If having both programs installed causes the issue, then each should me 
marked as breaking the other.  I was not trying to run both kinds of 
RAID at once, only to run an mdadm raid with both PROGRAMS installed, 
using partitions on disks I had not been able to set up the dmraid on.  Worked 
fine until Saturday.

I originally tried to set the disks up with dmraid last week, but could
not reliably get a device to come up. This was my first work with any
kind or RAID.

I gave up on using dmraid when I could not bring it up after booting,
and set up an mdadm raid, but left the dmraid program installed and did
not attempt to remove the code written to the disks by the BIOS. I just
set the BIOS back to "AHCI" and proceeded to set up the mdadm raid,
having had no luck with dmraid. It worked fine until Saturday, when I
installed the updates from March 15 and 16 and got the new version of
dmraid. The the trouble began.

 I had thought that using disks not set up in the BIOS for dmraid would
in fact fix this, but when I tried to boot with the backup disks in
place on Saturday, I got the resets I was unable to replicate today.
That was both with and without any disks setup for dmraid hooked up.

I have no way to test dmraid with mdadam not installed, as I have no
disks not in use to set up with dmraid MBR code and test with mdadm not
installed. When I did some retests today with both "marked" disks, when
mdadm did not come up due to partition tables not read (NOT supposed to
be default according to the manpage) and mdadm set up only on partitions
on the disks (not the whole disks), I checked to see if the original
dmraid set up with the chipset was recognized. It was partially but not
fully recognized, did not show up at all with earlier versions. Until
the last update, cat /dev/dm-0 would return no output, now it will
return a bunch of %$&& stuff, indicating the device is partially
readable. Unfortunatley it is not seen as a multidisk volume and comes
up as a 1.8 TB disk instead of a 4TB RAID 0 volume.

With the mdadm raid on partitions only, the mdadm raid should be
entirely ignored by dmraid if neither partition table is read-unless
mdadm code is conflicting with and disabling dmraid code. In that case,
mdadm breaks dmraid, and dmraid breaks mdadm at this time.

I was only trying to bring up the original chipset RAID as a test,
nothing more, MDADM raid is far more portable across motherboards and
you say it performs just as well. At any rate, with over a TB on it, I
am committed to staying with mdadm RAID, not dmraid. This bug report was
only filed because the update caused a problem not originally present.
Not going to screw with the MBR on hy data disks, don't want to corrupt
the partition tables, so that test is out of the question.

> Date: Tue, 20 Mar 2012 00:11:52 +0000
> From: [email protected]
> To: [email protected]
> Subject: [Bug 958334] Re: dmraid_1.0.0.rc16-4.1ubuntu7 blocks reading some    
> disks, resets others
> 
> You keep saying mdadm, which is not dmraid.  You can not use both on the
> same drives at the same time.  Were those typos and you meant dmraid, or
> are you actually trying to mix the two?  If you are mixing them, then
> you need to pick one and stick with it.  Trying to use mdadm on disks
> that are also part of a fakeraid could explain the issues you are
> having.
> 
> dmraid does not care what chipset you have or what mode it is in; it
> will activate the array regardless.  The only difference the AHCI/RAID
> setting makes is to windows and the bios, so if you are booting Linux
> from some other disk, this setting makes no difference.
> 
> -- 
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/958334
> 
> Title:
>   dmraid_1.0.0.rc16-4.1ubuntu7  blocks reading some disks, resets others
> 
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/ubuntu/+source/dmraid/+bug/958334/+subscriptions

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Title:
  dmraid_1.0.0.rc16-4.1ubuntu7  blocks reading some disks, resets others

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