md0 error

[Jiri Mothejzik]

Hello, grub2 asked me to send this bugreport, so I will. :)

# grub-install /dev/sdb
/usr/sbin/grub-probe: error: no such disk.
Auto-detection of a filesystem of /dev/md0 failed.
Please report this together with the output of "/usr/sbin/grub-probe
--device-map=/boot/grub/device.map --target=fs -v /boot/grub" to
<address@hidden>

# /usr/sbin/grub-probe --device-map=/boot/grub/device.map --target=fs -v
/boot/grub
/usr/sbin/grub-probe: info: the size of hd0 is 1953525168.
/usr/sbin/grub-probe: info: the size of hd0 is 1953525168.
/usr/sbin/grub-probe: info: the size of hd0 is 1953525168.
/usr/sbin/grub-probe: info: the size of hd0 is 1953525168.
/usr/sbin/grub-probe: info: the size of hd0 is 1953525168.
/usr/sbin/grub-probe: info: the size of hd0 is 1953525168.
/usr/sbin/grub-probe: info: the size of hd0 is 1953525168.
/usr/sbin/grub-probe: info: the size of hd0 is 1953525168.
/usr/sbin/grub-probe: info: the size of hd0 is 1953525168.
/usr/sbin/grub-probe: info: the size of hd0 is 1953525168.
/usr/sbin/grub-probe: info: changing current directory to /dev.
/usr/sbin/grub-probe: info: changing current directory to dri.
/usr/sbin/grub-probe: info: changing current directory to snd.
/usr/sbin/grub-probe: info: changing current directory to net.
/usr/sbin/grub-probe: info: changing current directory to shm.
/usr/sbin/grub-probe: info: changing current directory to mapper.
/usr/sbin/grub-probe: info: opening md0.
/usr/sbin/grub-probe: error: no such disk.


What I am trying to do is to have software RAID1 on partition / (md0)
and /var (md1).
I have two disks - /dev/sda and /dev/sdb.
I would like to have / on sw raid to have the system ready and prepared
in case of sda crash.
So I tried to initialize boot sector even on sdb, therefore this attempt.

Actually, md0 and md1 are degraded raids only on sdb, while the system
was originally installed only on sda.
So still, grub boots from sda, but the data are already used from sw
raid md0, md1 (and physically sdb).

System: debian squeeze

Following, you will find some more information that might be useful.

# uname -a
Linux saturn 2.6.32-5-686-bigmem #1 SMP Fri Dec 10 16:59:53 UTC 2010
i686 GNU/Linux

# cat /etc/fstab
proc            /proc           proc    defaults        0       0
/dev/md0        /       ext3    errors=remount-ro       0       1
/dev/md1        /var    ext3    defaults        0       2

# mount
/dev/md0 on / type ext3 (rw,errors=remount-ro)
tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
udev on /dev type tmpfs (rw,mode=0755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620)
/dev/md1 on /var type ext3 (rw)

# grub-probe -t fs_uuid /dev/md0
grub-probe: error: cannot find a device for /dev/md0 (is /dev mounted?).

# grub-probe -t fs_uuid /dev/sda1
grub-probe: error: cannot find a device for /dev/sda1 (is /dev mounted?).

# blkid
/dev/sda1: LABEL="/" UUID="4e7e0377-e748-438b-b99c-4119cce989a6"
TYPE="ext3" SEC_TYPE="ext2"
/dev/sda2: LABEL="/var" UUID="b7ac39f0-0a9c-495b-8249-8ec548cb0a43"
TYPE="ext3" SEC_TYPE="ext2"
/dev/sda3: UUID="c6f734bc-424c-4880-99c5-fd597276c3fe" TYPE="swap"
/dev/sdb1: UUID="9de4311f-f682-b07c-8524-84a6e390a598"
TYPE="linux_raid_member"
/dev/sdb2: UUID="cf4ac51d-e8a9-43eb-8524-84a6e390a598"
TYPE="linux_raid_member"
/dev/md1: UUID="0ea7e641-3203-4ab3-b5bf-030320295dfb" TYPE="ext3"
/dev/md0: UUID="76bfc41b-14e7-4e30-8da1-901b14323a1a" TYPE="ext3"

As grub failed to detect my sw raid, manually edited grub.cfg (actually
booted item) is:
menuentry 'Debian GNU/Linux, with Linux 2.6.32-5-686-bigmem RAID'
--class debian --class gnu-linux --class gnu --class os {
        insmod raid
        insmod mdraid
        insmod ext2
        insmod part_msdos
        set root='(md0,msdos1)'
        search --no-floppy --fs-uuid --set
76bfc41b-14e7-4e30-8da1-901b14323a1a
        echo    'Loading Linux 2.6.32-5-686-bigmem ...'
        linux   /boot/vmlinuz-2.6.32-5-686-bigmem
root=UUID=76bfc41b-14e7-4e30-8da1-901b14323a1a
        echo Loading initial ramdisk ...
        initrd /boot/initrd.img-2.6.32-5-686-bigmem
}

That's all. Hope it will help... in case of any hints what to do or if
you need more information, let me know. I know this is bugreport, not
helpdesk, though. :)

Cheers,
jimo