Thank You Mark , please see my response below.
On Wed, Sep 2, 2015 at 5:23 PM, Mark Nelson <mnelson@xxxxxxxxxx> wrote:
On 09/02/2015 08:51 AM, Vickey Singh wrote:
Hello Ceph Experts
I have a strange problem , when i am reading or writing to Ceph pool ,
its not writing properly. Please notice Cur MB/s which is going up and down
--- Ceph Hammer 0.94.2
-- CentOS 6, 2.6
-- Ceph cluster is healthy
You might find that CentOS7 gives you better performance. In some cases we were seeing nearly 2X.
Wooo 2X , i would definitely plan for upgrade. Thanks
One interesting thing is when every i start rados bench command for read
or write CPU Idle % goes down ~10 and System load is increasing like
anything.
Hardware
HpSL4540
Please make sure the controller is on the newest firmware. There used to be a bug that would cause sequential write performance to bottleneck when writeback cache was enabled on the RAID controller.
Last month i have upgraded the firmwares for this hardware , so i hope they are up to date.
32Core CPU
196G Memory
10G Network
Be sure to check the network too. We've seen a lot of cases where folks have been burned by one of the NICs acting funky.
At a first view , Interface looks good and they are pushing data nicely ( what ever they are getting )
<http://10.100.50.1:6789/0,s02=10.100.50.2:6789/0,s03=1>
I don't think hardware is a problem.
Please give me clues / pointers , how should i troubleshoot this problem.
# rados bench -p glance-test 60 write
Maintaining 16 concurrent writes of 4194304 bytes for up to 60 seconds
or 0 objects
Object prefix: benchmark_data_pouta-s01.pouta.csc.fi_2173350
sec Cur ops started finished avg MB/s cur MB/s last lat avg lat
0 0 0 0 0 0 - 0
1 16 20 4 15.99 16 0.12308 0.10001
2 16 37 21 41.9841 68 1.79104 0.827021
3 16 68 52 69.3122 124 0.084304 0.854829
4 16 114 98 97.9746 184 0.12285 0.614507
5 16 188 172 137.568 296 0.210669 0.449784
6 16 248 232 154.634 240 0.090418 0.390647
7 16 305 289 165.11 228 0.069769 0.347957
8 16 331 315 157.471 104 0.026247 0.3345
9 16 361 345 153.306 120 0.082861 0.320711
10 16 380 364 145.575 76 0.027964 0.310004
11 16 393 377 137.067 52 3.73332 0.393318
12 16 448 432 143.971 220 0.334664 0.415606
13 16 476 460 141.508 112 0.271096 0.406574
14 16 497 481 137.399 84 0.257794 0.412006
15 16 507 491 130.906 40 1.49351 0.428057
16 16 529 513 115.042 88 0.399384 0.48009
17 16 533 517 94.6286 16 5.50641 0.507804
18 16 537 521 83.405 16 4.42682 0.549951
19 16 538 522 80.349 4 11.2052 0.570363
2015-09-02 09:26:18.398641min lat: 0.023851 max lat: 11.2052 avg lat:
0.570363
sec Cur ops started finished avg MB/s cur MB/s last lat avg lat
20 16 538 522 77.3611 0 - 0.570363
21 16 540 524 74.8825 4 8.88847 0.591767
22 16 542 526 72.5748 8 1.41627 0.593555
23 16 543 527 70.2873 4 8.0856 0.607771
24 16 555 539 69.5674 48 0.145199 0.781685
25 16 560 544 68.0177 20 1.4342 0.787017
26 16 564 548 66.4241 16 0.451905 0.78765
27 16 566 550 64.7055 8 0.611129 0.787898
28 16 570 554 63.3138 16 2.51086 0.797067
29 16 570 554 61.5549 0 - 0.797067
30 16 572 556 60.1071 4 7.71382 0.830697
31 16 577 561 59.0515 20 23.3501 0.916368
32 16 590 574 58.8705 52 0.336684 0.956958
