stacked raid devices not autodetected?

I have several raid devices that I created with the following
commands:

    mdadm --create /dev/md0 --level=mirror --raid-devices=2 /dev/sd{b,h}1
    mdadm --create /dev/md1 --level=mirror --raid-devices=2 /dev/sd{c,i}1
    mdadm --create /dev/md2 --level=mirror --raid-devices=2 /dev/sd{d,j}1
    mdadm --create /dev/md3 --level=mirror --raid-devices=2 /dev/sd{e,k}1
    mdadm --create /dev/md4 --level=mirror --raid-devices=2 /dev/sd{f,l}1
    mdadm --create /dev/md5 --chunk=256 --level=stripe --raid-devices=5 /dev/md{0,1,2,3,4}

On boot, the kernel automatically detects and starts md0 through md4.
However, md5 is *not* autodetected.  Using the RAID_AUTORUN ioctl also
has no effect.  The only way I've found to reliably start md5 is to
have rc.sysinit run "mdadm -assemble --scan".

Is this a bug?  A design limitation?  Something else?

(I am currently using kernel-2.6.9-1.675_EL on the RHEL 4AS beta.  But
I've never been able to get autodetection of stacked raid devices to
work using any kernel.)

-- 
James Ralston, Information Technology
Software Engineering Institute
Carnegie Mellon University, Pittsburgh, PA, USA

On boot, the kernel automatically detects and starts md0 through md4.
However, md5 is *not* autodetected.  Using the RAID_AUTORUN ioctl also
has no effect.  The only way I've found to reliably start md5 is to
have rc.sysinit run "mdadm -assemble --scan".

Is this a bug?  A design limitation?  Something else?

this is one of the limitations of the in-kernel autodetection

(I am currently using kernel-2.6.9-1.675_EL on the RHEL 4AS beta.  But
I've never been able to get autodetection of stacked raid devices to
work using any kernel.)

if you are not booting from the stacked raid device you can safely have
mdadm called from rc.sysinit, if you are you better use mdassemble in
initrd.

Regards,
L.


-- 
Luca Berra -- bluca@comedia.it
        Communication Media & Services S.r.l.
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