Hey guys, I noticed the merge request that fixes the switch around here https://github.com/ceph/ceph/pull/8912
I had two questions: - Does this effect my performance in any way? Could it explain the slow requests I keep having? - Can I modify these settings manually myself on my cluster? Thanks, Peter On Fri, May 6, 2016 at 9:58 AM, Peter Kerdisle <peter.kerdi...@gmail.com> wrote: > Hey Mark, > > Sorry I missed your message as I'm only subscribed to daily digests. > > >> Date: Tue, 3 May 2016 09:05:02 -0500 >> From: Mark Nelson <mnel...@redhat.com> >> To: ceph-users@lists.ceph.com >> Subject: Re: [ceph-users] Erasure pool performance expectations >> Message-ID: <df3de049-a7f9-7f86-3ed3-47079e401...@redhat.com> >> Content-Type: text/plain; charset=windows-1252; format=flowed >> In addition to what nick said, it's really valuable to watch your cache >> tier write behavior during heavy IO. One thing I noticed is you said >> you have 2 SSDs for journals and 7 SSDs for data. > > > I thought the hardware recommendations were 1 journal disk per 3 or 4 data > disks but I think I might have misunderstood it. Looking at my journal > read/writes they seem to be ok though: > https://www.dropbox.com/s/er7bei4idd56g4d/Screenshot%202016-05-06%2009.55.30.png?dl=0 > > However I started running into a lot of slow requests (made a separate > thread for those: Diagnosing slow requests) and now I'm hoping these > could be related to my journaling setup. > > >> If they are all of >> the same type, you're likely bottlenecked by the journal SSDs for >> writes, which compounded with the heavy promotions is going to really >> hold you back. >> What you really want: >> 1) (assuming filestore) equal large write throughput between the >> journals and data disks. > > How would one achieve that? > >> >> 2) promotions to be limited by some reasonable fraction of the cache >> tier and/or network throughput (say 70%). This is why the >> user-configurable promotion throttles were added in jewel. > > Are these already in the docs somewhere? > >> >> 3) The cache tier to fill up quickly when empty but change slowly once >> it's full (ie limiting promotions and evictions). No real way to do >> this yet. >> Mark > > > Thanks for your thoughts. > > Peter > >
_______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
