Grub

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Grub

There may be an occasion when an issue with grub will cause your server to not boot, there is no need to reinstall the system, you just need to repair the installation of grub.

Fix the GRUB from the startup command line

Normally if grub can not start and your system is not damagaed, you will have a basic system prompt ... otherwise go to Chapter 2.

I presume that your SME Server is using a RAID1 of two disks, otherwise you have to adapt this HOWTO to your setup.

In a terminal at the command prompt issue the following commands 

grub
root (hd0,0)
Filesystem type is ext2fs, partition type 0xfd

setup (hd0)

Checking if "/boot/grub/stage1" exists... no
Checking if "/grub/stage1" exists... yes
Checking if "/grub/stage2" exists... yes
Checking if "/grub/e2fs_stage1_5" exists... yes
Running "embed /grub/e2fs_stage1_5 d (hd0)"... 16 sectors embedded
succeeded
Running "install /grub/stage1 (hd0) (hd0)1+16 p (hd0,0)/grub/stage2 /grub/grub.conf"...
succeeded
Done.

reboot

to /dev/sdb you issue the following commands, using one of the following disk labels (sdc, sdd, sde ....) 

grub
root (hd1,0)
setup (hd1)

grub must be installed on all other drives to give the capacity to operate the system. To reach the boot menu of the bios, will depend on your hardware ... F12 under dell, Acer Esc, F11 from msi .... my sme is with Raid1 so I have two drives, you will need to adapt my example to your the number of disks.

Fix the GRUB with the official SME Server CDROM

I presume that your SME Server is on a RAID1 of two disks (sda, sdb), otherwise you will have to adapt this HOWTO.

  • start the system with your official SME Server CDROM
  • give at prompt : linux rescue
  • set your language and your keyboard
  • set to no the start of network interfaces
  • set to continue the question about how the system is mounted in /mnt/sysimage
  • set to ok
  • give at prompt :
chroot /mnt/sysimage
su -
  • then you can perform
grub-install /dev/sda
grub-install /dev/sdb

do it for each disk you have on your server

  • to exit
exit
exit
halt

then you can test if the grub is present on your drives.


Fix the GRUB with the systemrescuecd

Important.png Note:
We go to work with SystemRescueCd which is a Linux system rescue disk available as a bootable CD-ROM or USB stick for administrating or repairing your system and data after a crash.Download. The goal is to mount your logical volumes on /mnt where you can save them on a usb disk.


I presume that your SME Server is on a RAID1 of two disks, otherwise you will have to adapt this HOWTO.

  • start the system with your system rescue cd or you usb stick, choose your keyboard settings
  • then start the server X
startx
  • open a terminal to verify if your raid is initiated.
cat  /proc/mdstat
  • if you are lucky the output will look like this
# cat /proc/mdstat 
Personalities : [raid1] 
md99 : active raid1 sdb1[1] sda1[0]
      104320 blocks [2/2] [UU]
      
md100 : active raid1 sdb2[1] sda2[0]
      262036096 blocks [2/2] [UU]
      
unused devices: <none>
  • so we need to launch the LVM
vgchange -ay
  • afterward if the LVM is launched without error messages, we can mount the LVM in /mnt


Information.png Tip:
if you have a logical volume that is not named /dev/main/root, you can type the following command to list all your logical volumes, and then adapt this to your configuration. 


lvdisplay
  • Now you have successfully mounted your LVM do the following
mkdir /mnt/sysimage
mount /dev/main/root /mnt/sysimage
mount -o bind /dev /mnt/sysimage/dev
mount -o bind /proc /mnt/sysimage/proc
chroot /mnt/sysimage /bin/bash
  • We will have to mount the /boot of your system, which is normally contained in / dev/md1.

To do this you must send a 

cat /proc/mdstat
  • note the md(X) the smallest (about 100 megs) then in your root terminal do this:
mount /dev/md(X) /boot

and then 

grub
root (hd0,0)
setup (hd0)

you can restart and continue the tutorial

Installation of grub on other disks

  • once your Sme started, you need to login in as root

then type 

grub

device (hd0) /dev/sda
root (hd0,0)
setup (hd0)
device (hd1) /dev/sdb
root (hd1,0)
setup (hd1)
quit
  • same for other drives, you implement one each time. My SME Server is with Raid1 so I have two drives, you will need to adapt my example to your the number of disks.

from there you can reboot your server and check that the grub is installed on each hd. it is simple, with the boot menu or bios, you say on what hd you want to boot . to reach the boot menu of the bios, well it depends on your hardware ... F12 under dell, Acer Esc, F11 from msi ....

Installation of grub on a new disk

When your system is started you can install grub by the command Line on any other disk you want. You have to change by the name of your new disk. 

[root@sme8dev64 ~]# grub
Probing devices to guess BIOS drives. This may take a long time.


    GNU GRUB  version 0.97  (640K lower / 3072K upper memory)

[ Minimal BASH-like line editing is supported.  For the first word, TAB
  lists possible command completions.  Anywhere else TAB lists the possible
  completions of a device/filename.]

grub> device (hd0) /dev/sdb
device (hd0) /dev/sdb

grub> root (hd0,0)
root (hd0,0)
Filesystem type is ext2fs, partition type 0xfd

grub> setup (hd0)
setup (hd0)
Checking if "/boot/grub/stage1" exists... no
Checking if "/grub/stage1" exists... yes
Checking if "/grub/stage2" exists... yes
Checking if "/grub/e2fs_stage1_5" exists... yes
Running "embed /grub/e2fs_stage1_5 (hd1)"...  15 sectors are embedded.
succeeded
Running "install /grub/stage1 (hd0) (hd0)1+15 p (hd1,0)/grub/stage2 /grub/grub.conf"... succeeded

Done. 

grub> quit
quit

Fix Grub on a HP Proliant DL380 G2

see bugzilla:7024 for more information The server is configured using the Hardware RAID in RAID5, 6 drives as 1 logical drive (1 spare).

The forum posts describing the issues is here:

The solution posted by CharlieBrady on the forums can be found here: 

System information:
HP Proliant DL380 G2
Dual P3 1.266GHz (original system processors)
Memory: 2GB RAM 
Hard Drives: 6x 36.4GB
Compaq Hot-swappable 36.4GB, 10k or 15k RPM (mixed set) (BF03664664)

To re-configure GRUB, follow these steps

1. Rename /etc/grub.conf to /etc/grub.old 

cp /etc/grub.conf /etc/grub.old

2. edit /etc/grub.conf 

nano etc/grub.conf

3. uncomment the line that starts with #boot=

4. edit the boot= line to read 

boot=/dev/cciss/c0d0

This line previously read (if i remember correctly) #boot=/dev/md0

5. open /boot/grub/device.map 

nano /boot/grub/device.map

5a. You SHOULD read 

(hd0)     /dev/cciss/c0d0

6. Ran GRUB with the following parameters: 

/sbin/grub --batch --device-map=/boot/grub/device.map --config-file=/boot/grub/grub.conf --no-floppy

7. Ran the following commands in grub 

grub> root (hd0,0)
grub> setup (hd0)
grub> quit

8. Restarted the server

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