Hi,

inspired from the performance test Mark did, I tried to compile my own one.
I have four OSD processes on one Node, each process has a Intel 710 SSD for its journal and 4 SAS Disk via an Lsi 9266-8i in Raid 0. If I test the SSD with fio they are quite fast and the w_wait time is quite low. But if I run rados bench on the cluster, the w_wait times for the journal devices are quite high (around 20-40ms).
I thought the SSD would be better, any ideas what happend here?

 -martin

Logs:

/dev/sd{c,d,e,f}
Intel SSD 710 200G

/dev/sd{g,h,i,j}
each 4 x SAS on LSI 9266-8i Raid 0

fio -name iops -rw=write -size=10G -iodepth 1 -filename /dev/sdc2 -ioengine libaio -direct 1 -bs 256k

Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
<- snip ->
sdc 0,00 0,00 0,00 809,20 0,00 202,30 512,00 0,96 1,19 0,00 1,19 1,18 95,84
<- snap ->



rados bench -p rbd 300 write -t 16

2012-10-15 17:53:17.058383min lat: 0.035382 max lat: 0.469604 avg lat: 0.189553
   sec Cur ops   started  finished  avg MB/s  cur MB/s  last lat   avg lat
   300      16     25329     25313   337.443       324  0.274815  0.189553
 Total time run:         300.169843
Total writes made:      25329
Write size:             4194304
Bandwidth (MB/sec):     337.529

Stddev Bandwidth:       25.1568
Max bandwidth (MB/sec): 372
Min bandwidth (MB/sec): 0
Average Latency:        0.189597
Stddev Latency:         0.0641609
Max latency:            0.469604
Min latency:            0.035382


during the rados bench test.

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
          20,38    0,00   16,20    8,87    0,00   54,55

Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await r_await w_await svctm %util sda 0,00 41,20 0,00 12,40 0,00 0,35 57,42 0,00 0,31 0,00 0,31 0,31 0,38 sdb 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 sdc 0,00 0,00 0,00 332,80 0,00 139,67 859,53 7,36 22,09 0,00 22,09 2,12 70,42 sdd 0,00 0,00 0,00 391,60 0,00 175,84 919,62 15,59 39,62 0,00 39,62 2,40 93,80 sde 0,00 0,00 0,00 342,00 0,00 147,39 882,59 8,54 24,89 0,00 24,89 2,18 74,58 sdf 0,00 0,00 0,00 362,20 0,00 162,72 920,05 15,35 42,50 0,00 42,50 2,60 94,20 sdg 0,00 0,00 0,00 522,00 0,00 139,20 546,13 0,28 0,54 0,00 0,54 0,10 5,26 sdh 0,00 0,00 0,00 672,00 0,00 179,20 546,13 9,67 14,42 0,00 14,42 0,61 41,18 sdi 0,00 0,00 0,00 555,00 0,00 148,00 546,13 0,32 0,57 0,00 0,57 0,10 5,46 sdj 0,00 0,00 0,00 582,00 0,00 155,20 546,13 0,51 0,87 0,00 0,87 0,12 6,96

100 seconds later

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
          22,92    0,00   19,57    9,25    0,00   48,25

Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await r_await w_await svctm %util sda 0,00 40,80 0,00 15,60 0,00 0,36 47,08 0,00 0,22 0,00 0,22 0,22 0,34 sdb 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 sdc 0,00 0,00 0,00 386,60 0,00 168,33 891,70 12,11 31,08 0,00 31,08 2,25 86,86 sdd 0,00 0,00 0,00 405,00 0,00 183,06 925,68 15,68 38,70 0,00 38,70 2,34 94,90 sde 0,00 0,00 0,00 411,00 0,00 185,06 922,15 15,58 38,09 0,00 38,09 2,33 95,92 sdf 0,00 0,00 0,00 387,00 0,00 168,33 890,79 12,19 31,48 0,00 31,48 2,26 87,48 sdg 0,00 0,00 0,00 646,20 0,00 171,22 542,64 0,42 0,65 0,00 0,65 0,10 6,70 sdh 0,00 85,60 0,40 797,00 0,01 192,97 495,65 10,95 13,73 32,50 13,72 0,55 44,22 sdi 0,00 0,00 0,00 678,20 0,00 180,01 543,59 0,45 0,67 0,00 0,67 0,10 6,76 sdj 0,00 0,00 0,00 639,00 0,00 169,61 543,61 0,36 0,57 0,00 0,57 0,10 6,32

