[bug #38406] GRUB assembles wrong disks for md RAID device

[GigaTux]

URL:
  <http://savannah.gnu.org/bugs/?38406>

                 Summary: GRUB assembles wrong disks for md RAID device
                 Project: GNU GRUB
            Submitted by: gigatux
            Submitted on: Mon 25 Feb 2013 11:25:32 GMT
                Category: Booting
                Severity: Major
                Priority: 5 - Normal
              Item Group: Software Error
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: Marc Warne
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 
                 Release: 1.98
         Reproducibility: Every Time
         Planned Release: None

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Details:

Hi,

I haven't yet attempted to reproduce this as it occurred on a production
system that I needed to get up as soon as I could, but when it was an issue,
it was fully repeatable.

Scenario:

  1. /boot stored on a four disk MD RAID-1 array.
  2. Two disks had failed simultaneously.
  3. Upon GRUB boot, GRUB was assembling the two failed disks (which comprised
a valid but somewhat old filesystem) instead of the two more recently updated
disks.

My best guess is that GRUB isn't taking account the relevant timestamps on the
RAID members which should specify when they were last updated.

It should be possible to reproduce this by failing two md devices
simultaneously and then getting GRUB to use it as its filesystem. I'm not sure
which two would need to fail (e.g. does GRUB just use the devices with the
lowest numbers?) but I think some simple checking of timestamps would be
required.




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