Dual boot install - ubuntu studio 9.04 - GRUB error 21

illnamiqui · 08-11-2009, 07:14 AM

Hi everyone,

I am new tu Linux and this is my first install.

I wanted to install Ubuntu Studio 9.04 in a Dell precision 670 Workstation. I have Windowx xp installed so I wanted to have both.

During the installation everything seemed fine, but when rebooted i get the error:
GRUB Loading stage1.5

GRUB Loading, please wait...
Error 21

I have 2 hard drives in a RAID array
CERC 2s#0-#0 ARRAY0

During the installation it asks if i want to activate Serial ATA Raid devices, i chose: yes

The partitions look like this:

/dev/sda1
/dev/sda2
/dev/sdc1
/dev/sdc2
/dev/sdc5 (root file system)
/dev/sdc6 (SWAP)

I have tried entering in rescue mode and reinstall GRUB boot loader
but then i don't know which option i should use
(hd0) - /dev/hda
(hd0,1) - /dev/hda2
(hd2,4) - /dev/sdc5
(fd0) - /dev/fd0

I have searched for the GRUB 21 error, and read about changing something in the bios or something like that but i have no idea what to do...
Can anyone guide me please?

Thanks for your time!

yancek · 08-12-2009, 08:35 PM

Grub Error 21: Selected disk does not exist
This error is returned if the device part of a device- or full file name refers to a disk or BIOS device that is not present or not recognized by the BIOS in the system.

If your root filesystem for UBuntu is indeed on sdc5, issuing the following commands from a command line from your Ubuntu Installation CD:

sudo grub
root (hd2,4)
setup (hd0)
quit

What happened to sdb? Did you have another dirve attached during the install? The error above indicates Grub is looking for its boot files on a disk no longer attached, or at least not correctly named in menu.lst file. I don't use RAID so I don't know what impact that might have.

sysfce2 · 08-13-2009, 11:40 PM

How bad do you want to keep your RAID array?
I believe it is possible to install on a RAID array, but it is much more difficult.
I tried for a couple of days and couldn't get it to work (keep in mind I am a Linux newbie), so I destroyed the RAID array and reinstalled Windows and Linux on separate hard drives. It was relatively easy at that point.

EDIT: Installing Linux on RAID is one thing - no problem. Using the RAID drive to boot from is where I ran into problems - a possible solution is to use a non-RAID device to boot (or maybe the windows boot manager).