[CentOS] Creating the symbolic links in the /boot and /boot/grub/

Thu Mar 10 15:43:05 UTC 2011
Simon Matter <simon.matter at invoca.ch>

> Well, I have the disks in hand - all 4, but there is the
> overriding level of apprehension.  Is there a reference to what I
> should do *if* I cannot reboot that I should read?

As I said before, you may need to run grub-install, but I don't know for
sure. And then, you have to know where to install grub, and I don't know
where you have installed it. In fact I don't know how we could know
because it really depends on how your BIOS boots the box. It can be that
it's installed into the MBR of /dev/hdc, then you should be able to
install it using 'grub-install /dev/hdc'. But, since the disk is named
/dev/hdc, it's most likely that there is also /dev/hda and /dev/hdb, and
then it's also likely that grub has been installed into the MBR of
/dev/hda. Who knows?

That said, check disk 1 by putting it into another computer, and chose
'linux rescue' at the boot prompt. Then it will boot using a root
filesystem in ram, and configure network if you want and then tries to
find any CentOS installation in the disks, and mount them if it finds one.
Maybe it wont find one but it should find it on your server. Then it will
mount it as something like /mnt/sysimage. You can then 'chroot
/mnt/sysimage' and fix things.

Good luck!
Simon

>
> Also, after reading the responses to my query about using FAT32
> to store data, I decided to follow the suggestions to use Samba
> to copy the data that needs to be shared with others to my
> Windows connected NTFS external.  So, I am in the process of
> doing that first even though I have an ext3 backup of the same data.
>
> Preparing to jump as I look for my spare parachute....
>
> Todd
>
> On 3/10/2011 2:15 AM, Simon Matter wrote:
>>> Unfortunately, I live out with the cows, so I am using DSL to
>>> download the latest - it will take awhile.  It has been awhile
>>> since I downloaded the four disks, however I assume disk 1
>>> contains all that I need to do a "rescue".
>> Yes that's correct, you need to download only disk 1.
>>
>>> Once I get that down, I will use torrent to get all four disks.
>>>
>>> Hey, guys, many thanks.  Any of you live in the SF Bay Area?
>>> Love to treat you to a beer.
>> Thanks, but it may be a bit difficult. Just let us know if you have been
>> able to boot successfully.
>>
>> Simon
>>
>>> Todd
>>>
>>> On 3/9/2011 1:03 PM, Simon Matter wrote:
>>>>> And here are the contents of grub.conf:
>>>>>
>>>>> # grub.conf generated by anaconda
>>>>> #
>>>>> # Note that you do not have to rerun grub after making changes to
>>>>> this file
>>>>> # NOTICE:  You have a /boot partition.  This means that
>>>>> #          all kernel and initrd paths are relative to /boot/, eg.
>>>>> #          root (hd0,0)
>>>>> #          kernel /vmlinuz-version ro root=/dev/VolGroup00/LogVol00
>>>>> #          initrd /initrd-version.img
>>>>> #boot=/dev/hdc
>>>>> default=0
>>>>> timeout=5
>>>>> splashimage=(hd0,0)/grub/splash.xpm.gz
>>>>> hiddenmenu
>>>>> title CentOS (2.6.9-100.EL)
>>>>>        root (hd0,0)
>>>>>        kernel /vmlinuz-2.6.9-100.EL ro
>>>>> root=/dev/VolGroup00/LogVol00 rhgb quiet
>>>>>        initrd /initrd-2.6.9-100.EL.img
>>>> OK, the file listing of /boot from your last mail and now grub.conf,
>>>> they
>>>> look quite good. grub.conf has been updated by the kernel update, and
>>>> also
>>>> a new initrd-2.6.9-100.EL.img has been created, so that doesn't look
>>>> bad.
>>>>
>>>> The only thing I'm not really sure is if grub is installed correctly
>>>> now.
>>>> Maybe you have to run grub-install again to be sure but I'm just not
>>>> so
>>>> sure about grubs internals. Maybe someone can tell you more about
>>>> this.
>>>>
>>>> As someone else mentioned, it's a very good idea to have a current
>>>> CentOS
>>>> 4.8 disk at hand so you could boot into rescue mode with 'linux
>>>> rescue'
>>>> at
>>>> the boot prompt if somethings goes wrong.
>>>>
>>>> Simon
>>>>
>>>>> Todd
>>>>>
>>>>> On 3/9/2011 12:23 AM, Simon Matter wrote:
>>>>>>> I inadvertently missed using the list...here are my recent
>>>>>>> messages.
>>>>>> As Nico suggested, download the kernel but also grub and
>>>>>> redhat-logos,
>>>>>> like so
>>>>>> wget
