НА: НА: CEPH cache layer. Very slow

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Hi!

6 nodes, 70 OSDs (1-2-4Tb sata drives).
Ceph used as RBD backstore for VM images (~100VMs).

Megov Igor
CIO, Yuterra


________________________________________
От: Ben Hines <bhines@xxxxxxxxx>
Отправлено: 14 августа 2015 г. 21:01
Кому: Межов Игорь Александрович
Копия: Voloshanenko Igor; ceph-users@xxxxxxxxxxxxxx
Тема: Re:  НА: CEPH cache layer. Very slow

Nice to hear that you have no SSD failures yet in 10months.

How many OSDs are you running, and what is your primary ceph workload?
(RBD, rgw, etc?)

-Ben

On Fri, Aug 14, 2015 at 2:23 AM, Межов Игорь Александрович
<megov@xxxxxxxxxx> wrote:
> Hi!
>
>
> Of course, it isn't cheap at all, but we use Intel DC S3700 200Gb for ceph
> journals
> and DC S3700 400Gb in the SSD pool: same hosts, separate root in crushmap.
>
> SSD pool are not yet in production, journаlling SSDs works under production
> load
> for 10 months. They're in good condition - no faults, no degradation.
>
> We specially take 200Gb SSD for journals to reduce costs, and also have a
> higher
> than recommended OSD/SSD ratio: 1 SSD per 10-12 ODS, whille recommended
> 1/3 to 1/6.
>
> So, as a conclusion - I'll recommend you to get a bigger budget and buy
> durable
> and fast SSDs for Ceph.
>
> Megov Igor
> CIO, Yuterra
>
> ________________________________
> От: ceph-users <ceph-users-bounces@xxxxxxxxxxxxxx> от имени Voloshanenko
> Igor <igor.voloshanenko@xxxxxxxxx>
> Отправлено: 13 августа 2015 г. 15:54
> Кому: Jan Schermer
> Копия: ceph-users@xxxxxxxxxxxxxx
> Тема: Re:  CEPH cache layer. Very slow
>
> So, good, but price for 845 DC PRO 400 GB higher in about 2x times than
> intel S3500 240G (((
>
> Any other models? (((
>
> 2015-08-13 15:45 GMT+03:00 Jan Schermer <jan@xxxxxxxxxxx>:
>>
>> I tested and can recommend the Samsung 845 DC PRO (make sure it is DC PRO
>> and not just "PRO" or "DC EVO"!).
>> Those were very cheap but are out of stock at the moment (here).
>> Faster than Intels, cheaper, and slightly different technology (3D V-NAND)
>> which IMO makes them superior without needing many tricks to do its job.
>>
>> Jan
>>
>> On 13 Aug 2015, at 14:40, Voloshanenko Igor <igor.voloshanenko@xxxxxxxxx>
>> wrote:
>>
>> Tnx, Irek! Will try!
>>
>> but another question to all, which SSD good enough for CEPH now?
>>
>> I'm looking into S3500 240G (I have some S3500 120G which show great
>> results. Around 8x times better than Samsung)
>>
>> Possible you can give advice about other vendors/models with same or below
>> price level as S3500 240G?
>>
>> 2015-08-13 12:11 GMT+03:00 Irek Fasikhov <malmyzh@xxxxxxxxx>:
>>>
>>> Hi, Igor.
>>> Try to roll the patch here:
>>>
>>> http://www.theirek.com/blog/2014/02/16/patch-dlia-raboty-s-enierghoniezavisimym-keshiem-ssd-diskov
>>>
>>> P.S. I am no longer tracks changes in this direction(kernel), because we
>>> use already recommended SSD
>>>
>>> С уважением, Фасихов Ирек Нургаязович
>>> Моб.: +79229045757
>>>
>>> 2015-08-13 11:56 GMT+03:00 Voloshanenko Igor
>>> <igor.voloshanenko@xxxxxxxxx>:
>>>>
>>>> So, after testing SSD (i wipe 1 SSD, and used it for tests)
>>>>
>>>> root@ix-s2:~# sudo fio --filename=/dev/sda --direct=1 --sync=1
>>>> --rw=write --bs=4k --numjobs=1 --iodepth=1 --runtime=60 --time_based
>>>> --gr[53/1800]
>>>> ting --name=journal-test
>>>> journal-test: (g=0): rw=write, bs=4K-4K/4K-4K/4K-4K, ioengine=sync,
>>>> iodepth=1
