[SOLVED] Issue with two hard-drives, CentOS 6 and Ubuntu on each

General support questions

[SOLVED] Issue with two hard-drives, CentOS 6 and Ubuntu on each

Postby vrkrao » 2011/09/10 18:05:56

Hi,

This probably has nothing to do with CentOS as such, could be a general problem. Need help.

I had CentOS 6 running fine until I decided to procure a second hard disk and loaded Ubuntu 11.04 on it.
I use CentOS 6 for work. I wanted a more user-friendly (in terms of tools and apps available) for home use.
Hence, loaded Ubuntu 11.04 on a second hard disk. The idea was to specify the Hard-disk to boot from, at the time of booting.

The background:
* Motherboard + Processor = Intel DH67BL + i-5
* The Machine had CentOS 6 fully working with Hard-drive 1 - Western Digital 1TB, Sata3, CentOS 6, sitting on SATA port 0 (This Mobo has 2 SATA, 2 eSATA, 2 SATA3 ports)
* Hard-drive 2 - Seagate 500GB, Sata with Ubuntu 11.04, SATA port 3
While installing Ubuntu, it asked me where to install showing both the hard disks. I installed on the new one (500GB). Installation went fine and working
fine.
* Both drives are recognized by BIOS

The problem:
* On boot, i get two options on boot screen (F2 - Bios setup) and (F10 - Boot menu)
* I press F10, I see both hard-disks
* Irrespective of my selection, It's always booting Ubuntu from hard disk 2.
* I unplugged the hard disk with Ubuntu, the system still tries to boot from Ubuntu disk, It's coming to some grub prompt (have to
repeat the exercise to precisely report that, but don't mind doing it if necessary). Says something like, didn't find anything to load.
* I connected the hard disk with Ubuntu back, again, it boots in Ubuntu only.
* I'm not able to boot CentOS 6 at all.

Please help.

regds.,
Ramki.
vrkrao
 
Posts: 34
Joined: 2011/07/28 16:07:31

Re: Issue with two hard-drives, CentOS 6 and Ubuntu on each

Postby atemp » 2011/09/10 19:22:59

What happened? You have replaced the startup code of your CentOS bootloader, which was on the MBR of the first disc, with those from Ubuntu.

A possible solution could be:
Boot into CentOS with e.g. a DVD in rescue mode and there reinstall GRUB. But instead of using again the MBR - which would overwrite the Ubuntu-GRUB - use the partition your /boot dir is on. Once this is done you can use the ubuntu grub to chainload the CentOS-GRUB.
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Re: Issue with two hard-drives, CentOS 6 and Ubuntu on each

Postby TrevorH » 2011/09/10 19:36:43

Or add the CentOS disk to the Ubuntu grub menu.
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TrevorH
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Re: Issue with two hard-drives, CentOS 6 and Ubuntu on each

Postby vrkrao » 2011/09/10 19:43:30

atemp wrote:
What happened? You have replaced the startup code of your CentOS bootloader, which was on the MBR of the first disc, with those from Ubuntu.

A possible solution could be:
Boot into CentOS with e.g. a DVD in rescue mode and there reinstall GRUB. But instead of using again the MBR - which would overwrite the Ubuntu-GRUB - use the partition your /boot dir is on. Once this is done you can use the ubuntu grub to chainload the CentOS-GRUB.


Partly understood your suggestion.

The machine had CentoOS 6 running fine for a month now.
I bought second hard disk and loaded ubuntu on it. During installation, it asked me for the hard-disk to be installed.
I gave the new disk as the option. It had installed on second disk.

Would this replace the startup code of CentOS bootloader sitting on disk 1 ??
Wouldn't there be two MBRs one on each disk??
How do i reinstall the GRUB?? Please elaborate your last sentence.

regds.,
Ramki.
vrkrao
 
Posts: 34
Joined: 2011/07/28 16:07:31

Re: Issue with two hard-drives, CentOS 6 and Ubuntu on each

Postby vrkrao » 2011/09/10 19:49:46

TrevorH wrote:
Or add the CentOS disk to the Ubuntu grub menu.


