Re: Ceph cluster NO read / write performance :: Ops are blocked

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Hi Nick,

Thanks for responding. Yes, I am.

—Lincoln

> On Sep 17, 2015, at 11:53 AM, Nick Fisk <nick@xxxxxxxxxx> wrote:
> 
> You are getting a fair amount of reads on the disks whilst doing these writes. You're not using cache tiering are you?
> 
>> -----Original Message-----
>> From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of
>> Lincoln Bryant
>> Sent: 17 September 2015 17:42
>> To: ceph-users@xxxxxxxxxxxxxx
>> Subject: Re:  Ceph cluster NO read / write performance :: Ops
>> are blocked
>> 
>> Hello again,
>> 
>> Well, I disabled offloads on the NIC -- didn’t work for me. I also tried setting
>> net.ipv4.tcp_moderate_rcvbuf = 0 as suggested elsewhere in the thread to
>> no avail.
>> 
>> Today I was watching iostat on an OSD box ('iostat -xm 5') when the cluster
>> got into “slow” state:
>> 
>> Device:         rrqm/s   wrqm/s     r/s     w/s    rMB/s    wMB/s avgrq-sz avgqu-sz
>> await  svctm  %util
>> sdb               0.00    13.57   84.23  167.47     0.45     2.78    26.26     2.06    8.18   3.85
>> 96.93
>> sdc               0.00    46.71    5.59  289.22     0.03     2.54    17.85     3.18   10.77   0.97
>> 28.72
>> sdd               0.00    16.57   45.11   91.62     0.25     0.55    12.01     0.75    5.51   2.45
>> 33.47
>> sde               0.00    13.57    6.99  143.31     0.03     2.53    34.97     1.99   13.27   2.12
>> 31.86
>> sdf               0.00    18.76    4.99  158.48     0.10     1.09    14.88     1.26    7.69   1.24
>> 20.26
>> sdg               0.00    25.55   81.64  237.52     0.44     2.89    21.36     4.14   12.99   2.58
>> 82.22
>> sdh               0.00    89.42   16.17  492.42     0.09     3.81    15.69    17.12   33.66   0.73
>> 36.95
>> sdi               0.00    20.16   17.76  189.62     0.10     1.67    17.46     3.45   16.63   1.57
>> 32.55
>> sdj               0.00    31.54    0.00  185.23     0.00     1.91    21.15     3.33   18.00   0.03
>> 0.62
>> sdk               0.00    26.15    2.40  133.33     0.01     0.84    12.79     1.07    7.87   0.85
>> 11.58
>> sdl               0.00    25.55    9.38  123.95     0.05     1.15    18.44     0.50    3.74   1.58
>> 21.10
>> sdm               0.00     6.39   92.61   47.11     0.47     0.26    10.65     1.27    9.07   6.92
>> 96.73
>> 
>> The %util is rather high on some disks, but I’m not an expert at looking at
>> iostat so I’m not sure how worrisome this is. Does anything here stand out to
>> anyone?
>> 
>> At the time of that iostat, Ceph was reporting a lot of blocked ops on the OSD
>> associated with sde (as well as about 30 other OSDs), but it doesn’t look all
>> that busy. Some simple ‘dd’ tests seem to indicate the disk is fine.
