On Fri, Jul 19, 2013 at 8:52 PM, Martin Wilck [off-list ref] wrote:

quoted

Yes, but my question is about how md cooperate with the BIOS in this case ?

Not sure what you mean. When Linux runs, with or without MD, no BIOS
code is ever executed.

Ok I think I'm missing something more fundamental here.

For exemple when writing to the disk, each write goes into the 2 disks
in case of RAID1. When Linux runs, is it either DM or MD (and
necessarily one of them) that does this work ?

For windows case, does it relies on a driver that is provided by the
RAID manufacturer ?

The only way of communication between BIOS and MD is the meta data. When
you create an array in your BIOS setup tool, The BIOS will write the
meta data. MD will read it, and when it's done, it will re-write it
(usually unchanged, unless a disk failure occurs, but there are some
fields such as sequential numbers and time stamps that change every time
the meta data is written). The BIOS will read this back the next time
your system boots.

quoted

Are there any procedures described out there that I could follow to
test MD DFF ?

Not really. Play around, test various RAID levels etc, whatever your
fake RAID supports. If you have a Linux or Windows driver for your fake
raid, check if it correctly detects your setup after MD had control.

Note that RAID arrays *created* by MD (with mdadm -C) will most probably
not be accepted by the BIOS (it will consider them "foreign
configurations" and not import them).

Thanks for those information.
--
Francis