At boot time I get a question if I want to start it in defraded state. I say "y", and still get this:
mdadm: CREATE user root not found
mdadm: CREATE group disk not found
[26.065844] bio: create slab <bio-1> at 1
[26.065906] md: personality for level is not loaded!
mdadm: failed to start array /dev/md0: invalid argument
mdadm: CREATE user root not found
mdadm: CREATE group disk not found
mdadm: /dev/md0 is already in se.
Could not start the RAID in degraded mode.
Dropping to a shell.
my mdadm.conf says
CREATE owner=root group=disk mode=0660 auto=yes
HOMEHOST <system>
MAILADDR xxx@gmail.com
ARRAY /dev/md0 UUID=953a0832:59d3922f:c3b7e12c:0dda0868
needless to say, mdadm -D /dev/md0 says "does not appear to be active". But the funny thing is that remaining drives appear as spares...

/dev/sdb1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 953a0832:59d3922f:c3b7e12c:0dda0868
Name : sphynx:0 (local to host sphynx)
Creation Time : Wed May 2 19:32:14 2012
Raid Level : -unknown-
Raid Devices : 0
Avail Dev Size : 3900700672 (1860.00 GiB 1997.16 GB)
Data Offset : 2048 sectors
Super Offset : 8 sectors
State : active
Device UUID : 64ba297a:f73ede16:975d6411:fbf2dcae
Update Time : Wed Sep 12 21:38:51 2012
Checksum : ac1d544 - correct
Events : 1
Device Role : spare
Array State : ('A' == active, '.' == missing)

/dev/sdc1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 953a0832:59d3922f:c3b7e12c:0dda0868
Name : sphynx:0 (local to host sphynx)
Creation Time : Wed May 2 19:32:14 2012
Raid Level : -unknown-
Raid Devices : 0
Avail Dev Size : 3900700672 (1860.00 GiB 1997.16 GB)
Data Offset : 2048 sectors
Super Offset : 8 sectors
State : active
Device UUID : 18d85a16:30978466:0a0e2192:50e3d7fc
Update Time : Wed Sep 12 21:38:51 2012
Checksum : c550ebfa - correct
Events : 1
Device Role : spare
Array State : ('A' == active, '.' == missing)

/dev/sdd1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 953a0832:59d3922f:c3b7e12c:0dda0868
Name : sphynx:0 (local to host sphynx)
Creation Time : Wed May 2 19:32:14 2012
Raid Level : -unknown-
Raid Devices : 0
Avail Dev Size : 3900700672 (1860.00 GiB 1997.16 GB)
Data Offset : 2048 sectors
Super Offset : 8 sectors
State : active
Device UUID : b2646441:bf306e17:9dcff561:e84c4e8f
Update Time : Wed Sep 12 21:38:51 2012
Checksum : 38f3d4f - correct
Events : 1
Device Role : spare
Array State : ('A' == active, '.' == missing)
So, when I run mdadm -A /dev/md0 /dev/sd[bcd]1, it says something like "3 spares, 0 drives, not enough stuff"...

Does anybody have any ideas what may be going on?