Hi Peter, yes just restart the OSD for the setting to take effect.
From: ceph-users [mailto:ceph-users-boun...@lists.ceph.com] On Behalf Of Peter Kerdisle Sent: 10 May 2016 19:06 To: Nick Fisk <n...@fisk.me.uk> Cc: ceph-users@lists.ceph.com Subject: Re: [ceph-users] Erasure pool performance expectations Thanks Nick. I added it to my ceph.conf. I'm guessing this is an OSD setting and therefor I should restart my OSDs is that correct? On Tue, May 10, 2016 at 3:48 PM, Nick Fisk <n...@fisk.me.uk <mailto:n...@fisk.me.uk> > wrote: > -----Original Message----- > From: ceph-users [mailto:ceph-users-boun...@lists.ceph.com > <mailto:ceph-users-boun...@lists.ceph.com> ] On Behalf Of > Peter Kerdisle > Sent: 10 May 2016 14:37 > Cc: ceph-users@lists.ceph.com <mailto:ceph-users@lists.ceph.com> > Subject: Re: [ceph-users] Erasure pool performance expectations > > To answer my own question it seems that you can change settings on the fly > using > > ceph tell osd.* injectargs '--osd_tier_promote_max_bytes_sec 5242880' > osd.0: osd_tier_promote_max_bytes_sec = '5242880' (unchangeable) > > However the response seems to imply I can't change this setting. Is there an > other way to change these settings? Sorry Peter, I missed your last email. You can also specify that setting in the ceph.conf, ie I have in mine osd_tier_promote_max_bytes_sec = 4000000 > > > On Sun, May 8, 2016 at 2:37 PM, Peter Kerdisle <peter.kerdi...@gmail.com > <mailto:peter.kerdi...@gmail.com> > > wrote: > 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 > <mailto: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 <mailto:mnel...@redhat.com> > > To: ceph-users@lists.ceph.com <mailto:ceph-users@lists.ceph.com> > Subject: Re: [ceph-users] Erasure pool performance expectations > Message-ID: <df3de049-a7f9-7f86-3ed3-47079e401...@redhat.com > <mailto: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 > >
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