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
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