33 16 591 575 57.4986 4 1.92811 0.958647
34 16 591 575 56.0961 0 - 0.958647
35 16 591 575 54.7603 0 - 0.958647
36 16 597 581 54.0447 8 0.187351 1.00313
37 16 625 609 52.8394 112 2.12256 1.09256
38 16 631 615 52.227 24 1.57413 1.10206
39 16 638 622 51.7232 28 4.41663 1.15086
2015-09-02 09:26:40.510623min lat: 0.023851 max lat: 27.6704 avg lat:
1.15657
sec Cur ops started finished avg MB/s cur MB/s last lat avg lat
40 16 652 636 51.8102 56 0.113345 1.15657
41 16 682 666 53.1443 120 0.041251 1.17813
42 16 685 669 52.3395 12 0.501285 1.17421
43 15 690 675 51.7955 24 2.26605 1.18357
44 16 728 712 53.6062 148 0.589826 1.17478
45 16 728 712 52.6158 0 - 1.17478
46 16 728 712 51.6613 0 - 1.17478
47 16 728 712 50.7407 0 - 1.17478
48 16 772 756 52.9332 44 0.234811 1.1946
49 16 835 819 56.3577 252 5.67087 1.12063
50 16 890 874 59.1252 220 0.230806 1.06778
51 16 896 880 58.5409 24 0.382471 1.06121
52 16 896 880 57.5832 0 - 1.06121
53 16 896 880 56.6562 0 - 1.06121
54 16 896 880 55.7587 0 - 1.06121
55 16 897 881 54.9515 1 4.88333 1.06554
56 16 897 881 54.1077 0 - 1.06554
57 16 897 881 53.2894 0 - 1.06554
58 16 897 881 51.9335 0 - 1.06554
59 16 897 881 51.1792 0 - 1.06554
2015-09-02 09:27:01.267301min lat: 0.01405 max lat: 27.6704 avg lat: 1.06554
sec Cur ops started finished avg MB/s cur MB/s last lat avg lat
60 16 897 881 50.4445 0 - 1.06554
cluster 98d89661-f616-49eb-9ccf-84d720e179c0
health HEALTH_OK
monmap e3: 3 mons at
{s01=10.100.50.1:6789/0,s02=10.100.50.2:6789/0,s03=1
0.100.50.3:6789/0 <http://0.100.50.3:6789/0>}, election epoch 666,
quorum 0,1,2 s01,s02,s03
* osdmap e121039: 240 osds: 240 up, 240 in*
pgmap v850698: 7232 pgs, 31 pools, 439 GB data, 43090 kobjects
2635 GB used, 867 TB / 870 TB avail
7226 active+clean
6 active+clean+scrubbing+deep
Note the last line there. You'll likely want to try your test again when scrubbing is complete. Also, you may want to try this script:
Yeah i have tried few times when cluster is perfectly healthy ( not doing scrubbing / repairs )
https://github.com/ceph/cbt/blob/master/tools/readpgdump.py
You can invoke it like:
ceph pg dump | ./readpgdump.py
That will give you a bunch of information about the pools on your system. I'm a little concerned about how many PGs your glance-test pool may have given your totals above.
Thanks for the link i would do that and also run rados bench for other pools ( where PG is higher )
Now here are my some observations
1# When the cluster is not doing anything , Health_ok , with no background scrubbing / repairing. Also all system resources CPU/MEM/NET are mostly idle. In this Case when i start rados bench ( write / rand / seq ) , after suddenly a few seconds
--- rados bench output drops from ~500M to few 10M
--- At the same time CPU busy 90% and System load bumps UP
Once rados bench completes
--- After few minutes System resources becomes IDLE
2# Sometime some PG becomes unclean for a few minutes while rados bench runs and then then quickly they becomes active+clean
I am out of clues , so any help from community that leads me to think in right direction , would be helpful.
- Vickey -
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