Re: mdadm confusion

On Thu, 2017-08-24 at 18:06 -0400, Jeffrey Ross wrote: > 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. My mdadm.conf uses /dev/md1 for "boot" and I have a "name" directive in it and my /dev/md/ links were not being created either, so I simply added a line (as shown below) to rc.local to created them each boot if they were not being created. I figure that if something changes that fixes this oddity then it does not matter since I am using `if` to check and to only create the link if it is not already there. # sample line, remember that it should not be wrapped: if [ -b /dev/md1 ] ; then if [ ! -L /dev/md/boot ]; then /bin/ln -s /dev/md1 /dev/md/boot ; fi ; fi