[CentOS] dd disk will not boot - can't find /dev/root

[Les Mikesell]

On Mon, Dec 12, 2011 at 9:51 AM, Joseph Spenner <joseph85750 at yahoo.com> wrote:
> OS= CentOS 5.4, 64bit.
>
> I've always had great luck using dd to copy entire disks, and booting on other systems.  However, I'm having difficulty with a couple systems.  I boot using an install DVD so the OS disk is quiet, and dd to my target disk:
>
> # dd if=/dev/sda of=/dev/sdb bs=1024k
>
> /dev/sdb is the blank disk.  The disks are 2T.  After a few hours the operation is complete.  But when I try to boot the new disk on my other system, I get the following errors after the CentOS boot menu (it counts down to boot the default disk fine, then this error):

If you do much of this, I'd recommend using the clonezilla-live distro
which will automate it and use partclone to avoid having to copy the
unused parts of the disk.

>   (screen shot at   http://img214.imageshack.us/img214/645/centosbooterror.jpg   )
>
> I've read posts regarding the /dev/root error, and they talk about rebuilding initrd.  I've tried some of the fixes mentioned, but have had no success.
> All I can think of is slightly different hardware on the new system where I'm trying to boot, but I'm not sure what the difference could be.
> They're both 64bit SuperMicro systems.
>
> If anyone has any ideas, I'd love to hear.

I suspect the hardware isn't really identical.  Can you boot the
source machine from the copied disk?

-- 
   Les Mikesell
     lesmikesell at gmail.com