Software RAID 0+1 with mdadm.

[Brad Dameron <brad@seatab.com>]

Been trying for days to get a software RAID 0+1 setup. This is on SuSe
9.2 with kernel 2.6.8-24.11-smp x86_64.

I am trying to setup a RAID 0+1 with 4 250gb SATA drives. I do the
following:

mdadm --create /dev/md1 --level=0 --chunk=4 --raid-devices=2 /dev/sdb1
/dev/sdc1
mdadm --create /dev/md2 --level=0 --chunk=4 --raid-devices=2 /dev/sdd1
/dev/sde1
mdadm --create /dev/md0 --level=1 --chunk=4 --raid-devices=2 /dev/md1
/dev/md2

This all works fine and I can mkreiserfs /dev/md0 and mount it. If I am
then to reboot /dev/md1 and /dev/md2 will show up in the /proc/mdstat
but not /dev/md0. So I create a /etc/mdadm.conf like so to see if this
will work:

DEVICE partitions
DEVICE /dev/md*
ARRAY /dev/md2 level=raid0 num-devices=2
UUID=5e6efe7d:6f5de80b:82ef7843:148cd518
   devices=/dev/sdd1,/dev/sde1
ARRAY /dev/md1 level=raid0 num-devices=2
UUID=e81e74f9:1cf84f87:7747c1c9:b3f08a81
   devices=/dev/sdb1,/dev/sdc1
ARRAY /dev/md0 level=raid1 num-devices=2  devices=/dev/md2,/dev/md1


Everything seems ok after boot. But again no /dev/md0 in /proc/mdstat.
But then if I do a mdadm --assemble --scan it will then load /dev/md0. 

Also do I need to create partitions? Or can I setup the whole drives as
the array?

I have since upgraded to mdadm 1.8 and setup a RAID10. However I need
something that is production worthy. Is a RAID10 something I could rely
on as well? Also under a RAID10 how do you tell it which drives you want
mirrored?

Any help appreciated. 

Thank you,
Brad Dameron
SeaTab Software
www.seatab.com