On Tue, 21 Nov 2006 21:13:00 +0100, "Henrik Holst"
[off-list ref] said:

quoted

Having a great deal of difficulty getting my 3 disk RAID 5 array to
reappear on restart, Ubuntu 6.10.  

... < snip > ...

quoted

the only way I can get
the RAID Array to assemble is to issue the following:

mknod -m 0660 /dev/md0 b 9 0
mdadm --assemble /dev/md0 /dev/sda1 /dev/sdb1 /dev/sdc1

Try "dpkg-reconfigure mdadm" as root. Under Debian this will give you
the chance to configure the startup configuration for all software raids
in the system. Under any cirtumstances you should not have to use mknod.
Instead try adding the --auto=yes switch to mdadm. Then mdadm will
create the node itself.

That's the one!  Blowing away my current mdadm.conf and issuing a
dpkg-reconfigure mdadm bought my raid online with the subsequent reboot
- I am very greatful!  Now I guess I would like to know where I go wrong
:)

I created the raid in the first place by issuing a:

# sudo mdadm --create --verbose /dev/md0 --level=5 --raid-devices=3 \
/dev/sda1 /dev/sdb1 /dev/sdc1

After this, no mdadm.conf file was created for me, so I made by own by
issuing:

# mdadm --detail --scan >> /etc/mdadm/mdadm.conf

And thats when the whole "assemble" on boot problem came from.  I
presume that the above command (--detail --scan)  is not the correct way
to make the mdadm.conf file - how should it be made?

Finally, on a side note, I have formatted this array (/dev/md0) with
ext3, I planned to exapand the array in the future by adding extra disks
- I presume I can do this with 'mdadm --grow' (and some extra research!
:)  Am I correct on this assumption?

Thanks again
John.