>>>> fio-2.1.3
>>>> Starting 1 process
>>>> Jobs: 1 (f=1): [W] [100.0% done] [0KB/1152KB/0KB /s] [0/288/0 iops] [eta
>>>> 00m:00s]
>>>> journal-test: (groupid=0, jobs=1): err= 0: pid=2849460: Thu Aug 13
>>>> 10:46:42 2015
>>>>   write: io=68972KB, bw=1149.6KB/s, iops=287, runt= 60001msec
>>>>     clat (msec): min=2, max=15, avg= 3.48, stdev= 1.08
>>>>      lat (msec): min=2, max=15, avg= 3.48, stdev= 1.08
>>>>     clat percentiles (usec):
>>>>      |  1.00th=[ 2704],  5.00th=[ 2800], 10.00th=[ 2864], 20.00th=[
>>>> 2928],
>>>>      | 30.00th=[ 3024], 40.00th=[ 3088], 50.00th=[ 3280], 60.00th=[
>>>> 3408],
>>>>      | 70.00th=[ 3504], 80.00th=[ 3728], 90.00th=[ 3856], 95.00th=[
>>>> 4016],
>>>>      | 99.00th=[ 9024], 99.50th=[ 9280], 99.90th=[ 9792],
>>>> 99.95th=[10048],
>>>>      | 99.99th=[14912]
>>>>     bw (KB  /s): min= 1064, max= 1213, per=100.00%, avg=1150.07,
>>>> stdev=34.31
>>>>     lat (msec) : 4=94.99%, 10=4.96%, 20=0.05%
>>>>   cpu          : usr=0.13%, sys=0.57%, ctx=17248, majf=0, minf=7
>>>>   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=17243/d=0, short=r=0/w=0/d=0
>>>>
>>>> Run status group 0 (all jobs):
>>>>   WRITE: io=68972KB, aggrb=1149KB/s, minb=1149KB/s, maxb=1149KB/s,
>>>> mint=60001msec, maxt=60001msec
>>>>
>>>> Disk stats (read/write):
>>>>   sda: ios=0/17224, merge=0/0, ticks=0/59584, in_queue=59576,
>>>> util=99.30%
>>>>
>>>> So, it's pain... SSD do only 287 iops on 4K... 1,1 MB/s
>>>>
>>>> I try to change cache mode :
>>>> echo temporary write through > /sys/class/scsi_disk/2:0:0:0/cache_type
>>>> echo temporary write through > /sys/class/scsi_disk/3:0:0:0/cache_type
>>>>
>>>> no luck, still same shit results, also i found this article:
>>>> https://lkml.org/lkml/2013/11/20/264 pointed to old very simple patch,
>>>> which disable CMD_FLUSH
>>>> https://gist.github.com/TheCodeArtist/93dddcd6a21dc81414ba
>>>>
>>>> Has everybody better ideas, how to improve this? (or disable CMD_FLUSH
>>>> without recompile kernel, i used ubuntu and 4.0.4 for now (4.x branch
>>>> because SSD 850 Pro have issue with NCQ TRIM< and before 4.0.4 this
>>>> exception was not included into libsata.c)
>>>>
>>>> 2015-08-12 19:17 GMT+03:00 Pieter Koorts <pieter.koorts@xxxxxx>:
>>>>>
>>>>> Hi Igor
>>>>>
>>>>> I suspect you have very much the same problem as me.
>>>>>
>>>>> https://www.mail-archive.com/ceph-users@xxxxxxxxxxxxxx/msg22260.html
>>>>>
>>>>> Basically Samsung drives (like many SATA SSD's) are very much hit and
>>>>> miss so you will need to test them like described here to see if they are
>>>>> any good.
>>>>> http://www.sebastien-han.fr/blog/2014/10/10/ceph-how-to-test-if-your-ssd-is-suitable-as-a-journal-device/
>>>>>
>>>>> To give you an idea my average performance went from 11MB/s (with
>>>>> Samsung SSD) to 30MB/s (without any SSD) on write performance. This is a
>>>>> very small cluster.
>>>>>
>>>>> Pieter
>>>>>
>>>>> On Aug 12, 2015, at 04:33 PM, Voloshanenko Igor
>>>>> <igor.voloshanenko@xxxxxxxxx> wrote:
>>>>>
>>>>> Hi all, we have setup CEPH cluster with 60 OSD (2 diff types) (5 nodes,
>>>>> 12 disks on each, 10 HDD, 2 SSD)
>>>>>
>>>>> Also we cover this with custom crushmap with 2 root leaf
>>>>>
>>>>> ID   WEIGHT  TYPE NAME              UP/DOWN REWEIGHT PRIMARY-AFFINITY
>>>>> -100 5.00000 root ssd
>>>>> -102 1.00000     host ix-s2-ssd
>>>>>    2 1.00000         osd.2               up  1.00000          1.00000
>>>>>    9 1.00000         osd.9               up  1.00000          1.00000
