Grub issues

[Frank DiPrete]

jesse205 at gmail.com wrote:
> The partition sda1 had been windows at one point, but I reinstalled 
> windows on a sdb (not today). The partition sda3 has always been the 
> ubuntu partition (a monolithic system as far as mount points). I guess 
> the issue is that today I reformatted sda1 to use as /var/backup and so 
> I wiped out that original MBR?
> 
> Do I really need to reinstall Ubuntu on sda3? I'm mostly afraid of 
> losing the system, I do have a backup but its kinda pieced together and 
> I think it could end up being painful for me if I had to reinstall...
> 
> I'm pretty familiar with using the installation disc, I know what you 
> mean about not letting it format anything. But, what will happen if I 
> reinstall over the existing installation?
> 
> Isn't there a way to use the live CD just to repair the MBR?

yes.

boot into repair / rescue mode
type grub
type setup (hd0)



> 
> Thanks,
> 
> 
> 
> On Mar 18, 2009 6:51pm, Jerry Feldman <gaf at blu.org> wrote:
>  > I have fixed this on several occasions, mostly by my own tinkering.
>  >
>  >
>  > In the past, what I did was to reinstall without formattting.
>  >
>  >
>  > One question, is /boot part of your regular root file system (eg. 
> /dev/sda3) or was it originally /dev/sda1. Remember the /boot grub 
> stage2 must reside within the first 1024 cylinders. It is normally 
> prudent to keep it in the first physical partition although not 
> required. Essentially the MBR must be able to record the physical 
> address of the grub stage 2. Also note that in a reinstall, you don't 
> need to reinstall and overwrite anything. You just want to force a 
> reinstall of grub. This will also install your kernels in the right place.
>  >
>  >
>  >
>  >
>  >
>  > I don't know what your super-grub-disc did, but I've always used the 
> original installation CD/DVD I used to install the system in the first 
> place.  The one important thing to remember is that if you do not have a 
> separate /home partition, to make sure you do NOT format the root file 
> system. Also note that the preferred name of menu.lst is now grub.conf, 
> but several distros, such as ubuntu use menu.lst with no grub.conf, 
> others have grub.conf with menu.lst as a symlink.
>  >
>  >
>  > Again, let me reiterate, when you go to the manual partition menu, 
> make sure you do not have format checked. It's been a whil since I have 
> used this procedure on my laptop since I've taken the upgrade install 
> path. I forget if ubuntu actually gives you access to the packages you 
> want to install. If so, make sure that grub is to be reinstalled, but 
> you don't have to worry about other stuff. It should not deinstall stuff 
> you already have. You may also be able to fix things directly from your 
> live CD, but the main issue is to be able to rebuild the MBR. You can 
> later add the Windows boot section or let the installer set that up for 
> you.
>  >
>  >
>  >
>  >
>  >
>  > On 03/18/2009 12:33 PM, Jesse Lazar wrote:
>  >
>  >
>  >
>  >
>  > Hello,
>  >
>  >
>  >  I kinda hosed my boot loader, was wondering if anyone could point me 
> in the direction of putting the pieces back together.
>  >
>  >
>  >  The computer is my desktop pc. I have two drives: the first has four 
> partitions and the second has only one.
>  >
>  >
>  >  sda1 is 10GB, ext3, unused
>  >
>  >
>  > sda2 is 130GB, NTFS, storage of files (shared with windows)
>  >
>  >
>  > sda3 is 10GB, ext3, this is where the Ubuntu system lives
>  >
>  >
>  > sda4 is 1GB, swap
>  >
>  >
>  >  sdb is 20GB, this disk has windows on it
>  >
>  >
>  >  I re-installed grub a couple times as I was not able to boot my 
> Ubuntu system directly, was having to use a "super-grub-disc" (this is 
> after re-mapping the drives in grub so I could boot windows). Whatever I 
> did last I acutally wiped out the grub installation, there is no 
> "menu.1st" or kernel on sda3.
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>  >
>  > --
>  >
>  >
>  > Jerry Feldman gaf at blu.org>
>  >
>  >
>  > Boston Linux and Unix
>  >
>  >
>  > PGP key id: 537C5846
>  >
>  >
>  > PGP Key fingerprint: 3D1B 8377 A3C0 A5F2 ECBB  CA3B 4607 4319 537C 5846
>  >
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> 
> 
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