I have 
> setup the new disk with grub and I can reach the grub stage 2. It will also 
> boot the kernel properly, but it will hang during the SElinux initialisation 
> (which is disabled). I don't know exactly if it's a mount or SElinux 
> problem.
> Also, it seems that the raid device is trying to be initialised, and I don't 
> have an md but an hd on that drive. This comes probably from the original 
> setup.
> My question is: does somebody know how I can change that behaviour and let 
> linux mount the hd instead of the md coming from the original ?
> Do I need to boot another vmlinuz image or another initrd for it to work 
> properly ? In this case, how could I generate those new images ?
> The output of the boot sequence is the following:
> Mounting sysfs
> Creating /dev
> Starting udev
> Loading raid1.ko module
> md: raid1 personnality registered as nr 3
> Loading jbd.ko module
> Loading ext3.ko module
> md: Autodetecting RAID arrays.
> md: autorun ...
> md: ... autorun DONE.
> md: Autodetecting RAID arrays.
> md: autorun ...
> md: ... autorun DONE.
> md: Autodetecting RAID arrays.
> md: autorun ...
> md: ... autorun DONE.
> Creating root device
> Mounting root filesystem
> kjournald starting. Commit interval 5 seconds
> EXT3-fs: mounted filesystem with ordered data mode.
> mount: error 2 mounting none
> Switching to new root
> SElinux: Disabled at runtime
> SElinux: Unregistering netfilter hooks
> Then, it hangs here undefinitely.
> Here is my menu.lst grub file on the backup disk I want to boot from:
> default=0
> timeout=5
> splashimage=(hd0,0)/grub/splash.xpm.gz
> hiddenmenu
> title CentOS (2.6.9-11.106.unsupported)
>         root (hd0,0)
>         kernel /vmlinuz-2.6.9-11.106.unsupported root=/dev/hda3
>         initrd /initrd-2.6.9-11.106.unsupported.img
> Here is it's fstab:
> none                    /dev/pts                devpts  gid=5,mode=620  0 0
> none                    /dev/shm                tmpfs   defaults        0 0
> none                    /proc                   proc    defaults        0 0
> none                    /sys                    sysfs   defaults        0 0
> /dev/hda1               /boot                   ext3    defaults        0 0
> /dev/hda2               swap                    swap    defaults        0 0
> /dev/hda3               /                       ext3    defaults        0 0
> /dev/fd0                /media/floppy           auto 
> pamconsole,exec,noauto,managed 0 0
> Any help is greatly appreciated.

You could try booting the machine to single user mode. Interrupt the
boot at grub, use 'e' for edit, go to the kernel line, hit 'e', add an s
on the end of the line and hit 'b' to boot. if you can get to single
user mode, then you can try working your way through the various start
up scripts to see what is causing the problem.

Good luck.


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