Re: root (/) on software raid

From: Erik Karlin (e_karlin_at_yahoo.com)
Date: 08/23/05

  • Next message: Philip Radford: "apache 2.0.54 + mod_php" 
    Date: Tue, 23 Aug 2005 14:34:45 -0400
To: debian-user@lists.debian.org

    On Tue, Aug 23, 2005 at 09:42:15AM -0600, Jamin W. Collins wrote:
    > I've managed to enable software raid on one of my systems. Four
    > different arrays built as follows:
    >
    > /dev/md0: (/boot)
    > - /dev/hda1 & /dev/hdc1
    >
    > /dev/md1: (/var/log)
    > - /dev/hda6 & /dev/hdc6
    >
    > /dev/md2: (/)
    > - /dev/hda7 & /dev/hdc7
    >
    > /dev/md3: (/opt/backup)
    > - /dev/hda8 & /dev/hdc8
    >
    > Three of the four come up perfectly after reboot (md0, md1, & md3). The
    > problem is with md2. After every reboot it's degraded with only hdc7 as
    > a member. I can manually re-add hda7 and it syncs without error and
    > works fine until the next reboot. But I'd like to correct this so this
    > isn't necessary.
    >
    > I'm using grub as my boot loader and the following is the entry being
    > loaded on startup:
    >
    > title Debian GNU/Linux, kernel 2.6.11-1-386
    > root (hd0,0)
    > kernel /vmlinuz-2.6.11-1-386 root=/dev/md2 ro
    > initrd /initrd.img-2.6.11-1-386
    > savedefault
    > boot
    >
    > The system is running sarge, with the exception of the kernel. I'd be
    > happy to provide any further information that may be helpful.
    >

    If you check the rootraiddoc.97.html, usually
    /usr/share/doc/mdadm/rootraiddoc.97.html or via
    http://alioth.debian.org/projects/rootraiddoc

    Down around section 8, just before the appendix, there is this little
    blurb:

    When using mdadm, mkinitrd will only detect disks in the array that are
    running at the time of execution. You should not install a new kernel
    while the array is degraded, otherwise, even if you do an mdadm --add,
    the next reboot will still be degraded! The array is started at boot
    time by script. You can see what is in the script of the initrd by
    mounting it, e.g.

    mount /boot/initrd.img-X.X.X /mnt -o loop
    cat /mnt/script

    And look for the array start line similar to

    mdadm -A /devfs/md/0 -R -u 23d8dd00:bc834589:0dab55b1:7bfcc1ec /dev/hda1 /dev/hdc1

    That sounds like what you're seeing 

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