 --admin-daemon /var/run/ceph/ceph-osd.1.asok perf dump
{"filestore":{"journal_queue_max_ops":500,"journal_queue_ops":0,"journal_ops":34653,"journal_queue_max_bytes":104857600,"journal_queue_bytes":0,"journal_bytes":86821481160,"journal_latency":{"avgcount":34653,"sum":3458.68},"journal_wr":19372,"journal_wr_bytes":{"avgcount":19372,"sum":87026655232},"op_queue_max_ops":500,"op_queue_ops":126,"ops":34653,"op_queue_max_bytes":104857600,"op_queue_bytes":167023,"bytes":86821143225,"apply_latency":{"avgcount":34527,"sum":605.768},"committing":0,"commitcycle":19,"commitcycle_interval":{"avgcount":19,"sum":572.674},"commitcycle_latency":{"avgcount":19,"sum":2.62279},"journal_full":0},"osd":{"opq":0,"op_wip":4,"op":15199,"op_in_bytes":36140461079,"op_out_bytes":0,"op_latency":{"avgcount":15199,"sum":1811.57},"op_r":0,"op_r_out_bytes":0,"op_r_latency":{"avgcount":0,"sum":0},"op_w":15199,"op_w_in_bytes":36140461079,"op_w_rlat":{"avgcount":15199,"sum":177.327},"op_w_latency":{"avgcount":15199,"sum":1811.57},"op_rw":0,"op_rw_in_bytes":0,"op!
_rw_out_
bytes":0,"op_rw_rlat":{"avgcount":0,"sum":0},"op_rw_latency":{"avgcount":0,"sum":0},"subop":19258,"subop_in_bytes":50617887978,"subop_latency":{"avgcount":19258,"sum":2110.84},"subop_w":0,"subop_w_in_bytes":50617887978,"subop_w_latency":{"avgcount":19258,"sum":2110.84},"subop_pull":0,"subop_pull_latency":{"avgcount":0,"sum":0},"subop_push":0,"subop_push_in_bytes":0,"subop_push_latency":{"avgcount":0,"sum":0},"pull":0,"push":0,"push_out_bytes":0,"push_in":0,"push_in_bytes":0,"recovery_ops":0,"loadavg":7.36,"buffer_bytes":0,"numpg":501,"numpg_primary":214,"numpg_replica":287,"numpg_stray":0,"heartbeat_to_peers":3,"heartbeat_from_peers":0,"map_messages":10,"map_message_epochs":34,"map_message_epoch_dups":28},"throttle-filestore_bytes":{"val":0,"max":104857600,"get":0,"get_sum":0,"get_or_fail_fail":0,"get_or_fail_success":0,"take":34653,"take_sum":86821481160,"put":19377,"put_sum":86821481160,"wait":{"avgcount":0,"sum":0}},"throttle-filestore_ops":{"val":0,"max":500,"get":0,"get!
_sum":0,"
get_or_fail_fail":0,"get_or_fail_success":0,"take":34653,"take_sum":34653,"put":19377,"put_sum":34653,"wait":{"avgcount":0,"sum":0}},"throttle-msgr_dispatch_throttler-client":{"val":0,"max":104857600,"get":13798,"get_sum":36132522860,"get_or_fail_fail":0,"get_or_fail_success":0,"take":0,"take_sum":0,"put":13798,"put_sum":36132522860,"wait":{"avgcount":0,"sum":0}},"throttle-msgr_dispatch_throttler-cluster":{"val":0,"max":104857600,"get":43047,"get_sum":50644298035,"get_or_fail_fail":0,"get_or_fail_success":0,"take":0,"take_sum":0,"put":43047,"put_sum":50644298035,"wait":{"avgcount":0,"sum":0}},"throttle-msgr_dispatch_throttler-hbclient":{"val":0,"max":104857600,"get":924,"get_sum":43428,"get_or_fail_fail":0,"get_or_fail_success":0,"take":0,"take_sum":0,"put":924,"put_sum":43428,"wait":{"avgcount":0,"sum":0}},"throttle-msgr_dispatch_throttler-hbserver":{"val":0,"max":104857600,"get":924,"get_sum":43428,"get_or_fail_fail":0,"get_or_fail_success":0,"take":0,"take_sum":0,"put":92!
4,"put_su
m":43428,"wait":{"avgcount":0,"sum":0}},"throttle-osd_client_bytes":{"val":0,"max":524288000,"get":13676,"get_sum":36132351923,"get_or_fail_fail":0,"get_or_fail_success":0,"take":0,"take_sum":0,"put":22290,"put_sum":36132351923,"wait":{"avgcount":0,"sum":0}}}

ceph.conf

[global]
      pid file = /var/run/$name.pid
       debug ms = 0
[mon]
      mon data = /data/mon.$id
       mon lease wiggle room = 1.0
       debug mon = 1
[mon.a]
      host = 01-00-25-90-79-cc-ba
      mon addr = 10.100.42.111:6789
[osd]
      osd data = /data/osd.$id
       debug osd = 1
       debug filestore = 1
       filestore max sync interval = 30
       filestore btrfs snap = true
       journal aio = true
[osd.0]
       host = 01-00-25-90-79-cc-ba
       osd journal = /dev/sdc1
       btrfs devs = /dev/sdg
       btrfs options = noatime,nodatacow,autodefrag
[osd.1]
       host = 01-00-25-90-79-cc-ba
       osd journal = /dev/sdd1
       btrfs devs = /dev/sdh
       btrfs options = noatime,nodatacow,autodefrag
[osd.2]
       host = 01-00-25-90-79-cc-ba
       osd journal = /dev/sde1
       btrfs devs = /dev/sdi
       btrfs options = noatime,nodatacow,autodefrag
[osd.3]
       host = 01-00-25-90-79-cc-ba
       osd journal = /dev/sdf1
       btrfs devs = /dev/sdj
       btrfs options = noatime,nodatacow,autodefrag
--
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