[Bug 876783] [NEW] Incorrect "unknown LVM metadata header" errors when running update-grub

[Phillip Susi]

Public bug reported:

When running update-grub, I get several lines of:

error: unknown LVM metadata header.

This appears to be caused by grub-probe locating the LVM PV label sector
on the underlying physical disk ( hd3,msdos1 ), and incorrectly
following the pointer to the mda header.  At this point, it has already
scanned the 4 physical disks, found the first partition on them, found
the mdadm 1.0 superblock, and correctly located the LVM PV label sector
inside (md/0).  The first few sectors of (md/0) are aliased to
(hd3,msdos1), but obviously the offsets are wrong since they are
relative to the md array, not the disk partition.

I would think that once the mdadm signature was detected on the
underlying physical disk partition, that should preclude further scans
on that partition ( for LVM ).

** Affects: grub2 (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/876783

Title:
  Incorrect "unknown LVM metadata header" errors when running update-
  grub

Status in “grub2” package in Ubuntu:
  New

Bug description:
  When running update-grub, I get several lines of:

  error: unknown LVM metadata header.

  This appears to be caused by grub-probe locating the LVM PV label
  sector on the underlying physical disk ( hd3,msdos1 ), and incorrectly
  following the pointer to the mda header.  At this point, it has
  already scanned the 4 physical disks, found the first partition on
  them, found the mdadm 1.0 superblock, and correctly located the LVM PV
  label sector inside (md/0).  The first few sectors of (md/0) are
  aliased to (hd3,msdos1), but obviously the offsets are wrong since
  they are relative to the md array, not the disk partition.

  I would think that once the mdadm signature was detected on the
  underlying physical disk partition, that should preclude further scans
  on that partition ( for LVM ).

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