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Trouble booting a degraded RAID-1 array
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  1. #1
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    Trouble booting a degraded RAID-1 array

    I should mention that I'm reposting this thread from LinuxQuestions and am hoping a more OS-specific forum will help.

    I've been attempting to migrate my running server to RAID-1 using another hard drive identical to the current one. The general approach I've used is to create new drive to mirror the old one, set up the new drive as a degraded RAID-1 array using mdadm, rsync the contents of the old drive to the new drive, then add the old drive to the new RAID array when everything is working.

    fdisk -l reports
    Code:
    Disk /dev/hda: 251.0 GB, 251000193024 bytes
    255 heads, 63 sectors/track, 30515 cylinders
    Units = cylinders of 16065 * 512 = 8225280 bytes
    
       Device Boot      Start         End      Blocks   Id  System
    /dev/hda1   *           1          13      104391   fd  Linux raid autodetect
    /dev/hda2              14       30515   245007315   8e  Linux LVM
    
    #Disk /dev/hdb: 251.0 GB, 251000193024 bytes
    255 heads, 63 sectors/track, 30515 cylinders
    Units = cylinders of 16065 * 512 = 8225280 bytes
    
       Device Boot      Start         End      Blocks   Id  System
    /dev/hdb1   *           1          13      104391   fd  Linux raid autodetect
    /dev/hdb2              14       30515   245007315   fd  Linux raid autodetect
    The old disk is /dev/hda and as can be seen I've successfully migrated over the boot partition to run on a RAID device /dev/md1 (though I still boot off hda1 instead of md1).

    On /dev/md0 I've created a logical group /dev/lvm-raid with two logical volumes, lvm0 (filesystem) and lvm1 (swap, yeah raid-0 would be better for this).
    Code:
    # lvscan
      ACTIVE            '/dev/VolGroup00/LogVol00' [232.12 GB] inherit
      ACTIVE            '/dev/VolGroup00/LogVol01' [1.50 GB] inherit
      ACTIVE            '/dev/lvm-raid/lvm0' [232.12 GB] inherit
      ACTIVE            '/dev/lvm-raid/lvm1' [1.50 GB] inherit
    # pvdisplay /dev/md0
      --- Physical volume ---
      PV Name               /dev/md0
      VG Name               lvm-raid
      PV Size               233.66 GB / not usable 0
      Allocatable           yes
      PE Size (KByte)       4096
      Total PE              59816
      Free PE               9
      Allocated PE          59807
      PV UUID               9e8Ixn-xC4P-27qH-YrSP-KO8W-lfli-doMB34
    But whenever I try to boot lvm0 using the following lines in grub
    Code:
    title Fedora Core raid (2.6.17-1.2174_FC5)
            root (hd0,0)
            kernel /vmlinuz-2.6.17-1.2174_FC5 ro root=/dev/lvm-raid/lvm0 rhgb quiet
    quiet
            initrd /initrd-2.6.17-1.2174_FC5.img
    I get the following error during boot
    Code:
    Reading all physical volumes. This may take a while...
    Found volume group "VolGroup00" using metadata type lvm2
    2 logical volume(s) in volume group "VolGroup00" now active
    mount: count not find filesystem '/dev/root'
    setuproot: moving /dev failed: No such file or directory
    setuproot: error mounting /proc: No such file or directory
    setuproot: error mounting /sys: No such file or directory
    switchroot: mount failed: No such file or directory
    Kernel panic - not syncing: Attempted to kill init!
    It seems to me that it's not detecting the lvm-raid volume group at startup.

    I've tried rebuilding the boot image with
    Code:
    mkinitrd -v --with=raid1 /boot/initrd-2.6.17-1.2174_FC5.img 2.6.17-1.2174_FC5
    as well as setting /dev/lvm-raid/lvm0 to be / in /ect/fstab but it doesn't seem to make any difference.

    As well when I boot with a rescue CD /dev/lvm-raid doesn't exist though /dev/VolGroup00 does and I can mount /dev/md0

    Does anyone know how I can successfully boot /dev/lvm-raid/lvm0 ?

    thanks

  2. #2
    Ogilthorpe Guest
    Ok, I have the exact same setup and I will share how I fixed the bootup problem and what is my problem now

    to boot, you need to redo your initrd with the following mods :

    open mkinitscript and put the name of your volume group at vgscan="lvm-raid"

    go in /etc/lvm/lvm.conf and look for a line about md device detection and put it to 0

    do a mkinitrd -v -f --preload=dm-mod with=raid1 /boot/initVERSION.img VERSION

    Now, the system should boot correctly

    My problem is that when I boot on the new degraded lvm-raid, when I do a cat /proc/mdstat, there is only md0 available... my md1 is not there (lvm-raid)... I tried to mdadm -A --force /dev/md1 /dev/sdb2 put it won't work, it says that sdb2 doesn't have a superblock even if mdadm --examine /dev/sdb2 tells me that everything is ok.

    If I boot to the old disk, I see md0 and md1.

    Can someone help me here because it's the last step that I need to do before adding the first disk for the raid to sync.

    Thanks

  3. #3
    Ogilthorpe Guest
    ok, just to update you guys on what I have found...

    if I check the syslog, I see that at bootup, mdadm tries to create md1 but fail because on a bd_claim error, meaning that the partition is already mounted...

    I created my initrd with mkinitrd -f -v --preload=raid1 --preload=dm-mod initVERSION VERSION

    my grub is like this

    root (hd0,0)
    kernel /vmlinuz-VERSION ro root=/dev/lvm-raid/root md=1,/dev/sda2,/dev/sdb2 rhgb quiet
    initrd /initrd-VERSION.img

    What am I doing wrong ????????????

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