Re: Array over arrays - how to autoassemble correctly?

[Luca Berra <bluca@comedia.it>]

On Wed, Jan 27, 2010 at 06:32:57PM +0000, Kristleifur Daðason wrote:
>Hi all,
>
>I'm running a RAID-60 array with mdadm. There are two RAID6 arrays,
>/dev/md/d0 and d1, and then a RAID0 "meta-array" over that,
>/dev/md/tank.
>
>What happens on boot is that the d0 and d1 arrays are assembled, but
>the tank array isn't - Ubuntu drops me to a root shell because it
>couldn't find the tank partition for mounting from fstab. However, I
>just have to do a simple 'mdadm --assemble --scan', and the tank array
>pops up instantly and everything is fine.
>
>How do I instruct mdadm to wait for d0 and d1 and do kind of a second
>assembly pass to construct tank over them?
>
>/proc/mdstat, output of 'mdadm --detail --scan' and
>/etc/mdadm/mdadm.conf are included. I hope that's enough background
>information.

I tested it again, "mdadm --assemble --scan" is able to start stacked
arrays correctly either with a configuration similar to yours or with no
configuration at all !!!
Maybe it is due to how ubuntu tries to assemble your array, i would
guess through udev rules.
Maybe the rules are triggered for real devices (/dev/sd*) and not for
/dev/md*, but im not running ubuntu, so i have no way to know.

Regards,
L.
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