grub2: Some modules may be missing from core image..

[Norberto Bensa]

After upgrading to quantal, grub-install says:

Path `/boot/grub' is not readable by GRUB on boot. Installation is impossible. Aborting.

My setup is 2x1TB raid1 disks. LVM on raid. /boot in LVM. This configuration was working before quantal. Currently I'm rebuilding my raid 'cos it was mdraid10 on GPT, and I tought GPT was making grub-install fail, but now it is mdraid1 on MBR and the problem persists. Maybe it is md or lvm problem (from the message "missing modules from core image").

# dpkg-reconfigure grub-pc says:

Generando grub.cfg ...
/usr/sbin/grub-probe: aviso: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
/usr/sbin/grub-probe: aviso: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
/usr/sbin/grub-probe: aviso: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
/usr/sbin/grub-probe: aviso: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
/usr/sbin/grub-probe: aviso: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
Se encontró una imagen linux: /boot/vmlinuz-3.5.0-17-generic
Se encontró una imagen initrd: /boot/initrd.img-3.5.0-17-generic
/usr/sbin/grub-probe: aviso: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
/usr/sbin/grub-probe: aviso: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
/usr/sbin/grub-probe: aviso: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
/usr/sbin/grub-probe: error: no es un directorio.
Se encontró una imagen linux: /boot/vmlinuz-3.2.0-32-generic
Se encontró una imagen initrd: /boot/initrd.img-3.2.0-32-generic
/usr/sbin/grub-probe: aviso: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
Se encontró una imagen linux: /boot/vmlinuz-3.5.0-17-generic
Se encontró una imagen initrd: /boot/initrd.img-3.5.0-17-generic
/usr/sbin/grub-probe: aviso: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
/usr/sbin/grub-probe: aviso: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
/usr/sbin/grub-probe: aviso: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
/usr/sbin/grub-probe: error: no es un directorio.
Se encontró una imagen linux: /boot/vmlinuz-3.2.0-32-generic
Se encontró una imagen initrd: /boot/initrd.img-3.2.0-32-generic
/usr/sbin/grub-probe: aviso: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
/usr/sbin/grub-probe: aviso: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
/usr/sbin/grub-probe: aviso: Couldn't find physical volume `(null)'. Some modules may be missing from core image..
/usr/sbin/grub-probe: error: no es un directorio.
Found memtest86+ image: /memtest86+.bin
Encontrado en Windows 7 (loader) en /dev/sdc1
Encontrado en Ubuntu 12.04.1 LTS (12.04) en /dev/mapper/venkman-LXC--django
Encontrado en Ubuntu 12.04.1 LTS (12.04) en /dev/mapper/venkman-LXC--maria
Encontrado en Ubuntu 12.04 LTS (12.04) en /dev/mapper/venkman-LXC--monitoring
Encontrado en Ubuntu 12.04 LTS (12.04) en /dev/mapper/venkman-LXC--samba3
Encontrado en Ubuntu 12.04.1 LTS (12.04) en /dev/mapper/venkman-LXC--samba4
hecho

# LC_ALL=C fdisk -l /dev/sda

Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
81 heads, 63 sectors/track, 382818 cylinders, total 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0007dfde

   Device Boot Start End Blocks Id System
/dev/sda1 2048 1953525167 976761560 fd Linux raid autodetect

# LC_ALL=C fdisk -l /dev/sdb

Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes
81 heads, 63 sectors/track, 382818 cylinders, total 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00092d82

   Device Boot Start End Blocks Id System
/dev/sdb1 2048 1953525167 976761560 fd Linux raid autodetect

# mdadm -QD /dev/md1
/dev/md1:
        Version : 1.2
  Creation Time : Thu Oct 18 01:01:04 2012
     Raid Level : raid1
     Array Size : 976630336 (931.39 GiB 1000.07 GB)
  Used Dev Size : 976630336 (931.39 GiB 1000.07 GB)
   Raid Devices : 2
  Total Devices : 2
    Persistence : Superblock is persistent

    Update Time : Thu Oct 18 10:45:54 2012
          State : clean, degraded, recovering
 Active Devices : 1
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 1

 Rebuild Status : 52% complete

           Name : venkman:1 (local to host venkman)
           UUID : 9a5a5452:6637c622:a13521f7:3e865bae
         Events : 14392

    Number Major Minor RaidDevice State
       0 8 17 0 active sync /dev/sdb1
       2 8 1 1 spare rebuilding /dev/sda1

# pvs
  PV VG Fmt Attr PSize PFree
  /dev/md1 venkman lvm2 a-- 931,38g 186,26g

# mount | grep boot
/dev/mapper/venkman-boot on /boot type ext3 (rw,noatime)

[Norberto Bensa (nbensa)]

Update to this problem.

This bug kicks in when /boot is a separated partition from /

[Norberto Bensa (nbensa)]

I will close this one for now because after merging /boot and separate it again, now grub-install works and pc boots perfectly with separated /boot partition. I don't know what happend. Maybe a configuration problem, a partition problem.

Will reopen if happens again.

Thanks!

[Alkis Georgopoulos (alkisg)]

I won't reopen it because it's not exactly the same issue, but since it was one of the first google hits for my problem, I'll note here that I too got the message:
  /usr/sbin/grub-probe: warning: Couldn't find physical volume `(null)'. Some modules may be missing from core image..

...and, like mentioned in http://serverfault.com/questions/617552/grub-some-modules-may-be-missing-from-core-image-error, it was due to my newly-created md RAID being still in degraded mode.

After a few hours when the RAID array has synced, I ran update-grub again and the error went away.