>> 
>> Similarly, iotop seems OK on this host:
>> 
>>  TID  PRIO  USER     DISK READ  DISK WRITE  SWAPIN     IO>    COMMAND
>> 472477 be/4 root        0.00 B/s    5.59 M/s  0.00 %  0.57 % ceph-osd -i 111 --pid-
>> file /var/run/ceph/osd.111.pid -c /etc/ceph/ceph.conf --cluster ceph
>> 470621 be/4 root        0.00 B/s   10.09 M/s  0.00 %  0.40 % ceph-osd -i 111 --pid-
>> file /var/run/ceph/osd.111.pid -c /etc/ceph/ceph.conf --cluster ceph
>> 3495447 be/4 root        0.00 B/s  272.19 K/s  0.00 %  0.36 % ceph-osd -i 114 --
>> pid-file /var/run/ceph/osd.114.pid -c /etc/ceph/ceph.conf --cluster ceph
>> 3488389 be/4 root	 0.00 B/s  596.80 K/s  0.00 %  0.16 % ceph-osd -i 109 --
>> pid-file /var/run/ceph/osd.109.pid -c /etc/ceph/ceph.conf --cluster ceph
>> 3488060 be/4 root        0.00 B/s  600.83 K/s  0.00 %  0.15 % ceph-osd -i 108 --
>> pid-file /var/run/ceph/osd.108.pid -c /etc/ceph/ceph.conf --cluster ceph
>> 3505573 be/4 root        0.00 B/s  528.25 K/s  0.00 %  0.10 % ceph-osd -i 119 --
>> pid-file /var/run/ceph/osd.119.pid -c /etc/ceph/ceph.conf --cluster ceph
>> 3495434 be/4 root        0.00 B/s    2.02 K/s  0.00 %  0.10 % ceph-osd -i 114 --pid-
>> file /var/run/ceph/osd.114.pid -c /etc/ceph/ceph.conf --cluster ceph
>> 3502327 be/4 root        0.00 B/s  506.07 K/s  0.00 %  0.09 % ceph-osd -i 118 --
>> pid-file /var/run/ceph/osd.118.pid -c /etc/ceph/ceph.conf --cluster ceph
>> 3489100 be/4 root        0.00 B/s  106.86 K/s  0.00 %  0.09 % ceph-osd -i 110 --
>> pid-file /var/run/ceph/osd.110.pid -c /etc/ceph/ceph.conf --cluster ceph
>> 3496631 be/4 root        0.00 B/s  229.85 K/s  0.00 %  0.05 % ceph-osd -i 115 --
>> pid-file /var/run/ceph/osd.115.pid -c /etc/ceph/ceph.conf --cluster ceph
>> 3505561 be/4 root	 0.00 B/s    2.02 K/s  0.00 %  0.03 % ceph-osd -i 119 --
>> pid-file /var/run/ceph/osd.119.pid -c /etc/ceph/ceph.conf --cluster ceph
>> 3488059 be/4 root        0.00 B/s    2.02 K/s  0.00 %  0.03 % ceph-osd -i 108 --pid-
>> file /var/run/ceph/osd.108.pid -c /etc/ceph/ceph.conf --cluster ceph
>> 3488391 be/4 root       46.37 K/s  431.47 K/s  0.00 %  0.02 % ceph-osd -i 109 --
>> pid-file /var/run/ceph/osd.109.pid -c /etc/ceph/ceph.conf --cluster ceph
>> 3500639 be/4 root        0.00 B/s  221.78 K/s  0.00 %  0.02 % ceph-osd -i 117 --
>> pid-file /var/run/ceph/osd.117.pid -c /etc/ceph/ceph.conf --cluster ceph
>> 3488392 be/4 root       34.28 K/s  185.49 K/s  0.00 %  0.02 % ceph-osd -i 109 --
>> pid-file /var/run/ceph/osd.109.pid -c /etc/ceph/ceph.conf --cluster ceph
>> 3488062 be/4 root        4.03 K/s   66.54 K/s  0.00 %  0.02 % ceph-osd -i 108 --pid-
>> file /var/run/ceph/osd.108.pid -c /etc/ceph/ceph.conf --cluster ceph
>> 
>> These are all 6TB seagates in single-disk RAID 0 on a PERC H730 Mini
>> controller.
>> 
>> I did try removing the disk with 20k non-medium errors, but that didn’t seem
>> to help.
>> 
>> Thanks for any insight!
>> 
>> Cheers,
>> Lincoln Bryant
>> 
>>> On Sep 9, 2015, at 1:09 PM, Lincoln Bryant <lincolnb@xxxxxxxxxxxx> wrote:
>>> 
>>> Hi Jan,
>>> 
>>> I’ll take a look at all of those things and report back (hopefully :))
>>> 
>>> I did try setting all of my OSDs to writethrough instead of writeback on the
>> controller, which was significantly more consistent in performance (from
>> 1100MB/s down to 300MB/s, but still occasionally dropping to 0MB/s). Still
>> plenty of blocked ops.
>>> 
>>> I was wondering if not-so-nicely failing OSD(s) might be the cause. My
>> controller (PERC H730 Mini) seems frustratingly terse with SMART
>> information, but at least one disk has a “Non-medium error count” of over
>> 20,000..
>>> 
>>> I’ll try disabling offloads as well.