>>>>> -103 1.00000     host ix-s3-ssd
>>>>>    3 1.00000         osd.3               up  1.00000          1.00000
>>>>>    7 1.00000         osd.7               up  1.00000          1.00000
>>>>> -104 1.00000     host ix-s5-ssd
>>>>>    1 1.00000         osd.1               up  1.00000          1.00000
>>>>>    6 1.00000         osd.6               up  1.00000          1.00000
>>>>> -105 1.00000     host ix-s6-ssd
>>>>>    4 1.00000         osd.4               up  1.00000          1.00000
>>>>>    8 1.00000         osd.8               up  1.00000          1.00000
>>>>> -106 1.00000     host ix-s7-ssd
>>>>>    0 1.00000         osd.0               up  1.00000          1.00000
>>>>>    5 1.00000         osd.5               up  1.00000          1.00000
>>>>>   -1 5.00000 root platter
>>>>>   -2 1.00000     host ix-s2-platter
>>>>>   13 1.00000         osd.13              up  1.00000          1.00000
>>>>>   17 1.00000         osd.17              up  1.00000          1.00000
>>>>>   21 1.00000         osd.21              up  1.00000          1.00000
>>>>>   27 1.00000         osd.27              up  1.00000          1.00000
>>>>>   32 1.00000         osd.32              up  1.00000          1.00000
>>>>>   37 1.00000         osd.37              up  1.00000          1.00000
>>>>>   44 1.00000         osd.44              up  1.00000          1.00000
>>>>>   48 1.00000         osd.48              up  1.00000          1.00000
>>>>>   55 1.00000         osd.55              up  1.00000          1.00000
>>>>>   59 1.00000         osd.59              up  1.00000          1.00000
>>>>>   -3 1.00000     host ix-s3-platter
>>>>>   14 1.00000         osd.14              up  1.00000          1.00000
>>>>>   18 1.00000         osd.18              up  1.00000          1.00000
>>>>>   23 1.00000         osd.23              up  1.00000          1.00000
>>>>>   28 1.00000         osd.28              up  1.00000          1.00000
>>>>>   33 1.00000         osd.33              up  1.00000          1.00000
>>>>>   39 1.00000         osd.39              up  1.00000          1.00000
>>>>>   43 1.00000         osd.43              up  1.00000          1.00000
>>>>>   47 1.00000         osd.47              up  1.00000          1.00000
>>>>>   54 1.00000         osd.54              up  1.00000          1.00000
>>>>>   58 1.00000         osd.58              up  1.00000          1.00000
>>>>>   -4 1.00000     host ix-s5-platter
>>>>>   11 1.00000         osd.11              up  1.00000          1.00000
>>>>>   16 1.00000         osd.16              up  1.00000          1.00000
>>>>>   22 1.00000         osd.22              up  1.00000          1.00000
>>>>>   26 1.00000         osd.26              up  1.00000          1.00000
>>>>>   31 1.00000         osd.31              up  1.00000          1.00000
>>>>>   36 1.00000         osd.36              up  1.00000          1.00000
>>>>>   41 1.00000         osd.41              up  1.00000          1.00000
>>>>>   46 1.00000         osd.46              up  1.00000          1.00000
>>>>>   51 1.00000         osd.51              up  1.00000          1.00000
>>>>>   56 1.00000         osd.56              up  1.00000          1.00000
>>>>>   -5 1.00000     host ix-s6-platter
>>>>>   12 1.00000         osd.12              up  1.00000          1.00000
>>>>>   19 1.00000         osd.19              up  1.00000          1.00000
