On Tue, 19 Nov 2013 17:34:29 -0800 "David F." [off-list ref] wrote:

Contents of /proc/partitions:
major minor  #blocks  name

   8       32  143638992 sdc
   8       33     102400 sdc1
   8       34  143535568 sdc2
   8       48  143638992 sdd
   8       64  143638992 sde
   8       80  143638992 sdf
   8       81     102400 sdf1
   8       82  143535568 sdf2
   8       96  143638992 sdg
  11        0      48160 sr0
   8       16    7632892 sdb

This seems to suggest that there are no md devices that are active.

Contents of /proc/mdstat (Linux software RAID status):
Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5]
[raid4] [multipath]
md127 : inactive sdg[0](S)
      1061328 blocks super external:ddf

unused devices: <none>

And this confirms it - just md127 which is inactive and is a ddf 'container'.

Contents of /etc/mdadm/mdadm.conf (Linux software RAID config file):
# mdadm.conf
#
# Please refer to mdadm.conf(5) for information about this file.
#

# by default (built-in), scan all partitions (/proc/partitions) and all
# containers for MD superblocks. alternatively, specify devices to scan, using
# wildcards if desired.
DEVICE partitions containers

# automatically tag new arrays as belonging to the local system
HOMEHOST <system>

ARRAY metadata=ddf UUID=7ab254d0:fae71048:404edde9:750a8a05
ARRAY container=7ab254d0:fae71048:404edde9:750a8a05 member=0
UUID=45b3ab73:5c998afc:01bbf815:12660984

This shows that mdadm is expecting a container with
      UUID=7ab254d0:fae71048:404edde9:750a8a05
which is presumably found, and a member with
      UUID=45b3ab73:5c998afc:01bbf815:12660984
which it presumably has not found.

quoted

quoted

mdadm --examine --scan

ARRAY metadata=ddf UUID=7ab254d0:fae71048:
404edde9:750a8a05
ARRAY container=7ab254d0:fae71048:404edde9:750a8a05 member=0
UUID=5337ab03:86ca2abc:d42bfbc8:23626c78

This shows that mdadm found a container with the correct UUID, but the member
array inside the container has the wrong uuid.

Martin: I think one of your recent changes would have changed the member UUID
for some specific arrays because the one that was being created before wasn't
reliably stable.  Could  that apply to David's situation?

David: if you remove the "UUID=" part for the array leaving the
"container=.... member=0" as the identification, does it work?

quoted

quoted

mdadm --assemble --scan --no-degraded -v

mdadm: looking for devices for further assembly
mdadm: /dev/md/ddf0 is a container, but we are looking for components
mdadm: no RAID superblock on /dev/sdf
mdadm: no RAID superblock on /dev/md/MegaSR2
mdadm: no RAID superblock on /dev/md/MegaSR1
mdadm: no RAID superblock on /dev/md/MegaSR

This seems to suggest that there were 3 md arrays active, where as the
previous data didn't show that.  So it seems the two sets of information are
inconsistent and any conclusions I draw are uncertain.

NeilBrown