>>> 
>>> Thanks much for the suggestions!
>>> 
>>> Cheers,
>>> Lincoln
>>> 
>>>> On Sep 9, 2015, at 3:59 AM, Jan Schermer <jan@xxxxxxxxxxx> wrote:
>>>> 
>>>> Just to recapitulate - the nodes are doing "nothing" when it drops to zero?
>> Not flushing something to drives (iostat)? Not cleaning pagecache (kswapd
>> and similiar)? Not out of any type of memory (slab, min_free_kbytes)? Not
>> network link errors, no bad checksums (those are hard to spot, though)?
>>>> 
>>>> Unless you find something I suggest you try disabling offloads on the NICs
>> and see if the problem goes away.
>>>> 
>>>> Jan
>>>> 
>>>>> On 08 Sep 2015, at 18:26, Lincoln Bryant <lincolnb@xxxxxxxxxxxx> wrote:
>>>>> 
>>>>> For whatever it’s worth, my problem has returned and is very similar to
>> yours. Still trying to figure out what’s going on over here.
>>>>> 
>>>>> Performance is nice for a few seconds, then goes to 0. This is a
>>>>> similar setup to yours (12 OSDs per box, Scientific Linux 6, Ceph
>>>>> 0.94.3, etc)
>>>>> 
>>>>> 384      16     29520     29504   307.287      1188 0.0492006  0.208259
>>>>> 385      16     29813     29797   309.532      1172 0.0469708  0.206731
>>>>> 386      16     30105     30089   311.756      1168 0.0375764  0.205189
>>>>> 387      16     30401     30385   314.009      1184  0.036142  0.203791
>>>>> 388      16     30695     30679   316.231      1176 0.0372316  0.202355
>>>>> 389      16     30987     30971    318.42      1168 0.0660476  0.200962
>>>>> 390      16     31282     31266   320.628      1180 0.0358611  0.199548
>>>>> 391      16     31568     31552   322.734      1144 0.0405166  0.198132
>>>>> 392      16     31857     31841   324.859      1156 0.0360826  0.196679
>>>>> 393      16     32090     32074   326.404       932 0.0416869   0.19549
>>>>> 394      16     32205     32189   326.743       460 0.0251877  0.194896
>>>>> 395      16     32302     32286   326.897       388 0.0280574  0.194395
>>>>> 396      16     32348     32332   326.537       184 0.0256821  0.194157
>>>>> 397      16     32385     32369   326.087       148 0.0254342  0.193965
>>>>> 398      16     32424     32408   325.659       156 0.0263006  0.193763
>>>>> 399      16     32445     32429   325.054        84 0.0233839  0.193655
>>>>> 2015-09-08 11:22:31.940164 min lat: 0.0165045 max lat: 67.6184 avg lat:
>> 0.193655
>>>>> sec Cur ops   started  finished  avg MB/s  cur MB/s  last lat   avg lat
>>>>> 400      16     32445     32429   324.241         0         -  0.193655
>>>>> 401      16     32445     32429   323.433         0         -  0.193655
>>>>> 402      16     32445     32429   322.628         0         -  0.193655
>>>>> 403      16     32445     32429   321.828         0         -  0.193655
>>>>> 404      16     32445     32429   321.031         0         -  0.193655
>>>>> 405      16     32445     32429   320.238         0         -  0.193655
>>>>> 406      16     32445     32429    319.45         0         -  0.193655
>>>>> 407      16     32445     32429   318.665         0         -  0.193655
>>>>> 
>>>>> needless to say, very strange.
>>>>> 
>>>>> —Lincoln
>>>>> 
>>>>> 
>>>>>> On Sep 7, 2015, at 3:35 PM, Vickey Singh
>> <vickey.singh22693@xxxxxxxxx> wrote:
>>>>>> 
>>>>>> Adding ceph-users.
>>>>>> 
>>>>>> On Mon, Sep 7, 2015 at 11:31 PM, Vickey Singh
>> <vickey.singh22693@xxxxxxxxx> wrote:
>>>>>> 
>>>>>> 
>>>>>> On Mon, Sep 7, 2015 at 10:04 PM, Udo Lembke
>> <ulembke@xxxxxxxxxxxx> wrote:
>>>>>> Hi Vickey,
>>>>>> Thanks for your time in replying to my problem.
