On Wednesday 09 May 2007 15:14:50 martin f krafft wrote:

also sprach Bernd Schubert [off-list ref] [2007.05.09.1417 +0200]:

quoted

Problem-1) When the disk fails, udev will remove it from /dev.
Unfortunately this will make it impossible to remove the disk or its
partitions from /dev/mdX device, since mdadm tries to read the device
fail and will abort if this file is not there.

Please also see http://bugs.debian.org/416512. It would be nice if
you could keep 416512@bugs.debian.org on CC.

mdadm upstream knows of the problem. See the bug log.

Ah, so Goswin already wrote a bug report :) Actually Goswin first did run into 
this problem here while doing some internal tests, but today we have it on a 
customer system.

Neil Brown [off-list ref] [2007.04.02.0953 +0200]:

Hmmm... this is somewhat awkward.  You could argue that udev should be
taught to remove the device from the array before removing the device
from /dev.  But I'm not convinced that you always want to 'fail' the
device.   It is possible in this case that the array is quiescent and
you might like to shut it down without registering a device failure...

Hmm, the the kernel advised hotplug to remove the device from /dev, but you 
don't want to remove it from md? Do you have an example for that case?

It is still possible to fail and remove the device by
writing "faulty" and then "remove" to
 /sys/block/mdX/md/dev-YYY/state

Maybe an mdadm command that will do that for a given device, or for
all components of a given array if the 'dev' link is 'broken', or even
for all devices for all array.

  mdadm --fail-unplugged --scan
or
  mdadm --fail-unplugged /dev/md3

Ok, so one could run this as cron script. Neil, may I ask if you already 
started to work on this? Since we have the problem on a customer system, we 
should fix it ASAP, but at least within the next 2 or 3 weeks. If you didn't 
start work on it yet, I will do...


Thanks,
Bernd


-- 
Bernd Schubert
Q-Leap Networks GmbH