mdadm confusion

Thursday, 24 August 2017

system is Fedora 26, all current updates

I'm running raid1, two identical 500GB disks partitioned as follows:

/dev/sda1            2048 789501951 789499904 376.5G fd Linux raid 
autodetect
/dev/sda2       789501952 948973567 159471616    76G fd Linux raid 
autodetect
/dev/sda3       948973568 975749119  26775552  12.8G fd Linux raid 
autodetect
/dev/sda4       975749120 976773119   1024000   500M  5 Extended
/dev/sda5  *    975751168 976773119   1021952   499M fd Linux raid 
autodetect

raid volumes:

    cat /proc/mdstat
    Personalities : [raid1]
    md124 : active raid1 sdb1[0] sda1[1]
           394617856 blocks super 1.2 [2/2] [UU]
           bitmap: 0/3 pages [0KB], 65536KB chunk

    md125 : active raid1 sda5[1] sdb5[0]
           510656 blocks super 1.2 [2/2] [UU]
           bitmap: 0/1 pages [0KB], 65536KB chunk

    md126 : active raid1 sda2[1] sdb2[0]
           79670272 blocks super 1.2 [2/2] [UU]
           bitmap: 1/1 pages [4KB], 65536KB chunk

    md127 : active (auto-read-only) raid1 sda3[1] sdb3[0]
           13379584 blocks super 1.2 [2/2] [UU]

    unused devices: <none>

Mounted partitions:

    /dev/md126      79631372  5608820  74022552   8% /
    /dev/md124     388294468 23798252 344748940   7% /home
    /dev/md125        486308   283858    172822  63% /boot

md127 is swap

I get the following error in logwatch:

  mdadm: cannot open /dev/md/boot: No such file or directory
  mdadm: cannot open /dev/md/root: No such file or directory
  mdadm: cannot open /dev/md/swap: No such file or directory

and I see that /dev/md contains the following:

# ls -l /dev/md
total 0
lrwxrwxrwx 1 root root 8 Aug 24 16:14 home -> ../md124
lrwxrwxrwx 1 root root 8 Aug 24 16:14 xyzzy2.bubble.org:boot -> ../md125
lrwxrwxrwx 1 root root 8 Aug 24 16:14 xyzzy2.bubble.org:root -> ../md126
lrwxrwxrwx 1 root root 8 Aug 24 16:14 xyzzy2.bubble.org:swap -> ../md127

the entries in /etc/mdadm.conf are:

MAILADDR root
AUTO +imsm +1.x -all
ARRAY /dev/md/boot level=raid1 num-devices=2 
UUID=3b187b00:b3b1a1f9:6d75f8f1:62f82999
ARRAY /dev/md/home level=raid1 num-devices=2 
UUID=d124bd7f:80519efc:a28d80db:617eafed
ARRAY /dev/md/root level=raid1 num-devices=2 
UUID=aed6ed78:840451fc:f101760f:79960f8a
ARRAY /dev/md/swap level=raid1 num-devices=2 
UUID=f84d0bd4:fe7be888:c048d500:cca10896

I have verified that the UUID numbers do match the respective volume names.

so obviously the reason for the error is boot, root, and swap don't 
exist, if I create a symbolic links the error will go away until the 
next reboot.  The question is what triggers making the symbolic links at 
boot time, is it /etc/mdadm.conf and do I simply rebuild it? and how can 
I change them from the hostname to be root, boot, and swap or change the 
mdadm command to look for the hostname entry?

If I run "mdadm --detail --scan" I get the following;
ARRAY /dev/md/xyzzy2.bubble.org:swap metadata=1.2 
name=xyzzy2.bubble.org:swap UUID=f84d0bd4:fe7be888:c048d500:cca10896
ARRAY /dev/md/xyzzy2.bubble.org:root metadata=1.2 
name=xyzzy2.bubble.org:root UUID=aed6ed78:840451fc:f101760f:79960f8a
ARRAY /dev/md/xyzzy2.bubble.org:boot metadata=1.2 
name=xyzzy2.bubble.org:boot UUID=3b187b00:b3b1a1f9:6d75f8f1:62f82999
ARRAY /dev/md/home metadata=1.2 name=xyzzy2.bubble.org:home 
UUID=d124bd7f:80519efc:a28d80db:617eafed

the array names are changed to match what is actually in /dev/md, 
however before I change the entries in mdadm.conf I want to make sure 
I'm not going to cause myself grief and have to log directly on the 
console of the system which is about 30 min and a phone call or two away.

Thanks,
Jeff