I'll work on that.

regds.,
Ramki.
vrkrao
 
Posts: 34
Joined: 2011/07/28 16:07:31

Re: Issue with two hard-drives, CentOS 6 and Ubuntu on each

Postby atemp » 2011/09/11 06:28:30

TrevorH wrote:
Or add the CentOS disk to the Ubuntu grub menu.


There are two ways of doing this, by chainloading another GRUB as i suggested already or by booting the kernel directly from the ubuntu GRUB. That would be a bad idea since it would start to fail as soon as the kernel is removed by CentOS due to updates.

vrkrao wrote:
Would this replace the startup code of CentOS bootloader sitting on disk 1 ??
Wouldn't there be two MBRs one on each disk??
How do i reinstall the GRUB?? Please elaborate your last sentence.


You installed ubuntu on the second disc but by selecting GRUB on MBR you probably wrote it to the MBR of the first disc. You should have chosen partition instead of MBR, if ubuntu allows that. Anyway, too late now.

Reinstalling GRUB is no big magic, just take a look here: http://www.centos.org/docs/5/html/Insta ... -boot.html

The docu is from CentOS 5, but its quite similar. When in rescue mode follow section 26.2.1. You have to exchange /dev/hda with the device name that your /boot is on, use "fdisk -l" to find out what devices you have. Look into /etc/fstab of your CentOS system. Hope that helps.
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Re: Issue with two hard-drives, CentOS 6 and Ubuntu on each

Postby vrkrao » 2011/09/11 12:15:46

@atemp

I have done that. Still remains same. The boot loader is sitting on my centOS disk as you suspect, I think. I have done sudo fdisk -l on ubuntu. Here's how it looks.


Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000763f1

Device Boot Start End Blocks Id System
/dev/sda1 * 1 64 512000 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 64 121602 976248832 8e Linux LVM

Disk /dev/sdb: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000c0245

Device Boot Start End Blocks Id System
/dev/sdb1 1 59760 480017408 83 Linux
/dev/sdb2 59760 60802 8366081 5 Extended
/dev/sdb5 59760 60802 8366080 82 Linux swap / Solaris

To implement Trevor's Idea, CentOS follows grub where as Ubuntu follows grub2. So, it doesn't look straight forward.

More suggestions for me??

regds.,
Ramki.
vrkrao
 
Posts: 34
Joined: 2011/07/28 16:07:31

Re: Issue with two hard-drives, CentOS 6 and Ubuntu on each

Postby vrkrao » 2011/09/12 07:43:30

Hi Atemp, Trevor,

Following these two threads.
http://ubuntuforums.org/showthread.php?t=1476603
https://help.ubuntu.com/community/Grub2


Was able to add the CentOS menu to Ubuntu grub.
But, looks like i'm not able to link the linux, initrd execs correctly.

Ubuntu uses Grub2 whereas CentOS uses grub. Have used the script
as sourceforge.net to get the following bootinfo on the disks. The results are as follows.
(Cut - Paste of result file)


Boot Info Script 0.60 from 17 May 2011


============================= Boot Info Summary: ===============================

=> Grub2 (v1.99) is installed in the MBR of /dev/sda and looks at sector 1 of
the same hard drive for core.img. core.img is at this location and uses an
embedded config file:

---------------------------------------------------------------------------
search.fs_uuid fa89048e-f583-4626-add3-4f78265bcac7 root
set
prefix=($root)/boot/grub---------------------------------------------------
-----------------------------.
=> No boot loader is installed in the MBR of /dev/sdb.

sda1: __________________________________________________________________________

File system: ext4
Boot sector type: Grub Legacy
Boot sector info: Grub Legacy (v0.97) is installed in the boot sector
of sda1 and looks at sector 543186 of the same hard
drive for the stage2 file. A stage2 file is at this
location on /dev/sda. Stage2 looks on partition #1
for /grub/grub.conf.
Operating System:
Boot files: /grub/menu.lst /grub/grub.conf

sda2: __________________________________________________________________________

File system: LVM2_member
Boot sector type: -
Boot sector info:

sdb1: __________________________________________________________________________

File system: ext4
Boot sector type: -
Boot sector info:
Operating System: Ubuntu 11.04
Boot files: /boot/grub/grub.cfg /etc/fstab /boot/grub/core.img

sdb2: __________________________________________________________________________

File system: Extended Partition
Boot sector type: -
Boot sector info:

sdb5: __________________________________________________________________________

File system: swap
Boot sector type: -
Boot sector info:

