Building raid0 on Intel ICH9R -- some observations / questions

[Hall, Eric R]

>Observation 1 : The kernel always recognizes three disks (dev/sda,
>dev/sdb, /dev/sdc), even when dmraid is not installed (yet).
And it always will.  Those are the devices, drives, attached to the
system.  Dmraid activates any metadata that is contained on the 'drives'
to create a mapped device in /dev/mapper/

>According
>to what I had read, I had expected that without dmraid only the
"normal"
>disk (/dev/sda) would be recognized.
Nope, device-mapper and dmraid still need to access each disk of the
set.


>fdisk works, but requires a
>reboot before the partition becomes visible (Some Error 22 ...)
Or just deactivate the array (-an) and re-activate it (-ay).  All of the
partitioning tools should work just fine.


>Observation 3 : After the reboot, I have
>/dev/mapper/isw_geiabefhb_<somename>1
>as expected, but I suddenly also have a /dev/sdb1 partition, i.e., a
>partition
>on the first of the two disks forming the raid array.
Sure, that's normal.  You've created a RAID 0 -- data is striped across
multiple drives to make a _large_ 'disk' from those smaller drives.  The
'first' sector of the array will be the first disk of the set -- in your
case that is sdb.  If you look at it on the physical devices then the
partition table is on 'sdb' but it extends to sdc and sdd.


>So, it seems that the partitioning info for the raid device got
>written on the first disk
Correct.

>obviously, when a check is made against the
>physical size of the device, then things don't match.
Correct.  But it doesn't prevent anything from continuing and working.

>So, to make this short: Is this which should have happened. Can I
disregard
>these messages as a nuisance, _or_ is there something fishy going on
...
I'd disregard them.