[Bug 900393] Re: Won't boot if grub on partition holding the LVM root fs

Thu Oct 10 20:11:35 UTC 2013

** Changed in: util-linux (Ubuntu)
       Status: New => Triaged

** Changed in: util-linux (Ubuntu)
   Importance: Undecided => Medium

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https://bugs.launchpad.net/bugs/900393

Title:
  Won't boot if grub on partition holding the LVM root fs

Status in “util-linux” package in Ubuntu:
  Triaged

Bug description:
  $ apt-cache policy libblkid1
  libblkid1:
    Installed: 2.19.1-2ubuntu3
    Candidate: 2.19.1-2ubuntu3
    Version table:
   *** 2.19.1-2ubuntu3 0
          500 http://gb.archive.ubuntu.com/ubuntu/ oneiric/main amd64 Packages
          100 /var/lib/dpkg/status

  blkid will fail to report a partition as a "LVM2 Member" if it
  contains a grub boot sector.

  On Ubuntu 11.10 where VGs are activated by udev upon finding LVM
  physical volumes (as opposed to "lvm vgchange -ay" being run
  unconditionally in earlier versions), that means that it won't boot as
  it won't find the root FS:

  <pre>
  Gave up waiting for root device.  Common problems:
   - Boot args (cat /proc/cmdline)
     - Check rootdelay= (did the system wait long enough?)
     - Check root= (did the system wait for the right device?)
   - Missing modules (cat /proc/modules; ls /dev)
  ALERT!  /dev/mapper/VG_linux-ubuntu64 does not exist.  Dropping to a shell!

  BusyBox v1.18.4 (Ubuntu 1:1.18.4-2ubuntu2) built-in shell (ash)
  Enter 'help' for a list of built-in commands.
  (initramfs) blkid -o udev -p /dev/vda4
  ID_PART_TABLE_TYPE=dos
  ID_PART_ENTRY_SCHEME=dos
  ID_PART_ENTRY_TYPE=0x8e
  ID_PART_ENTRY_FLAGS=0x80
  ID_PART_ENTRY_NUMBER=4
  (initramfs) lvm vgchange -ay
    5 logical volume(s) in volume group "VG_linux" now active
  (initramfs) lvm pvs
    PV         VG       Fmt  Attr PSize   PFree
    /dev/vda4  VG_linux lvm2 a-   771.30g 503.30g
  </pre>

  It can be reproduced with the PV on a partition or on a full disk such
  as with this script:

  <pre>
  #! /bin/sh -
  set -ex
  truncate -s 1T test
  qemu-nbd -c /dev/nbd0 test
  sleep 1
  pvcreate /dev/nbd0
  vgcreate V /dev/nbd0
  : Before grub:
  blkid -o udev -p /dev/nbd0
  xxd -r << \EOF 1<> /dev/nbd0
  0000000: eb63 9000 0000 0000 0000 0000 0000 0000  .c..............
  0000010: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  0000020: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  0000030: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  0000040: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  0000050: 0000 0000 0000 0000 0000 0080 7eb0 0300  ............~...
  0000060: 0000 0000 fffa 9090 f6c2 8074 05f6 c270  ...........t...p
  0000070: 7402 b280 ea79 7c00 0031 c08e d88e d0bc  t....y|..1......
  0000080: 0020 fba0 647c 3cff 7402 88c2 52be 807d  . ..d|<.t...R..}
  0000090: e817 01be 057c b441 bbaa 55cd 135a 5272  .....|.A..U..ZRr
  00000a0: 3d81 fb55 aa75 3783 e101 7432 31c0 8944  =..U.u7...t21..D
  00000b0: 0440 8844 ff89 4402 c704 1000 668b 1e5c  . at .D..D.....f..\
  00000c0: 7c66 895c 0866 8b1e 607c 6689 5c0c c744  |f.\.f..`|f.\..D
  00000d0: 0600 70b4 42cd 1372 05bb 0070 eb76 b408  ..p.B..r...p.v..
  00000e0: cd13 730d f6c2 800f 84d8 00be 8b7d e982  ..s..........}..
  00000f0: 0066 0fb6 c688 64ff 4066 8944 040f b6d1  .f....d. at f.D....
  0000100: c1e2 0288 e888 f440 8944 080f b6c2 c0e8  ....... at .D......
  0000110: 0266 8904 66a1 607c 6609 c075 4e66 a15c  .f..f.`|f..uNf.\
  0000120: 7c66 31d2 66f7 3488 d131 d266 f774 043b  |f1.f.4..1.f.t.;
  0000130: 4408 7d37 fec1 88c5 30c0 c1e8 0208 c188  D.}7....0.......
  0000140: d05a 88c6 bb00 708e c331 dbb8 0102 cd13  .Z....p..1......
  0000150: 721e 8cc3 601e b900 018e db31 f6bf 0080  r...`......1....
  0000160: 8ec6 fcf3 a51f 61ff 265a 7cbe 867d eb03  ......a.&Z|..}..
  0000170: be95 7de8 3400 be9a 7de8 2e00 cd18 ebfe  ..}.4...}.......
  0000180: 4752 5542 2000 4765 6f6d 0048 6172 6420  GRUB .Geom.Hard
  0000190: 4469 736b 0052 6561 6400 2045 7272 6f72  Disk.Read. Error
  00001a0: 0d0a 00bb 0100 b40e cd10 ac3c 0075 f4c3  ...........<.u..
  00001b0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  00001c0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  00001d0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  00001e0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
  00001f0: 0000 0000 0000 0000 0000 0000 0000 55aa  ..............U.
  EOF
  : After grub:
  blkid -o udev -p /dev/nbd0
  : clean-up
  vgchange -an V
  qemu-nbd -d /dev/nbd0
  rm -f test
  </pre>

  Which gives:

  <pre>
  $ sudo sh ./reproduce
  + truncate -s 1T test
  + qemu-nbd -c /dev/nbd0 test
  + sleep 1
  + pvcreate /dev/nbd0
    Writing physical volume data to disk "/dev/nbd0"
    Physical volume "/dev/nbd0" successfully created
  + vgcreate V /dev/nbd0
    Volume group "V" successfully created
  + : Before grub:
  + blkid -o udev -p /dev/nbd0
  ID_FS_UUID=1iWyMS-ZzMm-l7nv-kLTc-V2Rq-CqRo-q4RTnz
  ID_FS_UUID_ENC=1iWyMS-ZzMm-l7nv-kLTc-V2Rq-CqRo-q4RTnz
  ID_FS_VERSION=LVM2\x20001
  ID_FS_TYPE=LVM2_member
  ID_FS_USAGE=raid
  + xxd -r
  + : After grub:
  + blkid -o udev -p /dev/nbd0
  ID_PART_TABLE_TYPE=dos
  + : clean-up
  + vgchange -an V
    0 logical volume(s) in volume group "V" now active
  + qemu-nbd -d /dev/nbd0
  /dev/nbd0 disconnected
  + rm -f test
  </pre>

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