On Mon, 18 May 2015 14:29:23 -0600 Hans Malissa [off-list ref] wrote:

I have a software-RAID1 that seems to be working correctly:

# cat /proc/mdstat
Personalities : [raid1] 
md0 : active raid1 sdc1[1] sdb1[0]
      976629568 blocks super 1.2 [2/2] [UU]
      
unused devices: <none>

# mdadm --detail /dev/md0
/dev/md0:
        Version : 1.2
  Creation Time : Sun May 17 15:21:30 2015
     Raid Level : raid1
     Array Size : 976629568 (931.39 GiB 1000.07 GB)
  Used Dev Size : 976629568 (931.39 GiB 1000.07 GB)
   Raid Devices : 2
  Total Devices : 2
    Persistence : Superblock is persistent

    Update Time : Mon May 18 10:28:36 2015
          State : clean 
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           Name : eprb21:0  (local to host eprb21)
           UUID : 0901fe50:444a29b6:d3caff14:e45ef9cc
         Events : 19

    Number   Major   Minor   RaidDevice State
       0       8       17        0      active sync   /dev/sdb1
       1       8       33        1      active sync   /dev/sdc1

But, on the other hand, when the system boots, I briefly see the following messages:

doing fast boot
Creating device nodes with udev
udevd[174]: failed to execute ‘/sbin/mdadm’ ‘/sbin/mdadm --incremental /dev/sdb1

udevd[175]: failed to execute ‘/sbin/mdadm’ ‘/sbin/mdadm --incremental /dev/sdc1 --offroot’: No such file or directory

But otherwise the system appears to run normally. After booting, /dev/md0 seems to be working correctly.
What does it mean, and should I worry about it? What can I do about it? My system is openSUSE 12.2.
Thanks a lot,

I suspect that some udev scripts on the initrd say to run mdadm, but mdadm
isn't installed on the initrd.
/dev/md0 doesn't hold the root filesystem does it?  mdadm is only installed
on the initrd if it is needed for root, swap, or suspend-to-disk.

If you really wanted to get rid of the messages - which are definitely
harmless - you would need to recreate the initrd either without those udev
rules files, or with mdadm.
Adding the 'md' arg to the "mkinitrd" command might be sufficient, but I
don't have a 12.2 install lying around that I can play with.

NeilBrown