On Tue, Mar 02, 2010 at 02:04:26PM -0600, Csaba Biegl wrote:
1) On machine #1 mdadm release versions 3.0.3 and 3.1.1 both fail to start
mdmon, therefore assembled RAID is read only. Checked out latest git
version of mdadm, runs array fine. After this I did not even bother with
release versions of mdadm on machine #2.
yes many issues related to imsm are fixed in git and scheduled for 3.1.2
2) On machine #2 mdadm assembles the DDF BIOS created array fine, however
upon shutdown it somehow updates the metadata in a way that the BIOS does
not recognize the arrays any more. But booting Linux again -- of course not
from the freshly trashed RAID :-( -- the array can be re-assembled using
mdadm.
are you sure you dont kill mdmon process at shutdown time?
3) The latest git version of mdmon has some command line processing bugs
that will crash the program if no container is given on the command line
(i.e. "mdmon --all --takeover", etc..). Patch attached.
I sent a different patch to address the same problems a couple of days
ago.
4) The static linked version of mdmon crashes in the forked daemon process.
According to "gdb mdmon core", the crash is in one of the signal handlers
("wake_me") which gets called with an invalid stack pointer. To me it looks
like this is not mdmon's problem but rather a brain-dead static libc. Did
not try other environments, so I do not know whether this is Slackware
and/or 64 bit specific.
if you could do more tests or send in a bt it would be appreciated.
Question:
I chose a startup/initrd approach somewhat different than what is suggested
in the documentation. It is based on the fact that the RAID array can be
assembled in read-only mode just by "mdadm" without an available "mdmon".
Relevant steps from the initrd's init script:
mdadm -Es > /etc/mdadm.conf
this is unneeded
mdadm -As
mount -r /dev/mdXpY /mnt
mount -n -t tmpfs initrw /mnt/lib/init/rw
mkdir -p /mnt/lib/init/rw/mdadm
for dev in /dev/md/ddf* /dev/md/imsm*; do mdmon $dev; done
that's what --all is for
switch_root /mnt /sbin/init
With the following links/files in place on the initrd:
/sbin/mdadm # statically linked
/sbin/mdmon -> /mnt/sbin/mdmon
/lib64/*.so -> /mnt/lib64/*.so # libraries needed by the
dynamically linked mdmon
/var/run/mdadm -> /mnt/init/rw/mdadm
/init/rw/mdadm -> /mnt/init/rw/mdadm
And the final system also has this:
/var/run/mdadm -> /lib/init/rw/mdadm
So this approach allows me to run the final system's copy of mdmon, without
ever having to use the '--takeover' stuff. And the mdmon "status" files are
always in the same place. And /var can be unmounted during shutdown.
Anything wrong with this? So far working fine for me...
the reason for the takeover is not moving the socket from /lib/init/rw
to /var.
mdmon running from initramfs has the text sections mapped to files on
the ram disk. we kill it and restart it in order to release these memory
areas and free the memory allocated by initramfs.
L.
--
Luca Berra -- bluca@xxxxxxxxxx
Communication Media & Services S.r.l.
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