Hello Martin,

On Sat, Aug 24, 2013 at 8:41 PM, Martin Wilck [off-list ref] wrote:

On 08/24/2013 02:42 PM, Francis Moreau wrote:

quoted

On Sat, Aug 24, 2013 at 2:40 PM, Francis Moreau [off-list ref] wrote:

quoted

Hello Martin,

On Fri, Aug 23, 2013 at 9:09 PM, Martin Wilck [off-list ref] wrote:

quoted

On 08/23/2013 12:00 PM, Francis Moreau wrote:

quoted

[ adding Martin in CC since it seems related to DDF... ]

I reproduced it here. The problem is that mdmon isn't running. Simply
try running "mdmon /dev/md127", and the mount should proceed.

oh, ok, I should have noticed.

quoted

You'd avoid the problem by running "mdadm -IR /dev/sda" in the first place.

Actually this is how arrays are assembled during boot on some
distributions (Fedora for example).

I meant the sequence:

mdadm -I /dev/sda
mdadm -I /dev/sdb
mdadm -R /dev/mdxxx

is used by distribution.

CentOS 6 uses the following sequence:

mdadm -I /dev/sda
mdadm -I /dev/sdb
mdadm -I /dev/mdXXX

I don't see mdadm -R anywhere on CentOS.

After digging into the code of dracut, it seems that the bug (mdmon
not started by mdadm -R /dev/mdxxx on incomplete array) seems to be
known and a workaround exists.

Basically the script which starts MD arrays (slightly modified by me
to make it easier to read) does:

for md in /dev/md[0-9_]*; do

    ...

    [ $(cat $md/array_state) != inactive ] && continue

    mdadm --offroot -R $md

    [ $(cat $md/array_state) = inactive ] && continue

    # workaround for mdmon bug
    [ $(cat $md/degraded) -gt 0 ] && mdmon --offroot --takeover $md
done

In theory this should fix the bug but it doesn't (looks like I'm
really unlucky). Indeed at the time the script is run, the container
device doesn't exist in /dev. Therefore the workaround is only
executed on the MD array device. I can see the following message
during the boot: "mdmon: md126 is not a container - cannot monitor"

I tried to add "udevadm settle" before executing the workaround but
that doesn't help.

You could change your udev rules to run "mdadm -IR /dev/mdXXX" instead.
Have you tried that?

I tried and it works fine.

Thanks
-- 
Francis