Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Sat, Dec 13, 2008 at 12:57:59PM -0800, Nolan wrote:
> On Fri, 2008-12-13 at 17:11 +0100, Lars Ellenberg wrote:
> > appart from running many processes doing direct io to the same
> > block, there is not much I can think of that may produce these
> > concurrent writes.
>
> I am doing direct IO (via kvm's cache=off option).
>
> There is only the one process, but I believe it simulates AIO using
> glibc's thread-based AIO implementation.
>
> Since the guest (debian etch) is using SCSI TCQ, it could in theory
> write the same block many times. No idea why it would do that though.
>
> I've also no idea why running a verify would trigger it, if that is
> something more than mere coincidence.
either "coincidence", or because of the added IO load (read the whole
disk and checksum it) changes the timing. this has nothing to do with
the "hanging" drbd resource, though.
> > can you do the ps -eo | grep magic on the other node as well please?
>
> # ps -eo pid,state,wchan:30,cmd | grep -e drbd -e D
> PID S WCHAN CMD
> 3002 S select /usr/local/bin/qemu-system-x86_64
> -m 512 -drive file=/dev/drbd23,if=scsi,cache=off,boot=on -drive
> if=ide,index=2,media=cdrom -usbdevice tablet -name root_vm_0 -net
> nic,macaddr=xx:xx:xx:xx:xx:xx,model=virtio -net tap -monitor
> unix:/tmp/VM_root_vm_0,server,nowait -tdf -daemonize -vnc :0,password
> 5261 S drbd_wait_peer_seq [drbd24_receiver]
^^^^^^^^^^^^^^^^^^
there.
that is an interessting hint.
this has been fixed in 8.2.7.
as a workaround, you can use e.g. iptables to disconnect/reconnect,
but chances are that an online verify will again get stuck in your setup.
just make sure that you add the drbd-8.2.7 hotfix for the online verify
as well, so either use the drbd 8.2.7 tarball
plus this patch:
http://git.drbd.org/drbd-8.2.git/?p=drbd-8.2.git;a=commitdiff;h=1174410#patch1
or even better, use drbd-8.2 HEAD, there:
http://git.drbd.org/drbd-8.2.git/
we are confident that we will release a fine 8.3.0 this week,
which supersedes the 8.2 series.
--
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com
DRBD® and LINBIT® are registered trademarks of LINBIT, Austria.
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