[Bug 1349986] Comment bridged from LTC Bugzilla

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------- Comment From thadeul at br.ibm.com 2015-02-02 16:26 EDT-------
I will expand a little more on what I found out about the bug, and where it likely is.

As I described in the initial report, the UUID device that is used by
the scripts to lookup for the rootfs is pointing out to a SCSI partition
device.

For example:

/dev/disk/by-uuid/78c02bb3-9623-4fe0-b283-22f8f3fe8faa -> /dev/sda2

multipath daemon has already detected the multipath setup and created a
mapping that uses sda, and creates linear mappings to the partitions
using kpartx.

/dev/mapper/mpathap2 -> ../dm-2
/dev/mapper/mpatha -> ../dm-0

The UUID device should point to dm-2 or mpathap2 instead of pointing out
to sda2. This is needed because the mpath mapping will grab the device
and that will prevent a filesystem to be mounted directly on it.

The UUID device is created by udev. udev is creating that during the
device probe. When the multipath partition is created, udev reads the
same filesystem UUID there, but can't create the link because it already
exists. What needs to be done is removing that link when multipath is
detected or sda2 is removed from the system, or forcing the link
creation when it already exists.

Cascardo.

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https://bugs.launchpad.net/bugs/1349986

Title:
  Ubuntu fails to boot with multipath

Status in multipath-tools package in Ubuntu:
  Confirmed

Bug description:
  ---Problem Description---
  When multipath boot support is on, the system fails to boot. Basically, the UUID device points to the underlying SCSI partition device instead of the multipath partition device when initramfs script tries to mount it.
   
  ---uname output---
  Linux (none) 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:50:31 UTC 2014 ppc64le GNU/Linux
   
  ---Additional Hardware Info---
  IPR multipath system. 
   
  Machine Type = 8286-42A 
    
  ---Steps to Reproduce---
  Install the system into a multipath device, then install multipath-tools-boot, reboot.
   
  Userspace tool common name: udev

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