Try running gstack on the ceph mgr process when it is frozen?
This could be a name resolution problem, as you suspect. Maybe gstack will show where the process is 'stuck'and this might be a call to your name resolution service.
On Tue, 27 Aug 2019 at 14:25, Jake Grimmett <jog@xxxxxxxxxxxxxxxxx> wrote:
Whoops, I'm running Scientific Linux 7.6, going to upgrade to 7.7. soon...
thanks
Jake
On 8/27/19 2:22 PM, Jake Grimmett wrote:
> Hi Reed,
>
> That exactly matches what I'm seeing:
>
> when iostat is working OK, I see ~5% CPU use by ceph-mgr
> and when iostat freezes, ceph-mgr CPU increases to 100%
>
> regarding OS, I'm using Scientific Linux 7.7
> Kernel 3.10.0-957.21.3.el7.x86_64
>
> I'm not sure if the mgr initiates scrubbing, but if so, this could be
> the cause of the "HEALTH_WARN 20 pgs not deep-scrubbed in time" that we see.
>
> Anyhow, many thanks for your input, please let me know if you have
> further ideas :)
>
> best,
>
> Jake
>
> On 8/27/19 2:01 PM, Reed Dier wrote:
>> Curious what dist you're running on, as I've been having similar issues with instability in the mgr as well, curious if any similar threads to pull at.
>>
>> While the iostat command is running, is the active mgr using 100% CPU in top?
>>
>> Reed
>>
>>> On Aug 27, 2019, at 6:41 AM, Jake Grimmett <jog@xxxxxxxxxxxxxxxxx> wrote:
>>>
>>> Dear All,
>>>
>>> We have a new Nautilus (14.2.2) cluster, with 328 OSDs spread over 40 nodes.
>>>
>>> Unfortunately "ceph iostat" spends most of it's time frozen, with
>>> occasional periods of working normally for less than a minute, then
>>> freeze again for a couple of minutes, then come back to life, and so so
>>> on...
>>>
>>> No errors are seen on screen, unless I press CTRL+C when iostat is stalled:
>>>
>>> [root@ceph-s3 ~]# ceph iostat
>>> ^CInterrupted
>>> Traceback (most recent call last):
>>> File "/usr/bin/ceph", line 1263, in <module>
>>> retval = main()
>>> File "/usr/bin/ceph", line 1194, in main
>>> verbose)
>>> File "/usr/bin/ceph", line 619, in new_style_command
>>> ret, outbuf, outs = do_command(parsed_args, target, cmdargs,
>>> sigdict, inbuf, verbose)
>>> File "/usr/bin/ceph", line 593, in do_command
>>> return ret, '', ''
>>> UnboundLocalError: local variable 'ret' referenced before assignment
>>>
>>> Observations:
>>>
>>> 1) This problem does not seem to be related to load on the cluster.
>>>
>>> 2) When iostat is stalled the dashboard is also non-responsive, if
>>> iostat is working, the dashboard also works.
>>>
>>> Presumably the iostat and dashboard problems are due to the same
>>> underlying fault? Perhaps a problem with the mgr?
>>>
>>>
>>> 3) With iostat working, tailing /var/log/ceph/ceph-mgr.ceph-s3.log
>>> shows:
>>>
>>> 2019-08-27 09:09:56.817 7f8149834700 0 log_channel(audit) log [DBG] :
>>> from='client.4120202 -' entity='client.admin' cmd=[{"width": 95,
>>> "prefix": "iostat", "poll": true, "target": ["mgr", ""], "print_header":
>>> false}]: dispatch
>>>
>>> 4) When iostat isn't working, we see no obvious errors in the mgr log.
>>>
>>> 5) When the dashboard is not working, mgr log sometimes shows:
>>>
>>> 2019-08-27 09:18:18.810 7f813e533700 0 mgr[dashboard]
>>> [::ffff:10.91.192.36:43606] [GET] [500] [2.724s] [jake] [1.6K]
>>> /api/health/minimal
>>> 2019-08-27 09:18:18.887 7f813e533700 0 mgr[dashboard] ['{"status": "500
>>> Internal Server Error", "version": "3.2.2", "detail": "The server
>>> encountered an unexpected condition which prevented it from fulfilling
>>> the request.", "traceback": "Traceback (most recent call last):\\n File
>>> \\"/usr/lib/python2.7/site-packages/cherrypy/_cprequest.py\\", line 656,
>>> in respond\\n response.body = self.handler()\\n File
>>> \\"/usr/lib/python2.7/site-packages/cherrypy/lib/encoding.py\\", line
>>> 188, in __call__\\n self.body = self.oldhandler(*args, **kwargs)\\n
>>> File \\"/usr/lib/python2.7/site-packages/cherrypy/_cptools.py\\", line
>>> 221, in wrap\\n return self.newhandler(innerfunc, *args, **kwargs)\\n
>>> File \\"/usr/share/ceph/mgr/dashboard/services/exception.py\\", line
>>> 88, in dashboard_exception_handler\\n return handler(*args,
>>> **kwargs)\\n File
>>> \\"/usr/lib/python2.7/site-packages/cherrypy/_cpdispatch.py\\", line 34,
>>> in __call__\\n return self.callable(*self.args, **self.kwargs)\\n
>>> File \\"/usr/share/ceph/mgr/dashboard/controllers/__init__.py\\", line
>>> 649, in inner\\n ret = func(*args, **kwargs)\\n File
>>> \\"/usr/share/ceph/mgr/dashboard/controllers/health.py\\", line 192, in
>>> minimal\\n return self.health_minimal.all_health()\\n File
>>> \\"/usr/share/ceph/mgr/dashboard/controllers/health.py\\", line 51, in
>>> all_health\\n result[\'pools\'] = self.pools()\\n File
>>> \\"/usr/share/ceph/mgr/dashboard/controllers/health.py\\", line 167, in
>>> pools\\n pools = CephService.get_pool_list_with_stats()\\n File
>>> \\"/usr/share/ceph/mgr/dashboard/services/ceph_service.py\\", line 124,
>>> in get_pool_list_with_stats\\n \'series\': [i for i in
>>> stat_series]\\nRuntimeError: deque mutated during iteration\\n"}']
>>>
>>>
>>> 6) IPV6 is normally disabled on our machines at the kernel level, via
>>> grubby --update-kernel=ALL --args="ipv6.disable=1"
>>>
>>> This was done as 'disabling ipv6' interfered with the dashboard (giving
>>> "HEALTH_ERR Module 'dashboard' has failed: error('No socket could be
>>> created',) we re-enabling ipv6 on the mgr nodes only to fix this.
>>>
>>>
>>> Ideas...?
>>>
>>> Should ipv6 be enabled, even if not configured, on all ceph nodes?
>>>
>>> Any ideas on fixing this gratefully received!
>>>
>>> many thanks
>>>
>>> Jake
>>>
>>> --
>>> MRC Laboratory of Molecular Biology
>>> Francis Crick Avenue,
>>> Cambridge CB2 0QH, UK.
>>>
>>> _______________________________________________
>>> ceph-users mailing list
>>> ceph-users@xxxxxxxxxxxxxx
>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>>
>
>
--
MRC Laboratory of Molecular Biology
Francis Crick Avenue,
Cambridge CB2 0QH, UK.
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