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Old 01-21-2012, 04:55 PM   #1
spyghost
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Registered: Jun 2003
Distribution: Redhat
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Question grub confusion, not automatically loading (always goes back to grub prompt)


hi,

something got screwed up in the server and the OS is noot booting correctly (just goes to grub> prompt).

Every reboot, this needs to be done:
grub> find /grub/stage1
hd(2,0)
hd(3,0)
grub> root(hd2,0)
grub> kernel /vmlinuz-2.6.18-164.el5 ... (truncated)
grub> initrd /initrd-2.6.18-164.el5.img
grub> boot

<OS boot correctly>

From OS, here is what grub.conf looks like:
# cat /boot/grub/grub.conf
title Red Hat Enterprise Linux Server (2.6.18-164.el5PAE)
root (hd0,0)
kernel /vmlinuz-2.6.18-164.el5PAE ... (truncated)
initrd /initrd-2.6.18-164.el5PAE.img
# cat /boot/grub/device.map
(hd0) /dev/sda
(hd1) /dev/sdb

The server has 4 internal disks and the grub installed on the first 2 hard disks (/dev/sda, and /dev/sdb). BIOS boot order is correct in that it boots sda first.

This used to work before, not sure on what has been done here why it doesn't boot automatically. For sure grub is installed in /dev/sda and /dev/sdb (NOT /dev/sdc and /dev/sdd). Tried to dump the first 446 blocks and GRUB was only in sda and sdb, NOT in sdc and sdd.
 
Old 01-22-2012, 06:34 AM   #2
Larry Webb
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I am no expert but seems your hd mapping has changed. Go to Source Forge and download, run and post the results please

Boot Info Script
 
1 members found this post helpful.
Old 01-23-2012, 08:00 PM   #3
spyghost
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Registered: Jun 2003
Distribution: Redhat
Posts: 245

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I didn't run the script, but providing additional info:

/dev/sda (hd0) - installed with GRUB (verified with dd if=/dev/sda bs=446 count=1 | strings)
/dev/sdb (hd1) - mirror of hd0
/dev/sdc (hd2) - just an additional disk (dd of first 446 blocks result in nothing)
/dev/sdd (hd3) - similar to hd3

the server is dell r710 so there is no option in mixing the boot order of the 4 disks. the options are just network, internal disk/s, or optical drive.

the thing that confuses me are these 2 scenarios:
1 - boot up
- only the grub> prompt is shown
- find /grub/stage1 shows hd2,0 and hd3,0
- i always had to type kernel... initrd... boot and OS goes up
2 - while OS is up and running
- find /grub/stage1 shows hd0,0 and hd1,0 - which is correct

the 2 things that i have done were to place each of the 2 sets of hard disks in the menu.lst and run grub-install /dev/sd[ab] then grub> root, setup. All have no effect.

the thing is, it is certain that the boot order goes to /dev/sda (hd0) because i am being prompted with a grub>. if it goes to either sd[cd], then i won't be prompt with grub>, but instead no OS found will be shown, but it doesn't show up.
 
  


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