boot loader not installed

Thu Oct 29 03:35:39 UTC 2009

  >SATA RAID is set up by the BIOS so you do not need to insmod anything.<

 This is not true. While it is true that SATA RAID is setup within the BIOS, you still need drivers to tell the OS how to access the physical sectors across the individual drives. After installing Ubuntu on my SATA RAID, booting failed because the kernel says that it cannot locate the root file system. The error basically says the partition table indicates the root fs drive takes more sectors than are physically present on the disk. It is a 3 disk RAID5 with 3x 150GB WD Raptors. If I shift-pgup through the kernel output, it is seeing the 3 drives as sda, sdb, and sdd but not as 1 drive. During the live cd install, it saw the SATA RAID as a single 300GB drive and could read and mount the NTFS file system, that I let it overwrite to install Ubuntu on. 

The install recognized the raid5 as /dev/mapper/nvidia_fhgbbaae1. Using the tips you gave, I figured out how to mount this file system and chroot. I used this procedure as listed in the install guide:
mount -t auto /dev/mapper/nvidia_fhgbbaae1 /media/raid -o acl,user_xattr
mount --bind /dev /media/raid/dev
chroot /media/raid

One obvious problem is that the folder /dev/mapper/ does not exist on this file system and there is no device nvidia_fhgbbaae. This device should contain
/dev/mapper/nvidia_fhgbbaae1 mounted as /
/dev/mapper/nvidia_fhgbbaae5 mounted as swap
/dev/mapper/nvidia_fhgbbaae6 mounted as /tmp
/dev/mapper/nvidia_fhgbbaae7 mounted as /home

None of these mappings exist on the root fs.  Also, as you pointed out, the install for some reason decides not to install grub when it deals with a SATA RAID. This seems to be the case whenever it detects one even when it is not the install drive. I did a second install on a different drive as I pointed out. It is a single drive with space partitioned after my Vista partition. Ubuntu still did not install grub on this drive during that install either. The command you suggested:

#dpkg -l grub-pc
  output:

 Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Cfg-files/Unpacked/Failed-cfg/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name            Version         Description
+++-===============-===============-==============================================
un  grub-pc         <none>          (no description available)

I did the install as you suggested. 

aptitude update
aptitude install grub-pc grub-common

this worked.  the /boot/grub directory is now populated, before was empty. It has a grub.cfg I got from http://grub.enbug.org/LVMandRAID modified to look like this:

set timeout=20
set default=0
menuentry "Linux on RAID" {
        insmod dmraid
        set root=(nvidia_fhgbbaae1)
        linux /vmlinuz root=/dev/mapper/nvidia_fhgbbaae1
        initrd /initrd.img
} 
Then I ran:
#grub-install /dev/mapper/nvidia_fhgbbaae1
grub-probe: error: no mapping exists for `nvidia_fhgbbaae1'

This config still does not boot. The kernel cannot find the root fs. during the live cd session I can see dmraid_45 when I do lsmod. As long as this module is loaded, the kernel can see the array and can mount the fs.  I need the help of a grub expert to go further. What is missing?

John

-----Original Message-----

From: Tom H <tomh0665 at gmail.com>

To: ubuntu-users at lists.ubuntu.com

Sent: Mon, Oct 26, 2009 7:33 pm

Subject: Re: boot loader not installed

>> Forgot in my last email:

>> https://wiki.ubuntu.com/Grub2

>> "Recover Grub 2 via LiveCD" is at about 75% down the page.

>> I would "sudo su -" to avoid all the sudos.

>> You will also need to run

>> aptitude update

>> aptitude install grub-pc grub-common

>> after the chroot.

> Those commands don't work from a live cd right? When I tried to install grub

> manually after the install it halted with an error. Basically refused to

> install. I don't think I can install to the installed system from the live

> cd. I it is possible, what would be the necessary steps?

> Your last email also helps. I tried a wubi install around 6 months ago and

> had a heck of a time getting the raid to work then too. Finally found dmraid

> which worked. I didn't remember the name of it so thanks. I assumed that

> since the Ubuntu install found the raid5 and partitioned and installed on it

> that it would take care of all that automatically. 4 sleepless nights later

> it's clear that was a bad assumption.

> Of course it would also be nice it the Install coders did not allow install

> on unsupported drives. Previous versions of Ubuntu never recognized software

> raid configs in the install. When I saw it fully accessible in the

> partitioning phase of the install I got all happy and couldn't resist. Of

> course the standard drive didn't work either.

> Another question: Isn't it possible to put insmod commands after

> root=/dev/xxx? Could I not instruct the kernel to install the dmraid module

> in the boot parameters?

These commands work when booted from a Live CD but only after you

chroot. Once you are chrooted, it will be as if you are booted into

your HD. You could even "su - <yourusername>" and you will have access

to your bash history. So when you run "aptitude update; aptitude

install ..." you will install Grub 2 on your HD.

I do not think that your drive is unsupported. Grub 2 is not installed

if you choose the SATA RAID option; not quite the same thing. I assume

that if you choose "no" to the SATA RAID, Grub 2 is installed.

SATA RAID is set up by the BIOS so you do not need to insmod anything.

-- 

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