Urgent Help Needed for Boot Problems After Data Restoration

[Rick Stevens]

On 11/18/2009 11:34 AM, Mr. Teo En Ming (Zhang Enming) wrote:
> On Thu, Nov 19, 2009 at 3:06 AM, Rick Stevens<ricks at nerd.com>  wrote:
>> On 11/18/2009 10:33 AM, Mr. Teo En Ming (Zhang Enming) wrote:
>>>
>>> Hi All,
>>>
>>> After restoring data from a backup image set for a 500GB harddisk to a
>>> 1000 GB harddisk, I am unable to boot up my F11 OS. I have already
>>> restored *both* the MBR backup and the dump output from sfdisk.
>>>
>>> What else is missing? I am stuck at a blinking cursor at the top left
>>> corner of the screen. GRUB is not loading and I am unable to select
>>> any kernel to boot.
>>>
>>> Using System Rescue CD, I am able to activate all the logical volumes
>>> and all the volume groups that were restored. I am also able to mount
>>> all the logical volumes and access the restored filesystems.
>>>
>>> So I think the filesystems are restored properly. So I think it is the
>>> problem with MBR, sfdisk dump output restoration, or GRUB. Is there a
>>> problem with restoring data of a 500 GB harddisk to a 1 TB harddisk?
>>
>> Well, let's see...the geometry between the two disks are going to be
>> different so the partition table's going to be screwed up.  That may
>> cause an issue with grub.  It's always dangerous to use block-level
>> backups and restores when the drives are of different sizes or geometries.
>>
>> I'd recommend you boot off the DVD in rescue mode, then use fdisk and
>> the other tools to verify that the partition tables are in good shape.
>> You should also probably fsck each filesystem just to make sure.  Once
>> all that's done, you may have to rebuild the grub environment:
>>
>>         chroot /mnt/sysimage
>>         grub-install /dev/sda   (or whichever disk it is)
>>         exit           (gets out of the chroot)
>>         exit           (gets out of the rescue boot)
>>
>> Pop the DVD out and try to boot again.  That may fix it.
>
> Hi,
>
> If I want to use grub-install, I have to mount the partitions on the
> restore harddisk and then chroot into the mount?

Yes, that's correct.  When the rescue boot comes up and asks if you
want the filesystems mounted, answer "yes".

> Because earlier I have used the interactive grub prompt method without
> mounting filesystems on the restore harddisk and chrooting.

That works too.  Some people get freaked out by the terminology used
by grub in interactive mode, so I tell them to use the method I
mentioned.  It's a bit less intimidating to the newbie.

You aren't one of those people and you seem to have solved it, so
congratulations!  Well done!
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- Rick Stevens, Systems Engineer                      ricks at nerd.com -
- AIM/Skype: therps2        ICQ: 22643734            Yahoo: origrps2 -
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-                    I doubt, therefore I might be.                  -
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