Did maximum performance reached?

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Hi,

But my question is why speed is divided between clients?
And how much OSDnodes, OSDdaemos, PGs, I have to add/remove to ceph,
that each cephfs-client could write with his max network speed (10Gbit/s ~ 1.2GB/s)???


________________________________________
From: Johannes Formann <mlmail@xxxxxxxxxx>
Sent: Tuesday, July 28, 2015 12:46 PM
To: Shneur Zalman Mattern
Subject: Re:  Did maximum performance reached?

Hi,

size=3 would decrease your performance. But with size=2 your results are not bad too:
Math:
size=2 means each write is written 4 times (2 copies, first journal, later disk). Calculating with 1.300MB/s „Client“ Bandwidth that means:

2 (size) * 1300 MB/s / 6 (SSD) => 433MB/s each SSD
2 (size) * 1300 MB/s / 30 (HDD) => 87MB/s each HDD


greetings

Johannes

> Am 28.07.2015 um 11:41 schrieb Shneur Zalman Mattern <shzama@xxxxxxxxxxxx>:
>
> Hi, Johannes (that's my grandpa's name)
>
> The size is 2, do you really think that number of replicas can increase performance?
> on the  http://ceph.com/docs/master/architecture/
> written "Note: Striping is independent of object replicas. Since CRUSH replicates objects across OSDs, stripes get replicated automatically. "
>
> OK, I'll check it,
> Regards, Shneur
> ________________________________________
> From: Johannes Formann <mlmail@xxxxxxxxxx>
> Sent: Tuesday, July 28, 2015 12:09 PM
> To: Shneur Zalman Mattern
> Cc: ceph-users@xxxxxxxxxxxxxx
> Subject: Re:  Did maximum performance reached?
>
> Hello,
>
> what is the „size“ parameter of your pool?
>
> Some math do show the impact:
> size=3 means each write is written 6 times (3 copies, first journal, later disk). Calculating with 1.300MB/s „Client“ Bandwidth that means:
>
> 3 (size) * 1300 MB/s / 6 (SSD) => 650MB/s per SSD
> 3 (size) * 1300 MB/s / 30 (HDD) => 130MB/s per HDD
>
> If you use size=3, the results are as good as one can expect. (Even with size=2 the results won’t be bad)
>
> greetings
>
> Johannes
>
>> Am 28.07.2015 um 10:53 schrieb Shneur Zalman Mattern <shzama@xxxxxxxxxxxx>:
>>
>> We've built Ceph cluster:
>>    3 mon nodes (one of them is combined with mds)
>>    3 osd nodes (each one have 10 osd + 2 ssd for journaling)
>>    switch 24 ports x 10G
>>    10 gigabit - for public network
>>    20 gigabit bonding - between osds
>>    Ubuntu 12.04.05
>>    Ceph 0.87.2
>> -----------------------------------------------------
>> Clients has:
>>    10 gigabit for ceph-connection
>>    CentOS 6.6 with kernel 3.19.8 equipped by cephfs-kmodule
>>
>>
>>
>> ====== fio-2.0.13 seqwrite, bs=1M, filesize=10G, parallel-jobs=16 ===========
>> Single client:
>> ++++++++++++++++++++++++++++
>>
>> Starting 16 processes
>>
>> .....below is just 1 job info....
>> trivial-readwrite-grid01: (groupid=0, jobs=1): err= 0: pid=10484: Tue Jul 28 13:26:24 2015
>>  write: io=10240MB, bw=78656KB/s, iops=76 , runt=133312msec
>>    slat (msec): min=1 , max=117 , avg=13.01, stdev=12.57
>>    clat (usec): min=1 , max=68 , avg= 3.61, stdev= 1.99
>>     lat (msec): min=1 , max=117 , avg=13.01, stdev=12.57
>>    clat percentiles (usec):
>>     |  1.00th=[    1],  5.00th=[    2], 10.00th=[    2], 20.00th=[    2],
>>     | 30.00th=[    3], 40.00th=[    3], 50.00th=[    3], 60.00th=[    4],
>>     | 70.00th=[    4], 80.00th=[    5], 90.00th=[    5], 95.00th=[    6],
>>     | 99.00th=[    9], 99.50th=[   10], 99.90th=[   23], 99.95th=[   28],
>>     | 99.99th=[   62]
>>    bw (KB/s)  : min=35790, max=318215, per=6.31%, avg=78816.91, stdev=26397.76
>>    lat (usec) : 2=1.33%, 4=54.43%, 10=43.54%, 20=0.56%, 50=0.11%
>>    lat (usec) : 100=0.03%
