Re: Debugging 'slow requests' ...

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Thanks a lot Brad !

The problem is indeed in the network: we moved the OSD nodes back to the "old" switches and the problem disappeared.

Now we have to figure out what is wrong/misconfigured with the new switch: we would try to replicate the problem, possibly without a ceph deployment ...

Thanks again for your help !

Cheers, Massimo

On Sun, Feb 10, 2019 at 12:07 AM Brad Hubbard <bhubbard@xxxxxxxxxx> wrote:
The log ends at

$ zcat ceph-osd.5.log.gz |tail -2
2019-02-09 07:37:00.022534 7f5fce60d700  1 --
192.168.61.202:6816/157436 >> - conn(0x56308edcf000 :6816
s=STATE_ACCEPTING pgs=0 cs=0 l=0)._process_connection sd=296 -

The last two messages are outbound to 192.168.222.204 and there are no
further messages between these two hosts (other than osd_pings) in the
log.

$ zcat ceph-osd.5.log.gz |gawk
'!/osd_ping/&&/192.168.222.202/&&/192.168.222.204/&&/07:29:3/'|tail -5
2019-02-09 07:29:34.267744 7f5fcee0e700  1 --
192.168.222.202:6816/157436 <== osd.29 192.168.222.204:6804/4159520
1946 ==== rep_scrubmap(8.2bc e1205735 from shard 29) v2 ==== 40+0+1492
(3695125937 0 2050362985) 0x563090674d80 con 0x56308bf61000
2019-02-09 07:29:34.375223 7f5faf4b4700  1 --
192.168.222.202:6816/157436 --> 192.168.222.204:6804/4159520 --
replica_scrub(pg:
8.2bc,from:0'0,to:0'0,epoch:1205833/1205735,start:8:3d4e6145:::rbd_data.35f46d19abe4ed.00000000000077a4:0,end:8:3d4e6916:::rbd_data.a6dc2425de9600.000000000006249c:0,chunky:1,deep:0,version:9,allow_preemption:1,priority=5)
v9 -- 0x56308bdf2000 con 0
2019-02-09 07:29:34.378535 7f5fcee0e700  1 --
192.168.222.202:6816/157436 <== osd.29 192.168.222.204:6804/4159520
1947 ==== rep_scrubmap(8.2bc e1205735 from shard 29) v2 ==== 40+0+1494
(3695125937 0 865217733) 0x563092d90900 con 0x56308bf61000
2019-02-09 07:29:34.415868 7f5faf4b4700  1 --
192.168.222.202:6816/157436 --> 192.168.222.204:6804/4159520 --
osd_repop(client.171725953.0:404377591 8.9b e1205833/1205735
8:d90adab6:::rbd_data.c47f3c390c8495.000000000001934a:head v
1205833'4767322) v2 -- 0x56308ca42400 con 0
2019-02-09 07:29:34.486296 7f5faf4b4700  1 --
192.168.222.202:6816/157436 --> 192.168.222.204:6804/4159520 --
replica_scrub(pg:
8.2bc,from:0'0,to:0'0,epoch:1205833/1205735,start:8:3d4e6916:::rbd_data.a6dc2425de9600.000000000006249c:0,end:8:3d4e7434:::rbd_data.47c1b437840214.000000000003c594:0,chunky:1,deep:0,version:9,allow_preemption:1,priority=5)
v9 -- 0x56308e565340 con 0

I'd be taking a good, hard look at the network, yes.

