What I did to make it work was add nodmraid to kernel parameter - but
since I need to use dmraid sometimes and I want to use the init script
to handle it, I removed 63-md-raid-array.rules and 85-dmraid.rules
from udev so raid doesn't try to automatically start at boot.

However, when trying to do: mdadm --assemble --scan --no-degraded -v

you end up with:

mdadm: looking for devices for further assembly
mdadm: Cannot assemble mbr metadata on /dev/sdc1
mdadm: Cannot assemble mbr metadata on /dev/sdc
mdadm: Cannot assemble mbr metadata on /dev/sda5
mdadm: Cannot assemble mbr metadata on /dev/sda3
mdadm: Cannot assemble mbr metadata on /dev/sda2
mdadm: no recongnizeable superblock on /dev/sda1
mdadm: /dev/sda is identified as a member of /dev/md/imsm0, slot 0.
mdadm: /dev/sdb is identified as a member of /dev/md/imsm0, slot 1.
mdadm: added /dev/sdb to /dev/md/imsm0 as 1
mdadm: added /dev/sda to /dev/md/imsm0 as 0
mdadm: timeout waiting for /dev/md/imsm0
mdadm: looking for devices for further assembly
mdadm: looking for devices for further assembly
mdadm: Cannot assemble mbr metadata on /dev/sdc1
mdadm: Cannot assemble mbr metadata on /dev/sdc
mdadm: Cannot assemble mbr metadata on /dev/sda5
mdadm: Cannot assemble mbr metadata on /dev/sda3
mdadm: Cannot assemble mbr metadata on /dev/sda2
mdadm: no recongnizeable superblock on /dev/sda1
mdadm: /dev/sda is busy - skipping
mdadm: /dev/sdb is busy - skipping
mdadm: cannot open device /dev/md/imsm0: No such file or directory

If I left the rules in place, dmraid takes over, if I do this:

dmsetup remove_all
mdadm --assemble --scan --no-degraded -v

then it comes up fine as well.

Help!
Thanks.



On Sat, Aug 13, 2022 at 4:02 PM David F. [off-list ref] wrote:

So it does have something to with the mapper devices.   If I add
"nodmraid" kernel parameter then mdadm raid works like it did before.
 I want searching config parameters for the kernel to see if I enabled
DMRAID somehow but didn't find any.   Why is the new disk/updated
programs automatically starting dmraid?   could it be udev rules .. I
don't really understand them .. but dmraid is an option for non intel
type raid, so what happens is dmraid is tried first for all but the
intel items, then mdadm is used.  But this is not coming from my call
of dmraid, it's coming from someplace automatic ??

On Sat, Aug 13, 2022 at 12:58 PM David F. [off-list ref] wrote:

quoted

I have an older system with Intel RAID (striped) I use to test updates
to my linux boot disk to ensure the RAID is still working.  I just
went through a big update of all the utilities and shared libraries
along with moving from 5.10 to 5.15 kernel.  There was a stage where
the kernel was updated to 5.15 but all the utilities and shared
libraries were not (and md raid was working).  The problem is now
there are no md devices created, but there are a bunch of dm devices
created that never were before.

This group has been very helpful in the past.  I hope you can help
with what is going on here?  Does it have something to do with the
updated devmapper ?  Should I revert?

I put both the old working information and the new information below -
separated by the 3 lines of equals.