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I have a remote CentOS 6.4 server (with KVM access), when I received the server it was running with LVM on single disk (sda)

I managed to remove LVM and install raid 1 in sda and sdb disks

the mirroring is working fine, my only issue now is that every time I reboot the server I got the grub command line and I have manually boot using command

grub> configfile (hd1,0)/grub/grub.conf

OR

grub> configfile (hd0,0)/grub/grub.conf

then it will boot fine without any error.

Any idea how can I make it auto boot ?

Note: each disk (sda & sdb) is 2TB size, could this be the problem?

my settings

Filesystem            Size  Used Avail Use% Mounted on
/dev/md2              1.8T  1.1G  1.7T   1% /
tmpfs                  16G     0   16G   0% /dev/shm
/dev/md0              1.9G   69M  1.8G   4% /boot


 # cat /proc/mdstat 

 Personalities : [raid1] 
 md2 : active raid1 sda3[2] sdb3[0]
        1940882240 blocks super 1.2 [2/2] [UU]

 md1 : active raid1 sdb2[0] sda2[2]
       10482176 blocks super 1.2 [2/2] [UU]

 md0 : active raid1 sdb1[0] sda1[1]
       2008000 blocks [2/2] [UU]

  unused devices: <none>

# fdisk -l /dev/sda

Disk /dev/sda: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 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: 0x000b0530

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1         250     2008093+  83  Linux
/dev/sda2             251        1556    10490445   82  Linux swap / Solaris
/dev/sda3            1557      243201  1941013462+  fd  Linux raid autodetect


# fdisk -l /dev/sdb

Disk /dev/sdb: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 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: 0xadb3bd62

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1         250     2008093+  fd  Linux raid autodetect
/dev/sdb2             251        1556    10490445   82  Linux swap / Solaris
/dev/sdb3            1557      243201  1941013462+  fd  Linux raid autodetect

# cat 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_srv6953-lv_root
#          initrd /initrd-[generic-]version.img
#boot=/dev/sda
default=0
timeout=5
splashimage=(hd1,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS (2.6.32-358.18.1.el6.x86_64)
    root (hd1,0)
    kernel /vmlinuz-2.6.32-358.18.1.el6.x86_64 ro root=/dev/md2 KEYBOARDTYPE=pc KEYTABLE=us LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 crashkernel=auto rhgb quiet rd_retry=20
    initrd /initramfs-2.6.32-358.18.1.el6.x86_64.img
title CentOS (2.6.32-358.el6.x86_64)
    root (hd1,0)
    kernel /vmlinuz-2.6.32-358.el6.x86_64 ro root=/dev/md2  KEYBOARDTYPE=pc KEYTABLE=us LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 crashkernel=auto rhgb quiet
    initrd /initramfs-2.6.32-358.el6.x86_64.img



# 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> root (hd0,0)
root (hd0,0)
 Filesystem type is ext2fs, partition type 0xfd
grub> setup (hd0)
setup (hd0)
 Checking if "/boot/grub/stage1" exists... yes
 Checking if "/boot/grub/stage2" exists... yes
 Checking if "/boot/grub/e2fs_stage1_5" exists... yes
 Running "embed /boot/grub/e2fs_stage1_5 (hd0)"...  27 sectors are embedded.
succeeded
 Running "install /boot/grub/stage1 (hd0) (hd0)1+27 p (hd0,0)/boot/grub/stage2 /boot/grub/grub.conf"... succeeded
Done.
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2 Answers 2

You need to re-install grub on the server hard disk device. To know the device address, type in a terminal

  sudo fdisk -l

This will list the disks and their volumes in a list. Note the device where you need to install the grub. The size of thee device shall give you a hint. If /dev/sda is the device where grub needs to be installed, go to terminal and type

 sudo grub-install /dev/sda

Reboot your server and check if the problem is resolved.

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I already did that, same thing :( –  AFT Sep 15 '13 at 18:15
    
I found the solution, I had to use dd (after removing the disk from raid) to clean the disk and readd it, I will post the steps that I did after 8 hours (serverfault.com is asking me to wait 8 hours :( ) –  AFT Sep 15 '13 at 18:22
up vote 0 down vote accepted

OK

I did the following:

  1. Remove sda from raid (using mdadm)
  2. Run dd (dd if=/dev/zero of=/dev/sda bs=512 count=1000)
  3. Copy the current disk partition table (sfdisk -d /dev/sdb | sfdisk /dev/sda)
  4. add disk to raid (using mdadm)
  5. reinstall grub (using grub command)
  6. run grub-install /dev/sda
  7. Reboot

and now it's working :)

I did all the above steps before except step 2, it seems I need to clear the disk with dd

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