>>>>>> 
>>>>>> I had the same rados bench output after changing the motherboard of
>> the monitor node with the lowest IP...
>>>>>> Due to the new mainboard, I assume the hw-clock was wrong during
>> startup. Ceph health show no errors, but all VMs aren't able to do IO (very
>> high load on the VMs - but no traffic).
>>>>>> I stopped the mon, but this don't changed anything. I had to restart all
>> other mons to get IO again. After that I started the first mon also (with the
>> right time now) and all worked fine again...
>>>>>> 
>>>>>> Thanks i will try to restart all OSD / MONS and report back , if it
>>>>>> solves my problem
>>>>>> 
>>>>>> Another posibility:
>>>>>> Do you use journal on SSDs? Perhaps the SSDs can't write to garbage
>> collection?
>>>>>> 
>>>>>> No i don't have journals on SSD , they are on the same OSD disk.
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> Udo
>>>>>> 
>>>>>> 
>>>>>> On 07.09.2015 16:36, Vickey Singh wrote:
>>>>>>> Dear Experts
>>>>>>> 
>>>>>>> Can someone please help me , why my cluster is not able write data.
>>>>>>> 
>>>>>>> See the below output  cur MB/S  is 0  and Avg MB/s is decreasing.
>>>>>>> 
>>>>>>> 
>>>>>>> Ceph Hammer  0.94.2
>>>>>>> CentOS 6 (3.10.69-1)
>>>>>>> 
>>>>>>> The Ceph status says OPS are blocked , i have tried checking ,
>>>>>>> what all i know
>>>>>>> 
>>>>>>> - System resources ( CPU , net, disk , memory )    -- All normal
>>>>>>> - 10G network for public and cluster network  -- no saturation
>>>>>>> - Add disks are physically healthy
>>>>>>> - No messages in /var/log/messages OR dmesg
>>>>>>> - Tried restarting OSD which are blocking operation , but no luck
>>>>>>> - Tried writing through RBD  and Rados bench , both are giving
>>>>>>> same problemm
>>>>>>> 
>>>>>>> Please help me to fix this problem.
>>>>>>> 
>>>>>>> #  rados bench -p rbd 60 write
>>>>>>> Maintaining 16 concurrent writes of 4194304 bytes for up to 60
>>>>>>> seconds or 0 objects Object prefix: benchmark_data_stor1_1791844
>>>>>>> sec Cur ops   started  finished  avg MB/s  cur MB/s  last lat   avg lat
>>>>>>>  0       0         0         0         0         0         -         0
>>>>>>>  1      16       125       109   435.873       436  0.022076 0.0697864
>>>>>>>  2      16       139       123   245.948        56  0.246578 0.0674407
>>>>>>>  3      16       139       123   163.969         0         - 0.0674407
>>>>>>>  4      16       139       123   122.978         0         - 0.0674407
>>>>>>>  5      16       139       123    98.383         0         - 0.0674407
>>>>>>>  6      16       139       123   81.9865         0         - 0.0674407
>>>>>>>  7      16       139       123   70.2747         0         - 0.0674407
>>>>>>>  8      16       139       123   61.4903         0         - 0.0674407
>>>>>>>  9      16       139       123   54.6582         0         - 0.0674407
>>>>>>> 10      16       139       123   49.1924         0         - 0.0674407
>>>>>>> 11      16       139       123   44.7201         0         - 0.0674407
>>>>>>> 12      16       139       123   40.9934         0         - 0.0674407
>>>>>>> 13      16       139       123   37.8401         0         - 0.0674407
>>>>>>> 14      16       139       123   35.1373         0         - 0.0674407
>>>>>>> 15      16       139       123   32.7949         0         - 0.0674407
>>>>>>> 16      16       139       123   30.7451         0         - 0.0674407
>>>>>>> 17      16       139       123   28.9364         0         - 0.0674407
>>>>>>> 18      16       139       123   27.3289         0         - 0.0674407
>>>>>>> 19      16       139       123   25.8905         0         - 0.0674407
>>>>>>> 2015-09-07 15:54:52.694071min lat: 0.022076 max lat: 0.46117 avg lat:
>> 0.0674407
>>>>>>> sec Cur ops   started  finished  avg MB/s  cur MB/s  last lat   avg lat