============================ Drive/Partition Info: =============================

Drive: sda _____________________________________________________________________

Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes

Partition Boot Start Sector End Sector # of Sectors Id System

/dev/sda1 * 2,048 1,026,047 1,024,000 83 Linux
/dev/sda2 1,026,048 1,953,523,711 1,952,497,664 8e Linux LVM


Drive: sdb _____________________________________________________________________

Disk /dev/sdb: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes

Partition Boot Start Sector End Sector # of Sectors Id System

/dev/sdb1 2,048 960,036,863 960,034,816 83 Linux
/dev/sdb2 960,038,910 976,771,071 16,732,162 5 Extended
/dev/sdb5 960,038,912 976,771,071 16,732,160 82 Linux swap / Solaris


"blkid" output: ________________________________________________________________

Device UUID TYPE LABEL

/dev/sda1 2df7c975-c906-4105-981a-3a623b978202 ext4
/dev/sda2 ocY2Gf-ZdPu-4OH7-yZxD-m3eC-MNFL-lXUjNA LVM2_member
/dev/sdb1 fa89048e-f583-4626-add3-4f78265bcac7 ext4
/dev/sdb5 ade4674d-b6ab-44e2-b38e-345cceb231cf swap

================================ Mount points: =================================

Device Mount_Point Type Options

/dev/sdb1 / ext4 (rw,errors=remount-ro,commit=0)
/dev/sr0 /media/CentOS_6.0_Final iso9660 (ro,nosuid,nodev,uhelper=udisks,uid=1000,gid=1000,iocharset=utf8,mode=0400,dmode=0500)


============================= sda1/grub/grub.conf: =============================

--------------------------------------------------------------------------------
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,0)
# kernel /vmlinuz-version ro root=/dev/mapper/vg_prabha-lv_root
# initrd /initrd-[generic-]version.img
boot=/dev/sda
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS Linux (2.6.32-71.29.1.el6.x86_64)
root (hd0,0)
kernel /vmlinuz-2.6.32-71.29.1.el6.x86_64 ro root=/dev/mapper/vg_prabha-lv_root rd_LVM_LV=vg_prabha/lv_root rd_LVM_LV=vg_prabha/lv_swap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=us crashkernel=128M rhgb quiet
initrd /initramfs-2.6.32-71.29.1.el6.x86_64.img
title CentOS (2.6.32-71.el6.x86_64)
root (hd0,0)
kernel /vmlinuz-2.6.32-71.el6.x86_64 ro root=/dev/mapper/vg_prabha-lv_root rd_LVM_LV=vg_prabha/lv_root rd_LVM_LV=vg_prabha/lv_swap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=us crashkernel=128M rhgb quiet
initrd /initramfs-2.6.32-71.el6.x86_64.img
--------------------------------------------------------------------------------

=================== sda1: Location of files loaded by Grub: ====================

GiB - GB File Fragment(s)

0.260256767 = 0.279448576 grub/grub.conf 1
0.260256767 = 0.279448576 grub/menu.lst 1
0.259117126 = 0.278224896 grub/stage2 1
0.062965393 = 0.067608576 initramfs-2.6.32-71.29.1.el6.x86_64.img 2
0.031665802 = 0.034000896 initramfs-2.6.32-71.el6.x86_64.img 2
0.054862976 = 0.058908672 initrd-2.6.32-71.29.1.el6.x86_64kdump.img 1
0.035314560 = 0.037918720 initrd-2.6.32-71.el6.x86_64kdump.img 2
0.043575287 = 0.046788608 vmlinuz-2.6.32-71.29.1.el6.x86_64 2
0.016227722 = 0.017424384 vmlinuz-2.6.32-71.el6.x86_64 1

