> -----Original Message----- > From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of > MATHIAS, Bryn (Bryn) > Sent: 21 June 2015 20:52 > To: Nick Fisk > Cc: ceph-users@xxxxxxxxxxxxxx > Subject: Re: [COMMERCIAL] Ceph EC pool performance > benchmarking, highlatencies. > > > >> > > > > Just out of interest do any of your journals or disks look like they are > getting maxed out? > > > > Your latency breakdown seems to indicate that the bulk of requests are > being serviced in reasonable time, but around 5% (or less) are taking > excessively long for some reason. > > > > I'm wondering if something is causing a backlog on the journals? > > > > In regards to your query about the delay between the applied and done I > wonder if this is just showing the time that the data was sitting in journal > waiting to be flushed? Once the write has been committed by the journal, > from a clients perspective the write is complete. > > Any thing in particular I should be looking at here? Not really, I was just a bit suspicious if you were hitting some sort of write back throttling on the journal, or if when the disks sync, the journals are getting bogged down. This might cause peaks which would delay only a couple of operations at a time. If you look at the disks with iostat (or whatever tool you use) do you see them get very busy with high wait times for large periods of time? > > I have the collectd ceph plugin running and am watching the max journal > latency and it doesn’t go very high. > Journals exist on the OSD disks rather than on separate disks. > > And I agree, most of the latencies are pretty low, unless I start hitting the > cluster with all 7 load generators in which case I get a lot of very high > latencies. > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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