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[Brad Figg <brad.figg@xxxxxxxxxxxxx>]

This bug is missing log files that will aid in diagnosing the problem.
>From a terminal window please run:

apport-collect 1446786

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable
to run this command, please add a comment stating that fact and change
the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the
Ubuntu Kernel Team.

** Changed in: linux (Ubuntu)
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1446786

Title:
  Wrong read balance when a drive is write-mostly

Status in linux package in Ubuntu:
  Incomplete

Bug description:
  This bug related to `mdadm` `--write-mostly` option. When we create
  SSD for read operation, but want to use HDD to mirror SSD content we
  can create RAID-1 with SSD and 'write-mostly' HDD disk.

  In Ubuntu kernel there is a bug, which lead to havy read from both SSD
  and HDD drives. More over if we add HDD as regular disk and SSD as a
  'write-mostly' replica most read operations will go to SSD drive
  (which is clear from sources and we have prove it in our setup).

  In upstream kernel sources this was already fixed:

  https://github.com/torvalds/linux/commit/63a7d0a9160421a23baac407847e484e8488d12a

  Could you backport this functionality? - This patch looks safe to
  apply as is.

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