Ok thanks but wouldn't it make sense to set the default to the same as rbd has? How is the value for rbd calculated? I've also seen that rbd has a different crushmap. What's the difference between crushmap 0 and 2? Stefan Am 19.06.2012 um 00:41 schrieb Dan Mick <dan.mick@xxxxxxxxxxx>: > Yes, this is almost certainly the problem. When you create the pool, you can specify a pg count; the default is 8, which is quite low. > The count can't currently be adjusted after pool-creation time (we're working on an enhancement for that). > > http://ceph.com/docs/master/control/ shows > > ceph osd pool create POOL [pg_num [pgp_num]] > > You'll want to set pg_num the same for similar pools in order to get for similar pool performance. > > I note also that you can get that field directlty: > $ ceph osd pool get rbd pg_num > PG_NUM: 448 > > I have a 'nova' pool that was created with "pool create": > > $ ceph osd pool get nova pg_num > PG_NUM: 8 > > > > On 06/18/2012 03:23 PM, Mark Nelson wrote: >> On 06/18/2012 04:39 PM, Stefan Priebe wrote: >>> Hello list, >>> >>> i'm getting these rbd bench values for pool rbd. They're high and >>> constant. >>> ----------------------------- RBD pool >>> # rados -p rbd bench 30 write -t 16 >>> Maintaining 16 concurrent writes of 4194304 bytes for at least 30 >>> seconds. >>> sec Cur ops started finished avg MB/s cur MB/s last lat avg lat >>> 0 0 0 0 0 0 - 0 >>> 1 16 274 258 1031.77 1032 0.043758 0.0602236 >>> 2 16 549 533 1065.82 1100 0.072168 0.0590944 >>> 3 16 825 809 1078.5 1104 0.040162 0.058682 >>> 4 16 1103 1087 1086.84 1112 0.052508 0.0584277 >>> 5 16 1385 1369 1095.04 1128 0.060233 0.0581288 >>> 6 16 1654 1638 1091.85 1076 0.050697 0.0583385 >>> 7 16 1939 1923 1098.71 1140 0.063716 0.057964 >>> 8 16 2219 2203 1101.35 1120 0.055435 0.0579105 >>> 9 16 2497 2481 1102.52 1112 0.060413 0.0578282 >>> 10 16 2773 2757 1102.66 1104 0.051134 0.0578561 >>> 11 16 3049 3033 1102.77 1104 0.057742 0.0578803 >>> 12 16 3326 3310 1103.19 1108 0.053769 0.0578627 >>> 13 16 3604 3588 1103.86 1112 0.064574 0.0578453 >>> 14 16 3883 3867 1104.72 1116 0.056524 0.0578018 >>> 15 16 4162 4146 1105.46 1116 0.054581 0.0577626 >>> 16 16 4440 4424 1105.86 1112 0.079015 0.057758 >>> 17 16 4725 4709 1107.86 1140 0.043511 0.0576647 >>> 18 16 5007 4991 1108.97 1128 0.053005 0.0576147 >>> 19 16 5292 5276 1110.6 1140 0.069004 0.057538 >>> 2012-06-18 23:36:19.124472min lat: 0.028568 max lat: 0.201941 avg lat: >>> 0.0574953 >>> sec Cur ops started finished avg MB/s cur MB/s last lat avg lat >>> 20 16 5574 5558 1111.46 1128 0.048482 0.0574953 >>> 21 16 5861 5845 1113.18 1148 0.051923 0.0574146 >>> 22 16 6147 6131 1114.58 1144 0.04461 0.0573461 >>> 23 16 6438 6422 1116.72 1164 0.050383 0.0572406 >>> 24 16 6724 6708 1117.85 1144 0.067827 0.0571864 >>> 25 16 7008 6992 1118.57 1136 0.049128 0.057147 >>> 26 16 7296 7280 1119.85 1152 0.050331 0.0570879 >>> 27 16 7573 7557 1119.4 1108 0.052711 0.0571132 >>> 28 16 7858 7842 1120.13 1140 0.056369 0.0570764 >>> 29 16 8143 8127 1120.81 1140 0.046558 0.0570438 >>> 30 16 8431 8415 1121.85 1152 0.049958 0.0569942 >>> Total time run: 30.045481 >>> Total writes made: 8431 >>> Write size: 4194304 >>> Bandwidth (MB/sec): 1122.432 >>> >>> Stddev Bandwidth: 26.0451 >>> Max bandwidth (MB/sec): 1164 >>> Min bandwidth (MB/sec): 1032 >>> Average Latency: 0.0570069 >>> Stddev Latency: 0.0128039 >>> Max latency: 0.235536 >>> Min latency: 0.028568 >>> ----------------------------- >>> >>> I created then a custom pool called kvmpool. >>> >>> ~# ceph osd pool create kvmpool >>> pool 'kvmpool' created >>> >>> But with this one i get slow and jumping values: >>> -------------------------------- kvmpool >>> ~# rados -p kvmpool bench 30 write -t 16 >>> Maintaining 16 concurrent writes of 4194304 bytes for at least 30 >>> seconds. >>> sec Cur ops started finished avg MB/s cur MB/s last lat avg lat >>> 0 0 0 0 0 0 - 0 >>> 1 16 231 215 859.863 860 0.204867 0.069195 >>> 2 16 393 377 753.899 648 0.049444 0.0811933 >>> 3 16 535 519 691.908 568 0.232365 0.0899074 >>> 4 16 634 618 617.913 396 0.032758 0.0963399 >>> 5 16 806 790 631.913 688 0.075811 0.099529 >>> 6 16 948 932 621.249 568 0.156988 0.10179 >>> 7 16 1086 1070 611.348 552 0.036177 0.102064 >>> 8 16 1206 1190 594.922 480 0.028491 0.105235 >>> 9 16 1336 1320 586.589 520 0.041009 0.108735 >>> 10 16 1512 1496 598.32 704 0.258165 0.105086 >>> 11 16 1666 1650 599.921 616 0.040967 0.106146 >>> 12 15 1825 1810 603.255 640 0.198851 0.105463 >>> 13 16 1925 1909 587.309 396 0.042577 0.108449 >>> 14 16 2135 2119 605.352 840 0.035767 0.105219 >>> 15 16 2272 2256 601.523 548 0.246136 0.105357 >>> 16 16 2426 2410 602.424 616 0.19881 0.105692 >>> 17 16 2529 2513 591.22 412 0.031322 0.105463 >>> 18 16 2696 2680 595.48 668 0.028081 0.106749 >>> 19 16 2878 2862 602.449 728 0.044929 0.105856 >>> 2012-06-18 23:38:45.566094min lat: 0.023295 max lat: 0.763797 avg lat: >>> 0.105597 >>> sec Cur ops started finished avg MB/s cur MB/s last lat avg lat >>> 20 16 3041 3025 604.921 652 0.036028 0.105597 >>> 21 16 3182 3166 602.964 564 0.035072 0.104915 >>> 22 16 3349 3333 605.916 668 0.030493 0.105304 >>> 23 16 3512 3496 607.917 652 0.030523 0.10479 >>> 24 16 3668 3652 608.584 624 0.232933 0.10475 >>> 25 16 3821 3805 608.717 612 0.029881 0.104513 >>> 26 16 3963 3947 607.148 568 0.050244 0.10531 >>> 27 16 4112 4096 606.733 596 0.259069 0.105008 >>> 28 16 4261 4245 606.347 596 0.211877 0.105215 >>> 29 16 4437 4421 609.712 704 0.02802 0.104613 >>> 30 16 4566 4550 606.586 516 0.047076 0.105111 >>> Total time run: 30.062141 >>> Total writes made: 4566 >>> Write size: 4194304 >>> Bandwidth (MB/sec): 607.542 >>> >>> Stddev Bandwidth: 109.112 >>> Max bandwidth (MB/sec): 860 >>> Min bandwidth (MB/sec): 396 >>> Average Latency: 0.10532 >>> Stddev Latency: 0.108369 >>> Max latency: 0.763797 >>> Min latency: 0.023295 >>> -------------------------------- >>> >>> Why do these pools differ? Where is the difference? >>> >>> Stefan >> >> Are the number of placement groups the same for each pool? >> >> try running "ceph osd dump -o - | grep <pool>" and looking for the >> pg_num value. >> >> Mark >> >> -- >> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