>>>>>>> 20      16       139       123    24.596         0         - 0.0674407
>>>>>>> 21      16       139       123   23.4247         0         - 0.0674407
>>>>>>> 22      16       139       123     22.36         0         - 0.0674407
>>>>>>> 23      16       139       123   21.3878         0         - 0.0674407
>>>>>>> 24      16       139       123   20.4966         0         - 0.0674407
>>>>>>> 25      16       139       123   19.6768         0         - 0.0674407
>>>>>>> 26      16       139       123     18.92         0         - 0.0674407
>>>>>>> 27      16       139       123   18.2192         0         - 0.0674407
>>>>>>> 28      16       139       123   17.5686         0         - 0.0674407
>>>>>>> 29      16       139       123   16.9628         0         - 0.0674407
>>>>>>> 30      16       139       123   16.3973         0         - 0.0674407
>>>>>>> 31      16       139       123   15.8684         0         - 0.0674407
>>>>>>> 32      16       139       123   15.3725         0         - 0.0674407
>>>>>>> 33      16       139       123   14.9067         0         - 0.0674407
>>>>>>> 34      16       139       123   14.4683         0         - 0.0674407
>>>>>>> 35      16       139       123   14.0549         0         - 0.0674407
>>>>>>> 36      16       139       123   13.6645         0         - 0.0674407
>>>>>>> 37      16       139       123   13.2952         0         - 0.0674407
>>>>>>> 38      16       139       123   12.9453         0         - 0.0674407
>>>>>>> 39      16       139       123   12.6134         0         - 0.0674407
>>>>>>> 2015-09-07 15:55:12.697124min lat: 0.022076 max lat: 0.46117 avg lat:
>> 0.0674407
>>>>>>> sec Cur ops   started  finished  avg MB/s  cur MB/s  last lat   avg lat
>>>>>>> 40      16       139       123   12.2981         0         - 0.0674407
>>>>>>> 41      16       139       123   11.9981         0         - 0.0674407
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> cluster 86edf8b8-b353-49f1-ab0a-a4827a9ea5e8
>>>>>>>  health HEALTH_WARN
>>>>>>>         1 requests are blocked > 32 sec
>>>>>>>  monmap e3: 3 mons at
>>>>>>> {stor0111=10.100.1.111:6789/0,stor0113=10.100.1.113:6789/0,stor011
>>>>>>> 5=10.100.1.115:6789/0}
>>>>>>>         election epoch 32, quorum 0,1,2 stor0111,stor0113,stor0115
>>>>>>>  osdmap e19536: 50 osds: 50 up, 50 in
>>>>>>>   pgmap v928610: 2752 pgs, 9 pools, 30476 GB data, 4183 kobjects
>>>>>>>         91513 GB used, 47642 GB / 135 TB avail
>>>>>>>             2752 active+clean
>>>>>>> 
>>>>>>> 
>>>>>>> Tried using RBD
>>>>>>> 
>>>>>>> 
>>>>>>> # dd if=/dev/zero of=file1 bs=4K count=10000 oflag=direct
>>>>>>> 10000+0 records in
>>>>>>> 10000+0 records out
>>>>>>> 40960000 bytes (41 MB) copied, 24.5529 s, 1.7 MB/s
>>>>>>> 
>>>>>>> # dd if=/dev/zero of=file1 bs=1M count=100 oflag=direct
>>>>>>> 100+0 records in
>>>>>>> 100+0 records out
>>>>>>> 104857600 bytes (105 MB) copied, 1.05602 s, 9.3 MB/s
>>>>>>> 
>>>>>>> # dd if=/dev/zero of=file1 bs=1G count=1 oflag=direct
>>>>>>> 1+0 records in
>>>>>>> 1+0 records out
>>>>>>> 1073741824 bytes (1.1 GB) copied, 293.551 s, 3.7 MB/s ]#
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> _______________________________________________
>>>>>>> ceph-users mailing list
>>>>>>> 
>>>>>>> ceph-users@xxxxxxxxxxxxxx
>>>>>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> _______________________________________________
>>>>>> ceph-users mailing list
>>>>>> ceph-users@xxxxxxxxxxxxxx
>>>>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>>>>> 
>>>>> _______________________________________________
>>>>> ceph-users mailing list
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>>>> 
>>> 
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>> 
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