=========================== sdb1/boot/grub/grub.cfg: ===========================

--------------------------------------------------------------------------------
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
set have_grubenv=true
load_env
fi
set default="0"
if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi

function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}

function recordfail {
set recordfail=1
if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}

function load_video {
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
}

insmod part_msdos
insmod ext2
set root='(/dev/sdb,msdos1)'
search --no-floppy --fs-uuid --set=root fa89048e-f583-4626-add3-4f78265bcac7
if loadfont /usr/share/grub/unicode.pf2 ; then
set gfxmode=auto
load_video
insmod gfxterm
fi
terminal_output gfxterm
insmod part_msdos
insmod ext2
set root='(/dev/sdb,msdos1)'
search --no-floppy --fs-uuid --set=root fa89048e-f583-4626-add3-4f78265bcac7
set locale_dir=($root)/boot/grub/locale
set lang=en_US
insmod gettext
if [ "${recordfail}" = 1 ]; then
set timeout=-1
else
set timeout=50
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/light-gray
if background_color 44,0,30; then
clear
fi
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/10_linux ###
if [ ${recordfail} != 1 ]; then
if [ -e ${prefix}/gfxblacklist.txt ]; then
if hwmatch ${prefix}/gfxblacklist.txt 3; then
if [ ${match} = 0 ]; then
set linux_gfx_mode=keep
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=keep
fi
else
set linux_gfx_mode=text
fi
export linux_gfx_mode
if [ "$linux_gfx_mode" != "text" ]; then load_video; fi
menuentry 'Ubuntu, with Linux 2.6.38-11-generic-pae' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
set gfxpayload=$linux_gfx_mode
insmod part_msdos
insmod ext2
set root='(/dev/sdb,msdos1)'
search --no-floppy --fs-uuid --set=root fa89048e-f583-4626-add3-4f78265bcac7
linux /boot/vmlinuz-2.6.38-11-generic-pae root=UUID=fa89048e-f583-4626-add3-4f78265bcac7 ro quiet splash vt.handoff=7
initrd /boot/initrd.img-2.6.38-11-generic-pae
}
menuentry 'Ubuntu, with Linux 2.6.38-11-generic-pae (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
set gfxpayload=$linux_gfx_mode
insmod part_msdos
insmod ext2
set root='(/dev/sdb,msdos1)'
search --no-floppy --fs-uuid --set=root fa89048e-f583-4626-add3-4f78265bcac7
echo 'Loading Linux 2.6.38-11-generic-pae ...'
linux /boot/vmlinuz-2.6.38-11-generic-pae root=UUID=fa89048e-f583-4626-add3-4f78265bcac7 ro single
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-2.6.38-11-generic-pae
}
### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/20_memtest86+ ###
menuentry "Memory test (memtest86+)" {
insmod part_msdos
insmod ext2
set root='(/dev/sdb,msdos1)'
search --no-floppy --fs-uuid --set=root fa89048e-f583-4626-add3-4f78265bcac7
linux16 /boot/memtest86+.bin
}
menuentry "Memory test (memtest86+, serial console 115200)" {
insmod part_msdos
insmod ext2
set root='(/dev/sdb,msdos1)'
search --no-floppy --fs-uuid --set=root fa89048e-f583-4626-add3-4f78265bcac7
linux16 /boot/memtest86+.bin console=ttyS0,115200n8
}
### END /etc/grub.d/20_memtest86+ ###

### BEGIN /etc/grub.d/30_os-prober ###
if [ "x${timeout}" != "x-1" ]; then
if keystatus; then
if keystatus --shift; then
set timeout=-1
else
set timeout=0
fi
else
if sleep --interruptible 3 ; then
set timeout=0
fi
fi
fi
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###

### BEGIN /etc/grub.d/41_custom ###
if [ -f $prefix/custom.cfg ]; then
source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###
--------------------------------------------------------------------------------

