Re: Newb Needs Help with Boot Recovery

[Dale R. Worley]

zcorker <address@hidden> wrote:
> I am wondering if someone can offer some advice on how to configure my
> system, so that I can bootup?  I am getting an error message when
> running Lubuntu recovery tool (2013 vintage), indicating that "please
> enable a repository containing the [grub2] package in the software
> sources for Centos release 6.7 (sda2).  Then try again.".  A review of
> my Centos files in Lubuntu indicates I am running Grub, and nog Grub
> 2, so I assume my recovery disk isn't capable of supporting grub, but
> I don't know.  The reason there is a boot issue is because I had
> replaced a drive and power supply after they had failed.  I had tarred
> over the files from the failing drive to the new 2 TB SSD, and I have
> run triple boot between Debian, Win XP, Centos, with no problem at
> all.  What would be the easiest way to fix the computer?

I'm no expert in this, but the obvious thing is to try is to do whatever
is needed to "enable a repository containing the [grub2] package in the
software sources for Centos release 6.7 (sda2)", and then try again.

Of course, it may not be possible to do that, and that's what you're
asking about.

You write, "I have run triple boot between Debian, Win XP, Centos, with
no problem at all.", I assume you mean that you did that *in the past*
but don't have it working now.  If you've got a boot on the drive that
works, but you need to get it to boot Ubuntu (if I understand
correctly), the easiest way is to get access to the disk and edit the
grub2.cfg file to add another "menuentry" section to start Ubuntu.

What I use for recovery is Knoppix.  It's a standalone Linux/Gnu system
that runs from a CD or USB storage (much faster).  The disadvantage is
that you've got to be a sysadmin to use it, you need to know at a fairly
low level what you need to do.  See www.knopper.net to download it.  One
caveat:  When Knoppix starts, it doesn't automatically see LVM
partitions of disks.  To see them, do "sudo vgscan; sudo vgchange -ay".

The way I'd fix the problem is to run Knoppix, and in it, run the Grub
command to install a complete Grub2 boot system on your SSD.  That
process is weakly documented, but it's reasonably simple using the
grub2-install command.  The details are in the Grub2 manual (accessible
via the Info system (e.g., Emacs C-h i) under the "Grub" menu entry).
The basic command is:

    grub2-install /dev/sd[whatever]

That installs the boot record on sd[whatever], puts part 1.5 either in
the hidden blocks between the boot record and the first partition, or in
the special "BIOS boot partition" partition (if it exists).  It puts
part 2 in whatever is mounted as /boot on the currently running system
(so make sure that directory is on sd[whatever]) and tells part 1.5 how
to find part 2.  Of course, that won't be true in a recovery situation,
so to put part 2 in Ubuntu's /boot, mount the Ubuntu root partition
somewhere and add the option "--boot-directory=[where U. root part. is
mounted]/boot"

If you want to put part 2 in a separate partition, mount that partition
somewhere on the current system and add the option
"--boot-directory=[partition's directory]".

Dale