Red Hat Bugzilla – Bug 429184
Kernel "forgets" to auto assemble deferred md1 mirror set
Last modified: 2009-01-09 00:48:11 EST
Description of problem:
After passing in the boot flags md=1,/dev/sda2,/dev/sdb2 the kernel appears to
defer auto assembly, but never completes the task.
(from dmesg) "md: Will configure md1 (super-block) from /dev/sda2,/dev/sdb2, below."
However, mirror set md0 does get assembled without kernel flags.
(from dmesg) "raid1: raid set md0 active with 2 out of 2 mirrors"
Version-Release number of selected component (if applicable):
Linux version 18.104.22.168-85.fc8
How reproducible: 100%
Steps to Reproduce:
1. Install 2 120GB sata drives and boot to F8 in rescue mode.
2. Partition each into 60GB drives with partition type 0xfd
3. Set sda1 and sdb1 as bootable.
4. Create arrays with:
mdadm -C /dev/md0 -n 2 -l 1 /dev/sda1 /dev/sdb1
mdadm -C /dev/md1 -n 2 -l 1 /dev/sda2 /dev/sdb2
5. Install F8 (used Unity Respin x86-64) with /dev/md0 as /
7. Kernel auto assembles md0 correctly and boots, but md1 does not get assembled.
8. Modify grub.conf entry with kernel flag: md=1,/dev/sda2,/dev/sdb2
no assembly of md1
assembly of md1
I think you need to put the devices in mdadm.conf. Here is what is in mine:
DEVICE /dev/sda6 /dev/sdb6 /dev/sda11 /dev/sdb11
ARRAY /dev/md0 level=0 devices=/dev/sda6,/dev/sdb6
ARRAY /dev/md1 level=1 devices=/dev/sda11,/dev/sdb11
Isn't mdadm.conf and/or /etc/raidtab unnecessary with persistent super-blocks?
So I just upgraded from FC6 to F8. The FC6 kernel auto detected my array (as the
constituent partitions are of type "fd") and auto-assembled it, as it's suppose
to. In fact, the FC6 kernel outputs this message when it startups (whether you
have md arrays or not):
md: Autodetecting RAID arrays.
However, with F8, md is no longer auto-detecting and auto-assembling anything.
The kernel doesn't output any message with regard to attempting to autodetect.
The FC6 kernel used to also mention that it was stopping md devices on shutdown,
no longer the case with F8 either.
Sure, I've added an ARRAY statement in /etc/mdadm.conf which triggers rc.sysinit
to execute "mdadm -A -s", and with the ARRAY entry in the config, mdadm succeeds
in assembling the array of course. However, this precludes the use of an md
array as rootfs (/), which is real shame.
What has changed with md between FC6 and F8? Is it a superblock type issue or
something? My superblock is of of version "00.90.03", which according to the
mdadm manpage is still the default (even though version-1 exists).
Sounds like you're not using an initrd to do the mdadm. Root RAID without an
initrd on Fedora is far from trivial :)
What about my response in comment#2? Isn't that true?
Auto-assemble has been removed from the kernel. The initrd should be assembling
all the arrays needed to boot the system. You could try to rebuild the initrd
(with the arrays assembled and mounted) and see if that fixes the problem, as
arrays added after the initrd was built won't be in its list.
Can I ask why this was removed from the kernel and placed into initrd? I
understand this strategy with drivers because almost every user system is
uniquely distinct, but mdraid is really common--and probably getting even more
so as time goes on.
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