On Sat, Feb 9, 2019 at 6:33 PM Massimo Sgaravatto
<massimo.sgaravatto@xxxxxxxxx> wrote:
>
> Thanks for your feedback !
>
> I increased debug_ms to 1/5.
>
> This is another slow request (full output from 'ceph daemon osd.5 dump_historic_ops' for this event is attached):
>
>
>         {
>             "description": "osd_op(client.171725953.0:404377591 8.9b 8:d90adab6:
> ::rbd_data.c47f3c390c8495.000000000001934a:head [set-alloc-hint object_size 4194
> 304 write_size 4194304,write 1413120~122880] snapc 0=[] ondisk+write+known_if_re
> directed e1205833)",
>             "initiated_at": "2019-02-09 07:29:34.404655",
>             "age": 387.914193,
>             "duration": 340.224154,
>             "type_data": {
>                 "flag_point": "commit sent; apply or cleanup",
>                 "client_info": {
>                     "client": "client.171725953",
>                     "client_addr": "192.168.61.66:0/4056439540",
>                     "tid": 404377591
>                 },
>                 "events": [
>                     {
>                         "time": "2019-02-09 07:29:34.404655",
>                         "event": "initiated"
>                     },
> ....
> ....
>                    {
>                         "time": "2019-02-09 07:29:34.416752",
>                         "event": "op_applied"
>                     },
>                     {
>                         "time": "2019-02-09 07:29:34.417200",
>                         "event": "sub_op_commit_rec from 14"
>                     },
>                     {
>                         "time": "2019-02-09 07:35:14.628724",
>                         "event": "sub_op_commit_rec from 29"
>                     },
>
> osd.5 has IP 192.168.222.202
> osd.14 has IP 192.168.222.203
> osd.29 has IP 192.168.222.204
>
>
> Grepping using that client id from osd.5 log as far as I can understand (please correct me if my debugging is completely wrong) the request to 5 and 14 is sent at  07:29:34:
>
> 2019-02-09 07:29:34.415808 7f5faf4b4700  1 -- 192.168.222.202:6816/157436 --> 192.168.222.203:6811/158495 -- osd_repop(client.171725953.0:404377591 8.9b e1205833/1205735 8:d90ada\
> b6:::rbd_data.c47f3c390c8495.000000000001934a:head v 1205833'4767322) v2 -- 0x56307bb61e00 con 0
> 2019-02-09 07:29:34.415868 7f5faf4b4700  1 -- 192.168.222.202:6816/157436 --> 192.168.222.204:6804/4159520 -- osd_repop(client.171725953.0:404377591 8.9b e1205833/1205735 8:d90ad\
> ab6:::rbd_data.c47f3c390c8495.000000000001934a:head v 1205833'4767322) v2 -- 0x56308ca42400 con 0
> 2019-02-09 07:29:34.417132 7f5fcf60f700  1 -- 192.168.222.202:6816/157436 <== osd.14 192.168.222.203:6811/158495 11242 ==== osd_repop_reply(client.171725953.0:404377591 8.9b e120\
> 5833/1205735) v2 ==== 111+0+0 (634943494 0 0) 0x563090642780 con 0x56308bbd0000
>
> The answer from 14 arrives immediately:
>
> 2019-02-09 07:29:34.417132 7f5fcf60f700  1 -- 192.168.222.202:6816/157436 <== osd.14 192.168.222.203:6811/158495 11242 ==== osd_repop_reply(client.171725953.0:404377591 8.9b e120\
> 5833/1205735) v2 ==== 111+0+0 (634943494 0 0) 0x563090642780 con 0x56308bbd0000
>
> while the one from 29 arrives only at 7.35:
>
> 2019-02-09 07:35:14.628614 7f5fcee0e700  1 -- 192.168.222.202:6816/157436 <== osd.29 192.168.222.204:6804/4159520 1952 ==== osd_repop_reply(client.171725953.0:404377591 8.9b e120\
> 5833/1205735) v2 ==== 111+0+0 (3804866849 0 0) 0x56308f3f2a00 con 0x56308bf61000
>
>
> In osd.29 log it looks like the request only arrives at 07.35 (and it promptly replies):
>
> 2019-02-09 07:35:14.627462 7f99972cc700  1 -- 192.168.222.204:6804/4159520 <== osd.5 192.168.222.202:6816/157436 2527 ==== osd_repop(client.171725953.0:404377591 8.9b e1205833/1205735) v2 ==== 1050+0+123635 (1225076790 0 171428115) 0x5610f5128a00 con 0x5610fc5bf000
> 2019-02-09 07:35:14.628343 7f998d6d4700  1 -- 192.168.222.204:6804/4159520 --> 192.168.222.202:6816/157436 -- osd_repop_reply(client.171725953.0:404377591 8.9b e1205833/1205735 ondisk, result = 0) v2 -- 0x5610f4a51180 con 0
>
>
> Network problems ?
>
>
> Full logs for the 3 relevant OSDs (just for that time period) is at: https://drive.google.com/drive/folders/1TG5MomMJsqVbsuFosvYokNptLufxOnPY?usp=sharing
>
>
>
> Thanks again !
> Cheers, Massimo
>
>
>
> On Fri, Feb 8, 2019 at 11:50 PM Brad Hubbard <bhubbard@xxxxxxxxxx> wrote:
>>
>> Try capturing another log with debug_ms turned up. 1 or 5 should be Ok
>> to start with.
>>
>> On Fri, Feb 8, 2019 at 8:37 PM Massimo Sgaravatto
>> <massimo.sgaravatto@xxxxxxxxx> wrote:
>> >
>> > Our Luminous ceph cluster have been worked without problems for a while, but in the last days we have been suffering from continuous slow requests.
>> >
>> > We have indeed done some changes in the infrastructure recently:
>> >
>> > - Moved OSD nodes to a new switch
>> > - Increased pg nums for a pool, to have about ~ 100 PGs/OSD (also because  we have to install new OSDs in the cluster). The output of 'ceph osd df' is attached.
>> >
>> > The problem could also be due to some ''bad' client, but in the log I don't see a clear "correlation" with specific clients or images for such blocked requests.
>> >
>> > I also tried to update to latest luminous release and latest CentOS7, but this didn't help.
>> >
>> >
>> >
>> > Attached you can find the detail of one of such slow operations which took about 266 secs (output from 'ceph daemon osd.11 dump_historic_ops').
>> > So as far as I can understand from these events:
>> >                     {
>> >                         "time": "2019-02-08 10:26:25.651728",
>> >                         "event": "op_commit"
>> >                     },
>> >                     {
>> >                         "time": "2019-02-08 10:26:25.651965",
>> >                         "event": "op_applied"
>> >                     },
>> >
>> >                   {
>> >                         "time": "2019-02-08 10:26:25.653236",
>> >                         "event": "sub_op_commit_rec from 33"
>> >                     },
>> >                     {
>> >                         "time": "2019-02-08 10:30:51.890404",
>> >                         "event": "sub_op_commit_rec from 23"
>> >                     },
>> >
>> > the problem seems with the  "sub_op_commit_rec from 23" event which took too much.
>> > So the problem is that the answer from OSD 23 took to much ?
>> >
>> >
>> > In the logs of the 2 OSD (11 and 23)in that time frame (attached) I can't find anything useful.
>> > When the problem happened the load and the usage of memory was not high in the relevant nodes.
>> >
>> >
>> > Any help to debug the issue is really appreciated ! :-)
>> >
>> > Thanks, Massimo
>> >
>> > _______________________________________________
>> > ceph-users mailing list
>> > ceph-users@xxxxxxxxxxxxxx
>> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>>
>>
>>
>> --
>> Cheers,
>> Brad



--
Cheers,
Brad
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