>>>>>> http://mirrors.kernel.org/centos/4.9/updates/i386/RPMS/kernel-2.6.9-100.EL.i686.rpm
>>>>>> wget
>>>>>> http://mirrors.kernel.org/centos/4.9/os/i386/CentOS/RPMS/redhat-logos-1.1.26-1.centos4.4.noarch.rpm
>>>>>> wget
>>>>>> http://mirrors.kernel.org/centos/4.9/os/i386/CentOS/RPMS/grub-0.95-3.8.i386.rpm
>>>>>>
>>>>>> Then do a
>>>>>>
>>>>>> rpm -Uvh --replacepkgs --replacefiles kernel-2.6.9-100.EL.i686.rpm
>>>>>> redhat-logos-1.1.26-1.centos4.4.noarch.rpm grub-0.95-3.8.i386.rpm
>>>>>>
>>>>>> And the show us the contents of 'ls -laR /boot' and 'cat
>>>>>> /etc/grub.conf'
>>>>>>
>>>>>> Simon
>>>>>>
>>>>>>> On 3/8/2011 8:39 PM, Nico Kadel-Garcia wrote:
>>>>>>>> On Tue, Mar 8, 2011 at 11:31 PM, Todd
>>>>>>>> Cary<todd at aristesoftware.com>
>>>>>>>> wrote:
>>>>>>>>> reinstall is not an option for yum.  I ran "yum install kernel"
>>>>>>>>> and
>>>>>>>>> it
>>>>>>>>> completed without errors however there are no links created.
>>>>>>>> Oh, dear. Can you grab the RPM and do "rpm -U -replacepkgs
>>>>>>>> [kernel-whatver].rpm"? You should be able to use "yum remove" on
>>>>>>>> the
>>>>>>>> old kernel packages, consistent with freeing up the space, and now
>>>>>>>> install your new kernel with yum.
>>>>>>>>
>>>>>>>>> Would this be the correct ln command for vmlinuz-2.6.9-89.35.1
>>>>>>>>>
>>>>>>>>> # /boot/vmlinuz-2.6.9-89.35.1 /boot/vmlinuz
>>>>>>>>>
>>>>>>>>> Todd
>>>>>>>>>
>>>>>>>>> On 3/8/2011 7:04 PM, Nico Kadel-Garcia wrote:
>>>>>>>>>> On Tue, Mar 8, 2011 at 9:58 PM, Todd
>>>>>>>>>> Cary<todd at aristesoftware.com>
>>>>>>>>>> wrote:
>>>>>>>>>>> I started a new thread since the original one is getting rather
>>>>>>>>>>> long.
>>>>>>>>>>>
>>>>>>>>>>> I have retrieved the files I deleted in /boot and /boot/grub,
>>>>>>>>>>> however I need to make links for
>>>>>>>>>>>
>>>>>>>>>>> /boot/System.map  (System.map ->
>>>>>>>>>>> System.map-2.6.9-89.35.1)
>>>>>>>>>>> /boot/vmlinuz  (vmlinuz ->       vmlinuz-2.6.9-89.35.1)
>>>>>>>>>>> /boot/grub/menu.lst (menu.lst ->       ./grub.conf)
>>>>>>>>>> Instead, re-install your kernel. "yum reinstall kernel". This
>>>>>>>>>> should
>>>>>>>>>> regenerate your symlinks correctly, except possibly the
>>>>>>>>>> grub.conf.
>>>>>>>>>>
>>>>>>>>>>> If it was not so important to get it correct, I would
>>>>>>>>>>> appreciate
>>>>>>>>>>> the syntax for the command.  Usually I would figure it out.
>>>>>>>>>>>
>>>>>>>>>>> Since I have restored the files (I will double check to make
>>>>>>>>>>> sure
>>>>>>>>>>> they are all there), do I need to run grub-install?
>>>>>>>>>> i think yes. The old location of the boot loader is listed in
>>>>>>>>>> /boot/grub/grub.conf, and should be used as the argument to that
>>>>>>>>>> command. grub is much smarter than LILO used to be, but I think
>>>>>>>>>> the
>>>>>>>>>> bootstrap procedure relies on knowing details of where the
>>>>>>>>>> fiddly
>>>>>>>>>> bits
>>>>>>>>>> of grub live on the relevant ex2 compatible filesytem.
>>>>>>>>>>
>>>>>>>>>>> My apologies for bothering everyone with such a dumb error on
>>>>>>>>>>> my
>>>>>>>>>>> part.
>>>>>>>>>>>
>>>>>>>>>>> Todd
>>>>>>>>>>>
>>>>>>>>>>> --
>>>>>>>>>>> Ariste Software
>>>>>>>>>>> Petaluma, CA 94952
>>>>>>>>>>>
>>>>>>>>>>> http://www.aristesoftware.com
>>>>>>>>>>>
>>>>>>>>>>> _______________________________________________
>>>>>>>>>>> CentOS mailing list
>>>>>>>>>>> CentOS at centos.org
>>>>>>>>>>> http://lists.centos.org/mailman/listinfo/centos
>>>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> Ariste Software
>>>>>>>>> Petaluma, CA 94952
>>>>>>>>>
>>>>>>>>> http://www.aristesoftware.com
>>>>>>>>>
>>>>>>>>>
>>>>>>> --
>>>>>>> Ariste Software
>>>>>>> Petaluma, CA 94952
>>>>>>>
>>>>>>> http://www.aristesoftware.com
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> CentOS mailing list
>>>>>>> CentOS at centos.org
>>>>>>> http://lists.centos.org/mailman/listinfo/centos
>>>>>>>
>>>>>> _______________________________________________
>>>>>> CentOS mailing list
>>>>>> CentOS at centos.org
>>>>>> http://lists.centos.org/mailman/listinfo/centos
>>>>>>
>>>>>>
>>>>> --
>>>>> Ariste Software
>>>>> Petaluma, CA 94952
>>>>>
>>>>> http://www.aristesoftware.com
>>>>>
>>>>
>>> --
>>> Ariste Software
>>> Petaluma, CA 94952
>>>
>>> http://www.aristesoftware.com
>>>
>>
>>
>
> --
> Ariste Software
> Petaluma, CA 94952
>
> http://www.aristesoftware.com
>