I've just made the same change ( 4 and 40 for now) on my cluster which is a similar size to yours. I didn't see any merging happening, although most of the directory's I looked at had more files in than the new merge threshold, so I guess this is to be expected I'm currently splitting my PG's from 1024 to 2048 to see if that helps to bring things back into order. > -----Original Message----- > From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of > Wang, Warren > Sent: 04 September 2015 01:21 > To: Mark Nelson <mnelson@xxxxxxxxxx>; Ben Hines <bhines@xxxxxxxxx> > Cc: ceph-users <ceph-users@xxxxxxxxxxxxxx> > Subject: Re: Ceph performance, empty vs part full > > I'm about to change it on a big cluster too. It totals around 30 million, so I'm a > bit nervous on changing it. As far as I understood, it would indeed move > them around, if you can get underneath the threshold, but it may be hard to > do. Two more settings that I highly recommend changing on a big prod > cluster. I'm in favor of bumping these two up in the defaults. > > Warren > > -----Original Message----- > From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of > Mark Nelson > Sent: Thursday, September 03, 2015 6:04 PM > To: Ben Hines <bhines@xxxxxxxxx> > Cc: ceph-users <ceph-users@xxxxxxxxxxxxxx> > Subject: Re: Ceph performance, empty vs part full > > Hrm, I think it will follow the merge/split rules if it's out of whack given the > new settings, but I don't know that I've ever tested it on an existing cluster to > see that it actually happens. I guess let it sit for a while and then check the > OSD PG directories to see if the object counts make sense given the new > settings? :D > > Mark > > On 09/03/2015 04:31 PM, Ben Hines wrote: > > Hey Mark, > > > > I've just tweaked these filestore settings for my cluster -- after > > changing this, is there a way to make ceph move existing objects > > around to new filestore locations, or will this only apply to newly > > created objects? (i would assume the latter..) > > > > thanks, > > > > -Ben > > > > On Wed, Jul 8, 2015 at 6:39 AM, Mark Nelson <mnelson@xxxxxxxxxx> > wrote: > >> Basically for each PG, there's a directory tree where only a certain > >> number of objects are allowed in a given directory before it splits > >> into new branches/leaves. The problem is that this has a fair amount > >> of overhead and also there's extra associated dentry lookups to get at any > given object. > >> > >> You may want to try something like: > >> > >> "filestore merge threshold = 40" > >> "filestore split multiple = 8" > >> > >> This will dramatically increase the number of objects per directory > allowed. > >> > >> Another thing you may want to try is telling the kernel to greatly > >> favor retaining dentries and inodes in cache: > >> > >> echo 1 | sudo tee /proc/sys/vm/vfs_cache_pressure > >> > >> Mark > >> > >> > >> On 07/08/2015 08:13 AM, MATHIAS, Bryn (Bryn) wrote: > >>> > >>> If I create a new pool it is generally fast for a short amount of time. > >>> Not as fast as if I had a blank cluster, but close to. > >>> > >>> Bryn > >>>> > >>>> On 8 Jul 2015, at 13:55, Gregory Farnum <greg@xxxxxxxxxxx> wrote: > >>>> > >>>> I think you're probably running into the internal PG/collection > >>>> splitting here; try searching for those terms and seeing what your > >>>> OSD folder structures look like. You could test by creating a new > >>>> pool and seeing if it's faster or slower than the one you've already filled > up. > >>>> -Greg > >>>> > >>>> On Wed, Jul 8, 2015 at 1:25 PM, MATHIAS, Bryn (Bryn) > >>>> <bryn.mathias@xxxxxxxxxxxxxxxxxx> wrote: > >>>>> > >>>>> Hi All, > >>>>> > >>>>> > >>>>> I’m perf testing a cluster again, > >>>>> This time I have re-built the cluster and am filling it for testing. > >>>>> > >>>>> on a 10 min run I get the following results from 5 load > >>>>> generators, each writing though 7 iocontexts, with a queue depth of > 50 async writes. > >>>>> > >>>>> > >>>>> Gen1 > >>>>> Percentile 100 = 0.729775905609 > >>>>> Max latencies = 0.729775905609, Min = 0.0320818424225, mean = > >>>>> 0.0750389684542 > >>>>> Total objects writen = 113088 in time 604.259738207s gives > >>>>> 187.151307376/s (748.605229503 MB/s) > >>>>> > >>>>> Gen2 > >>>>> Percentile 100 = 0.735981941223 > >>>>> Max latencies = 0.735981941223, Min = 0.0340068340302, mean = > >>>>> 0.0745198070711 > >>>>> Total objects writen = 113822 in time 604.437897921s gives > >>>>> 188.310495407/s (753.241981627 MB/s) > >>>>> > >>>>> Gen3 > >>>>> Percentile 100 = 0.828994989395 > >>>>> Max latencies = 0.828994989395, Min = 0.0349340438843, mean = > >>>>> 0.0745455575197 > >>>>> Total objects writen = 113670 in time 604.352181911s gives > >>>>> 188.085694736/s (752.342778944 MB/s) > >>>>> > >>>>> Gen4 > >>>>> Percentile 100 = 1.06834602356 > >>>>> Max latencies = 1.06834602356, Min = 0.0333499908447, mean = > >>>>> 0.0752239764659 > >>>>> Total objects writen = 112744 in time 604.408732891s gives > >>>>> 186.536020849/s (746.144083397 MB/s) > >>>>> > >>>>> Gen5 > >>>>> Percentile 100 = 0.609658002853 > >>>>> Max latencies = 0.609658002853, Min = 0.032968044281, mean = > >>>>> 0.0744482759499 > >>>>> Total objects writen = 113918 in time 604.671534061s gives > >>>>> 188.396498897/s (753.585995589 MB/s) > >>>>> > >>>>> example ceph -w output: > >>>>> 2015-07-07 15:50:16.507084 mon.0 [INF] pgmap v1077: 2880 pgs: 2880 > >>>>> active+clean; 1996 GB data, 2515 GB used, 346 TB / 348 TB avail; > >>>>> active+2185 MB/s > >>>>> wr, 572 op/s > >>>>> > >>>>> > >>>>> However when the cluster gets over 20% full I see the following > >>>>> results, this gets worse as the cluster fills up: > >>>>> > >>>>> Gen1 > >>>>> Percentile 100 = 6.71176099777 > >>>>> Max latencies = 6.71176099777, Min = 0.0358741283417, mean = > >>>>> 0.161760483485 > >>>>> Total objects writen = 52196 in time 604.488474131s gives > >>>>> 86.347386648/s > >>>>> (345.389546592 MB/s) > >>>>> > >>>>> Gen2 > >>>>> Max latencies = 4.09169006348, Min = 0.0357890129089, mean = > >>>>> 0.163243938477 > >>>>> Total objects writen = 51702 in time 604.036739111s gives > >>>>> 85.5941313704/s (342.376525482 MB/s) > >>>>> > >>>>> Gen3 > >>>>> Percentile 100 = 7.32526683807 > >>>>> Max latencies = 7.32526683807, Min = 0.0366668701172, mean = > >>>>> 0.163992217926 > >>>>> Total objects writen = 51476 in time 604.684302092s gives > >>>>> 85.1287189397/s (340.514875759 MB/s) > >>>>> > >>>>> Gen4 > >>>>> Percentile 100 = 7.56094503403 > >>>>> Max latencies = 7.56094503403, Min = 0.0355761051178, mean = > >>>>> 0.162109421231 > >>>>> Total objects writen = 52092 in time 604.769910812s gives > >>>>> 86.1352376642/s (344.540950657 MB/s) > >>>>> > >>>>> > >>>>> Gen5 > >>>>> Percentile 100 = 6.99595499039 > >>>>> Max latencies = 6.99595499039, Min = 0.0364680290222, mean = > >>>>> 0.163651215426 > >>>>> Total objects writen = 51566 in time 604.061977148s gives > >>>>> 85.3654127404/s (341.461650961 MB/s) > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> Cluster details: > >>>>> 5*HPDL380’s with 13*6Tb OSD’s > >>>>> 128Gb Ram > >>>>> 2*intel 2620v3 > >>>>> 10 Gbit Ceph public network > >>>>> 10 Gbit Ceph private network > >>>>> > >>>>> Load generators connected via a 20Gbit bond to the ceph public > network. > >>>>> > >>>>> > >>>>> Is this likely to be something happening to the journals? > >>>>> > >>>>> Or is there something else going on. > >>>>> > >>>>> I have run FIO and iperf tests and the disk and network > >>>>> performance is very high. > >>>>> > >>>>> > >>>>> Kind Regards, > >>>>> Bryn Mathias > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> _______________________________________________ > >>>>> 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 > >>> > >> _______________________________________________ > >> 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 > _______________________________________________ > 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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