=============================== sdb1/etc/fstab: ================================

--------------------------------------------------------------------------------
# /etc/fstab: static file system information.
#
# Use 'blkid -o value -s UUID' to print the universally unique identifier
# for a device; this may be used with UUID= as a more robust way to name
# devices that works even if disks are added and removed. See fstab(5).
#
#
proc /proc proc nodev,noexec,nosuid 0 0
# / was on /dev/sdb1 during installation
UUID=fa89048e-f583-4626-add3-4f78265bcac7 / ext4 errors=remount-ro 0 1
# swap was on /dev/sdb5 during installation
UUID=ade4674d-b6ab-44e2-b38e-345cceb231cf none swap sw 0 0
--------------------------------------------------------------------------------

=================== sdb1: Location of files loaded by Grub: ====================

GiB - GB File Fragment(s)

248.135002136 = 266.432929792 boot/grub/core.img 1
248.139904022 = 266.438193152 boot/grub/grub.cfg 1
1.133983612 = 1.217605632 boot/initrd.img-2.6.38-11-generic-pae 2
0.892032623 = 0.957812736 boot/vmlinuz-2.6.38-11-generic-pae 1
1.133983612 = 1.217605632 initrd.img 2
0.892032623 = 0.957812736 vmlinuz 1

=============================== StdErr Messages: ===============================

unlzma: Decoder error
##############

I see /dev/sda1 mounted in ubuntu as /media/UUID (the big hex number).

This is what, I have written in 40_custom the custom menu file of Ubuntu to list CentOS.
-----
menuentry "CentOS Linux (2.6.32-71.29.1.el6.x86_64)" {
insmod ext4
#set root='(hd0,1)'
set root= '(/dev/sda,1)'
search --no-floppy --fs-uuid --set=root 2df7c975-c906-4105-981a-3a623b978202
linux /vmlinuz-2.6.32-71.29.1.el6.x86_64 root=UUID=2df7c975-c906-4105-981a-3a623b978202
initrd /initramfs-2.6.32-71.29.1.el6.x86_64.img
-------
This shows up in grub.cfg (equivalent to grub.conf) when i update the grub. Also shows up in boot
menu. But, unable to link the linux image of centOS.


Any help appreciated.

regds.,
Ramki.
vrkrao
 
Posts: 34
Joined: 2011/07/28 16:07:31

Re: Issue with two hard-drives, CentOS 6 and Ubuntu on each

Postby atemp » 2011/09/12 08:04:03

vrkrao wrote:
I have done that. Still remains same.


The log of your last post looks actually good.

Tell us what happens if you chainload the grub on sda1 from the grub on sda.
In the GRUB console type something like
root (hd0,0)
chainloader +1
boot
atemp
 
Posts: 29
Joined: 2011/09/06 11:51:13

Re: Issue with two hard-drives, CentOS 6 and Ubuntu on each

Postby vrkrao » 2011/09/12 08:56:06

Hi Atemp,

Thanks for your reply.
It goes to grub_rescue prompt only if i remove the second HD and try to boot.
--------
In the current scenario, when i successfully created the menu in ubuntu, I enter the ubuntu boot menu
while booting and select CentOS. Then I see the following.

------
error: file not found
error: no argument specified
press any key to continue
---------
then it continues, Then I see this:

-----
can't mount root file system
mount: /dv/sda1 already mounted or /sysroot busy
mount: according to mtab, /dev/da1 is already mounted on /sysroot
____
Last two (mount:....) lines repeatedly printed for about 10-15 times and then I see this

----
can't mount root file system
boot failed, sleeping forever
----
Then it tries to recognise mouse, keyboard (text lines) and the same thing repeats.

__________________________________________________________________________

I have a different question,

1. I don't mind re-installng Ubuntu. I have data on HD1 and CentOS. hence, it is important.
HD2 is brand new. I can do this if you say we can get into CentOS by doing this.

2. Once, we get into CentOS, can I remove the HD1, connect only HD2 and reload ubuntu.
I'll choose from BIOS, which hard disk to boot. I started with this idea. The mistake i did
is to have HD1 left connected.

Please see how to recover CentOS. Can we re-write MBR of HD1??? etc etc.

regds.,
Ramki.
vrkrao
 
Posts: 34
Joined: 2011/07/28 16:07:31

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