Hello all,
I have run into a sticky problem with a failed device in an md array,
and I asked about it on the linux raid mailing list, but since the
problem may not be md-specific, I am hoping to find some insight here.
(If you are on the MD list, and are seeing this twice, I humbly
apologize.)
The summary is that during a reshape of a raid6 on an up to date CentOS
6.3 box, one disk failed, and was marked as such in the array, but is
not allowing me to remove it:
# mdadm /dev/md127 --fail /dev/sdg
mdadm: set /dev/sdg faulty in /dev/md127
# mdadm /dev/md127 --remove /dev/sdg
mdadm: hot remove failed for /dev/sdg: Device or resource busy
And in dmesg, I get an error like so:
md: cannot remove active disk sdg from md127 ...
More details, including mdadm -D output and other diagnostics, are at
http://www.spinics.net/lists/raid/msg41928.html . As I note there, the
array seems fine otherwise, but is not currently in active use (so
perhaps my options are greater than if I wished to keep it deployed).
As the other messages in that thread show, I think I've already done
the ''obvious'' steps to try to remove the device from the array.
Checking things out further, I found that it may be that udev did not
completely remove the disk, even though the controller no longer
believes that the exported unit exists. (udevadm output is here:
http://www.spinics.net/lists/raid/msg41950.html ) So my hypothesis is
that if I can somehow force udev to drop the references to the disk
completely, perhaps I can remove sdg from the array and start a rebuild
with the spare already available. I found these docs for Fedora:
https://docs.fedoraproject.org/en-US/Fedora/14/html/Storage_Administration_Guide/removing_devices.html
But of course I can't do step 3, since md is refusing to give up sdg.
But sdg is already gone, so I really don't care about outstanding IO,
and it's a bit too late to worry about a 100% clean removal. So my
questions are, will step 7 actually clean up references to sdg, and how
likely is it that doing so would let me remove it from the array?
And finally, if the above is not a wise way to go, are there better
things to try? If other diagnostic output is desired please let me
know. Thanks!
--keith
--
kkeller@xxxxxxxxxxxxxxxxxxxxxxxxxx
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