/dev/md[12] vanished

[Kevin H. Hobbs]

On October 4 this :

--------------------- Mdadm Begin ------------------------

mdadm: cannot open /dev/md1: No such file or directory
 /dev/md1 :
 mdadm: cannot open /dev/md2: No such file or directory
 /dev/md2 :

---------------------- Mdadm End -------------------------

and this :

--------------------- Disk Space Begin ------------------------

Filesystem      Size  Used Avail Use% Mounted on
 devtmpfs        2.0G     0  2.0G   0% /dev
 /dev/md127       48G   16G   31G  34% /
 /dev/md126      475M  118M  328M  27% /boot
 /dev/sdc1       917G   73G  798G   9% /mnt/WD1TB
 /dev/md0        173G   65G  101G  40% /home

---------------------- Disk Space End -------------------------

began appearing in the logwatch e-mails of at least two of my
computers that run Fedora 18.

Somehow md1 and md2 became md127 and md126.

On October 3 and 4 there were lots of updates including a kernel
and dracut.

Does anybody have a clue what might have changed?

Everything works from my perspective but I don't want my arrays
to disappear on me if I haven't made some configuration change
before some later update

[Roberto Ragusa]

On 11/16/2013 01:37 PM, Kevin H. Hobbs wrote:
> Somehow md1 and md2 became md127 and md126.

I remember similar behaviors in the past, it looks like
autodetected arrays are assigned high numbers instead of low ones.

One solution (or workaround) is to have a /etc/mdadm.conf file.

MAILADDR root
AUTO +imsm +1.x -all
ARRAY /dev/md0 level=raid1 num-devices=2 UUID=xxxxxxxx:xxxxxxxx:xxxxxxxx:xxxxxxxx
ARRAY /dev/md1 level=raid1 num-devices=2 UUID=xxxxxxxx:xxxxxxxx:xxxxxxxx:xxxxxxxx

(replace things where appropriate, including the xxx)

And then force dracut to rebuild the boot image.