>>  cpu          : usr=0.89%, sys=12.85%, ctx=58248, majf=0, minf=9
>>  IO depths    : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
>>     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
>>     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
>>     issued    : total=r=0/w=10240/d=0, short=r=0/w=0/d=0
>>
>> ...what's above repeats 16 times...
>>
>> Run status group 0 (all jobs):
>>  WRITE: io=163840MB, aggrb=1219.8MB/s, minb=78060KB/s, maxb=78655KB/s, mint=133312msec, maxt=134329msec
>>
>> +++++++++++++++++++++++++++++++++
>> Two clients:
>> +++++++++++++++++++++++++++++++++
>> ....below is just 1 job info....
>> trivial-readwrite-gridsrv: (groupid=0, jobs=1): err= 0: pid=10605: Tue Jul 28 14:05:59 2015
>>  write: io=10240MB, bw=43154KB/s, iops=42 , runt=242984msec
>>    slat (usec): min=991 , max=285653 , avg=23716.12, stdev=23960.60
>>    clat (usec): min=1 , max=65 , avg= 3.67, stdev= 2.02
>>     lat (usec): min=994 , max=285664 , avg=23723.39, stdev=23962.22
>>    clat percentiles (usec):
>>     |  1.00th=[    2],  5.00th=[    2], 10.00th=[    2], 20.00th=[    2],
>>     | 30.00th=[    3], 40.00th=[    3], 50.00th=[    3], 60.00th=[    4],
>>     | 70.00th=[    4], 80.00th=[    5], 90.00th=[    5], 95.00th=[    6],
>>     | 99.00th=[    8], 99.50th=[   10], 99.90th=[   28], 99.95th=[   37],
>>     | 99.99th=[   56]
>>    bw (KB/s)  : min=20630, max=276480, per=6.30%, avg=43328.34, stdev=21905.92
>>    lat (usec) : 2=0.84%, 4=49.45%, 10=49.13%, 20=0.37%, 50=0.18%
>>    lat (usec) : 100=0.03%
>>  cpu          : usr=0.49%, sys=5.68%, ctx=31428, majf=0, minf=9
>>  IO depths    : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
>>     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
>>     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
>>     issued    : total=r=0/w=10240/d=0, short=r=0/w=0/d=0
>>
>> ...what's above repeats 16 times...
>>
>> Run status group 0 (all jobs):
>>  WRITE: io=163840MB, aggrb=687960KB/s, minb=42997KB/s, maxb=43270KB/s, mint=242331msec, maxt=243869msec
>>
>> --------- And almost the same(?!) aggregated result from the second client: ---------
>>
>> Run status group 0 (all jobs):
>>  WRITE: io=163840MB, aggrb=679401KB/s, minb=42462KB/s, maxb=42852KB/s, mint=244697msec, maxt=246941msec
>>
>> ----------------- If I'll summarize: ---------------------
>> aggrb1 + aggrb2 = 687960KB/s + 679401KB/s = 1367MB/s
>>
>> it looks like the same bandwidth from just one client aggrb=1219.8MB/s and it was divided? why?
>> Question: If I'll connect 12 clients nodes - each one can write just on 100MB/s?
>> Perhaps, I need to scale out our ceph up to 15(how many?) OSD nodes - and it'll serve 2 clients on the 1.3GB/s (bw of 10gig nic), or not?
>>
>> ============================================================================
>>
>> health HEALTH_OK
>>     monmap e1: 3 mons at {mon1=192.168.56.251:6789/0,mon2=192.168.56.252:6789/0,mon3=192.168.56.253:6789/0}, election epoch 140, quorum 0,1,2 mon1,mon2,mon3
>>     mdsmap e12: 1/1/1 up {0=mon3=up:active}
>>     osdmap e832: 31 osds: 30 up, 30 in
>>      pgmap v106186: 6144 pgs, 3 pools, 2306 GB data, 1379 kobjects
>>            4624 GB used, 104 TB / 109 TB avail
>>                6144 active+clean
>>
>>
>> Perhaps, I don't understand something in Ceph architecture? I thought, that:
>>
>> Each spindel-disk can write ~ 100MB/s , and we have 10 SAS disks on each node = aggregated write speed is ~ 900MB/s (because of striping etc.)
>> And we have 3 OSD nodes, and objects are striped also on 30 osds - I thought it's also aggregateble and we'll get something around 2.5 GB/s, but not...
>>
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