Trying to rescue system via grub

cuco76 · 11-02-2007, 02:29 PM

ok....

I have a computer running Nvidia Raid 0. had to reinstall windows and so i wanted to use the rescue cd for my distro (Fedoar 7) to reinstall grub.

Normally, I would do this:

Code:

#grub
#root (hd0,1)
#setup (hd0)

However this is not working. I am guessing it has to do with the Nvidia raid mapping system but i am not sure. In my grub configuration root shows up as (hd0,1) but for some reason grub won't accept it giving errors such as unknown device or filesystems. I will try to get the exact errors.

/boot is /dev/mapper/nvidia_ahdjiajcp3

has anyone ever successfully reinstalled grub in this scenario?

Thanks in advance

cuco76 · 11-02-2007, 02:50 PM

OK so here are some exact error messages:

Code:

root (hd0,1)
filesystem type unknown, partition type 0x83
setup (hd0)
error 17 Cannot mount selected partition

root (hd0,0) gives 0x7 and (hd0,2) gives 0x7 partition types with the same setup error.

if i try to do: (from memory)

Code:

root (hd1,anything)
cannot mount selected something

hope this clarifies

jiml8 · 11-02-2007, 08:49 PM

grub.conf? What is that?

I do believe that your /boot has to be on a partition that is not part of the raid, if you are using software raid or LVM.

The easiest way to find it is to just do an fdisk -l on your drives, and we'll see what that turns up.

cuco76 · 11-04-2007, 11:51 AM

OK so i got it figured out. The reason it worked is unknown to me. However it seems that when your system is using /dev/mapper's instead of /dev/hd* to point to your hardware you have to tell grub that this is the case.

I found this because from the rescue env. a fdisk -l shows up with errors until i pointed it to /dev/mapper/nvidia_whatever.

So i ran "grub --device-map=/boot/grub/device.map" and then was able to restore grub to my mbr. I guess by default grub tries to connect to /dev/hda or sda.

Anyways hope this helps someone else out.

Micro420 · 11-04-2007, 12:15 PM

Thanks for posting the solution. This will come in handy for other people. I guarantee it