Hi Jason,
I've tried to do enable the lttng tracing but no success.
I have done the steps from [1] and [2] but nothing happened ...
It's difficult to catch the event to dump the objecter requests because when we observe the event, this is already past away.
Kind regards,
Laszlo
On 04.04.2017 17:06, Jason Dillaman wrote:
Couple options:
1) you can enable LTTng-UST tracing [1][2] against your VM for an
extremely light-weight way to track IO latencies.
2) you can enable "debug rbd = 20" and grep through the logs for
matching "AioCompletion.*(set_request_count|finalize)" log entries
3) use the asok file during one of these events to dump the objecter requests
[1] http://docs.ceph.com/docs/jewel/rbd/rbd-replay/
[2] http://tracker.ceph.com/issues/14629
On Tue, Apr 4, 2017 at 7:36 AM, Laszlo Budai <laszlo@xxxxxxxxxxxxxxxx> wrote:
Hello cephers,
I have a situation where from time to time the write operation to the seph
storage hangs for 3-5 seconds. For testing we have a simple line like:
while sleep 1; date >> logfile; done &
with this we can see that rarely there are 3 seconds or more differences
between the consecutive outputs of date.
Initially we have suspected the deep scrub and we have tuned its parameters,
so right now I'm confident that the reason is something different than the
deep scrubbing.
I would like to know if any of you has encountered a similar situation, and
what was the solution for it.
I am suspecting the network between the compute nodes and the storage, but I
need to prove this. I am thinking on enabling client side logging for
librbd, but I see there are many subsystems where the logging can be
enabled. Can anyone tell me which subsystem should I log, and at which level
to be able to see whether the network is causing write issues?
We're using ceph 0.94.10.
Thank you,
Laszlo
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