>>>>>  24 1.00000         osd.24              up  1.00000          1.00000
>>>>>   29 1.00000         osd.29              up  1.00000          1.00000
>>>>>   34 1.00000         osd.34              up  1.00000          1.00000
>>>>>   38 1.00000         osd.38              up  1.00000          1.00000
>>>>>   42 1.00000         osd.42              up  1.00000          1.00000
>>>>>   50 1.00000         osd.50              up  1.00000          1.00000
>>>>>   53 1.00000         osd.53              up  1.00000          1.00000
>>>>>   57 1.00000         osd.57              up  1.00000          1.00000
>>>>>   -6 1.00000     host ix-s7-platter
>>>>>   10 1.00000         osd.10              up  1.00000          1.00000
>>>>>   15 1.00000         osd.15              up  1.00000          1.00000
>>>>>   20 1.00000         osd.20              up  1.00000          1.00000
>>>>>   25 1.00000         osd.25              up  1.00000          1.00000
>>>>>   30 1.00000         osd.30              up  1.00000          1.00000
>>>>>   35 1.00000         osd.35              up  1.00000          1.00000
>>>>>   40 1.00000         osd.40              up  1.00000          1.00000
>>>>>   45 1.00000         osd.45              up  1.00000          1.00000
>>>>>   49 1.00000         osd.49              up  1.00000          1.00000
>>>>>   52 1.00000         osd.52              up  1.00000          1.00000
>>>>>
>>>>>
>>>>> Then create 2 pools, 1 on HDD (platters), 1 on SSD/
>>>>> and put SSD pul in from of HDD pool (cache tier)
>>>>>
>>>>> now we receive very bad performance results from cluster.
>>>>> Even with rados bench we received very unstable performance with even
>>>>> zero speed. So it's create very big issues for our clients.
>>>>>
>>>>> I try to tune all possible values, including OSD, but still no luck.
>>>>>
>>>>> Also very unbelievble situation, when i do
>>>>> ceph tell... bench on SSD OSD - i receive about 20MB/s
>>>>> If for HDD - 67 MB/s...
>>>>>
>>>>> I don;t understand why cache pools which consist of SSD works so bad...
>>>>> We used Samsung 850 Pro 256 Gb as SSDs
>>>>>
>>>>> Can you guys give me advice please...
>>>>>
>>>>> Also very idiotic thing, when i set cache-mode to forward and try to
>>>>> flush-evict all object (not all object evicted, some busy (locked on KVM
>>>>> sides). but now i receive quite stable results for rados bench
>>>>>
>>>>>  Total time run:         30.275871
>>>>> Total writes made:      2076
>>>>> Write size:             4194304
>>>>> Bandwidth (MB/sec):     274.278
>>>>>
>>>>> Stddev Bandwidth:       75.1445
>>>>> Max bandwidth (MB/sec): 368
>>>>> Min bandwidth (MB/sec): 0
>>>>> Average Latency:        0.232892
>>>>> Stddev Latency:         0.240356
>>>>> Max latency:            2.01436
>>>>> Min latency:            0.0716344
>>>>>
>>>>> Without zeros, etc...  So i don't understand how it's possible.
>>>>>
>>>>> Also interesting thing, when i disable overlay for pool, rados bench
>>>>> become around 70MB/s as for ordinary HDD, but in same time rados bench for
>>>>> SSD pool, which not used anymore show same bad results...
>>>>>
>>>>> So please, give me some direction to deeg...
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> ceph-users mailing list
>>>>> ceph-users@xxxxxxxxxxxxxx
>>>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>>>>
>>>>
>>>>
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>>>>
>>>
>>
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