On Mon, Mar 13, 2017 at 10:35 AM, Florian Haas <florian@xxxxxxxxxxx> wrote: > On Sun, Mar 12, 2017 at 9:07 PM, Laszlo Budai <laszlo@xxxxxxxxxxxxxxxx> wrote: >> Hi Florian, >> >> thank you for your answer. >> >> We have already set the IO scheduler to cfq in order to be able to lower the >> priority of the scrub operations. >> My problem is that I've found different values set for the same parameter, >> and in each case they were doing it in order to achieve the same thing as we >> do. >> This is why I was asking for some more details about this parameter. Is the >> value 0 or 7 which will set the scrub to the lowest priority? I want my ceph >> cluster to be responsive for the client requests, and do the scrub in the >> background. >> >> I'm open to any ideas/suggestions which would help to improove the cluster's >> responsiveness during deep scrub operations. > > I'm sorry, I may have worded that in a manner that's easy to > misunderstand. I generally *never* suggest that people use CFQ on > reasonably decent I/O hardware, and thus have never come across any > need to set this specific ceph.conf parameter. OTOH, cfq *does* help our hammer clusters. deadline's default behaviour is to delay writes up to 5 seconds if the disk is busy reading -- which it is, of couse, while deep scrubbing. And deadline does not offer any sort of fairness between processes accessing the same disk (which is admittedly less of an issue in jewel). But back in hammer days it was nice to be able to make the disk threads only read while the disk was otherwise idle. -- Dan > > Maybe if you share your full ceph.conf and hardware details, I or > others on this list can offer more useful suggestions than tweaking > osd_disk_thread_ioprio_priority. > > Cheers, > Florian > _______________________________________________ > 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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