F14 seems to break MD raid?

David Jansen jansen at strw.leidenuniv.nl
Fri Nov 12 11:44:37 UTC 2010


I recently installed Fedora 14 on a couple of computers that were
previously running Fedora 12. These computers have 3 disks, sda
holding /, /usr, swap and a partition called /data1, and sdb and sdc
were configured as a software RAID1 (/dev/md0).

F14 anaconda correcly recognizes the setup, and I could specify /data2
as the mountpoint for /dev/md0, and installation proceeded as expected.

However, after reboot, the raid is broken, and /dev/md0 only has one
member (in this case /dev/sdb1 but in another case it was /dev/sdc1).

I first saw this on an installation using a kickstart file, but retrying
an interactive install gave the same results.

In /var/log/messages:

Nov 12 10:00:01 zegerplas kernel: [   12.396148] md: array md0 already
has disks!
Nov 12 10:00:01 zegerplas kernel: [   13.287474] md/raid1:md0: active
with 1 out of 2 mirrors
Nov 12 10:00:01 zegerplas kernel: [   13.287494] md0: detected capacity
change from 0 to 500105150464
Nov 12 10:00:01 zegerplas kernel: [   13.289101]  md0: unknown partition
table
Nov 12 10:00:01 zegerplas kernel: [   14.567086] EXT4-fs (md0): mounted
filesystem with ordered data mode. Opts: (null)

# cat /proc/mdstat
Personalities : [raid1] 
md0 : active raid1 sdb1[0]
      488383936 blocks [2/1] [U_]
      
Fixable by re-adding /dev/sdb1 to the raid, but after the next reboot,
the problem was back.
Now I noticed that /boot/grub/grub.conf included options rd_NO_MD (and
rd_NO_LUKS and a few more). The problem seems to be fixed if I remove
those options, re-add /dev/sdb1 to the raid, and then reboot. So there
is a workaround, but that's not an optimal solution.

Two questions: 
1. is this a correct workaround, or was the rd_NO_MD boot option there
for a reason and will removing it cause problems?
2. Is there a way to remove this option during installation, to ensure
the raid never gets broken? I think that is a lot safer than allowing
the mirror to break, and then forcing a re-add. It's also more
convenient and there is no risk of forgetting to rebuild the mirror.
Can this be done from a kickstart file? I know the 'bootloader' command
in a kickstart file can add boot options, but how to get rid of unwanted
boot options that seem to be added by default (same is trye when doing
an interactive install, one can add boot options, but that's not what I
seem to need here).


David Jansen

PS: this is sort of similar to
https://bugzilla.redhat.com/show_bug.cgi?id=649038 although in my case,
there is no crash and the system boots in an almost functional state.
But I'll add a note to that bug anyway, in case it helps the developers
track down the issue.



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