Dear Reed,

yes, also the balancer is on for me - but the instabilities vanished as soon as I turned off device health metrics. 

Cheers,
Oliver

Am 02.11.19 um 17:31 schrieb Reed Dier:

Do you also have the balancer module on?

I experienced extremely bad stability issues where the MGRs would silently die with the balancer module on.
And by on, I mean 'active:true` by way of `ceph balancer on`.

Once I disabled the automatic balancer, it seemed to become much more stable.

I can still manually run the balancer without issues (except for one pool), but the balancer is what appeared to be my big driver of instability.

Reed

On Nov 2, 2019, at 11:24 AM, Oliver Freyermuth <freyermuth@physik.uni-bonn.de> wrote:

Hi Thomas,

indeed, I also had the dashboard open at these times - but right now, after disabling device health metrics,
I can not retrigger it even when playing wildly on the dashboard. 

So I'll now reenable health metrics and try to retrigger the issue with cranked up debug levels as Sage suggested. 
Maybe in your case, if you can stand mgr failures, this would also be interesting to get the dashboard issue debugged? 

Cheers,
Oliver

Am 02.11.19 um 08:23 schrieb Thomas:

Hi Oliver,

I experienced a situation where MGRs "goes crazy", means MGR was active but not working.
In the logs of the standby MGR nodes I found an error (after restarting service) that pointed to Ceph Dashboard.

Since disabling the dashboard my MGRs are stable again.

Regards
Thomas

Am 02.11.2019 um 02:48 schrieb Oliver Freyermuth:

Dear Cephers,

interestingly, after:
  ceph device monitoring off
the mgrs seem to be stable now - the active one still went silent a few minutes later,
but the standby took over and was stable, and restarting the broken one, it's now stable since an hour, too,
so probably, a restart of the mgr is needed after disabling device monitoring to get things stable again.

So it seems to be caused by a problem with the device health metrics. In case this is a red herring and mgrs become instable again in the next days,
I'll let you know.

Cheers,
    Oliver

Am 01.11.19 um 23:09 schrieb Oliver Freyermuth:

Dear Cephers,

this is a 14.2.4 cluster with device health metrics enabled - since about a day, all mgr daemons go "silent" on me after a few hours, i.e. "ceph -s" shows:

   cluster:
     id:     269cf2b2-7e7c-4ceb-bd1b-a33d915ceee9
     health: HEALTH_WARN
             no active mgr
             1/3 mons down, quorum mon001,mon002
     services:
     mon:        3 daemons, quorum mon001,mon002 (age 57m), out of quorum: mon003
     mgr:        no daemons active (since 56m)
     ...
(the third mon has a planned outage and will come back in a few days)

Checking the logs of the mgr daemons, I find some "reset" messages at the time when it goes "silent", first for the first mgr:

2019-11-01 21:34:40.286 7f2df6a6b700  0 log_channel(cluster) log [DBG] : pgmap v1798: 1585 pgs: 1585 active+clean; 1.1 TiB data, 2.3 TiB used, 136 TiB / 138 TiB avail
2019-11-01 21:34:41.458 7f2e0d59b700  0 client.0 ms_handle_reset on v2:10.160.16.1:6800/401248
2019-11-01 21:34:42.287 7f2df6a6b700  0 log_channel(cluster) log [DBG] : pgmap v1799: 1585 pgs: 1585 active+clean; 1.1 TiB data, 2.3 TiB used, 136 TiB / 138 TiB avail

and a bit later, on the standby mgr:

2019-11-01 22:18:14.892 7f7bcc8ae700  0 log_channel(cluster) log [DBG] : pgmap v1798: 1585 pgs: 166 active+clean+snaptrim, 858 active+clean+snaptrim_wait, 561 active+clean; 1.1 TiB data, 2.3 TiB used, 136 TiB / 138 TiB avail
2019-11-01 22:18:16.022 7f7be9e72700  0 client.0 ms_handle_reset on v2:10.160.16.2:6800/352196
2019-11-01 22:18:16.893 7f7bcc8ae700  0 log_channel(cluster) log [DBG] : pgmap v1799: 1585 pgs: 166 active+clean+snaptrim, 858 active+clean+snaptrim_wait, 561 active+clean; 1.1 TiB data, 2.3 TiB used, 136 TiB / 138 TiB avail

Interestingly, the dashboard still works, but presents outdated information, and for example zero I/O going on.
I believe this started to happen mainly after the third mon went into the known downtime, but I am not fully sure if this was the trigger, since the cluster is still growing.
It may also have been the addition of 24 more OSDs.

I also find other messages in the mgr logs which seem problematic, but I am not sure they are related:
------------------------------
2019-11-01 21:17:09.849 7f2df4266700  0 mgr[devicehealth] Error reading OMAP: [errno 22] Failed to operate read op for oid
Traceback (most recent call last):
   File "/usr/share/ceph/mgr/devicehealth/module.py", line 396, in put_device_metrics
     ioctx.operate_read_op(op, devid)
   File "rados.pyx", line 516, in rados.requires.wrapper.validate_func (/home/jenkins-build/build/workspace/ceph-build/ARCH/x86_64/AVAILABLE_ARCH/x86_64/AVAILABLE_DIST/centos7/DIST/centos7/MACHINE_SIZE/huge/release/14.2.4/rpm/el7/BUIL
D/ceph-14.2.4/build/src/pybind/rados/pyrex/rados.c:4721)
   File "rados.pyx", line 3474, in rados.Ioctx.operate_read_op (/home/jenkins-build/build/workspace/ceph-build/ARCH/x86_64/AVAILABLE_ARCH/x86_64/AVAILABLE_DIST/centos7/DIST/centos7/MACHINE_SIZE/huge/release/14.2.4/rpm/el7/BUILD/ceph-14.2.4/build/src/pybind/rados/pyrex/rados.c:36554)
InvalidArgumentError: [errno 22] Failed to operate read op for oid
------------------------------
or:
------------------------------
2019-11-01 21:33:53.977 7f7bd38bc700  0 mgr[devicehealth] Fail to parse JSON result from daemon osd.51 ()
2019-11-01 21:33:53.978 7f7bd38bc700  0 mgr[devicehealth] Fail to parse JSON result from daemon osd.52 ()
2019-11-01 21:33:53.979 7f7bd38bc700  0 mgr[devicehealth] Fail to parse JSON result from daemon osd.53 ()
------------------------------

The reason why I am cautious about the health metrics is that I observed a crash when trying to query them:
------------------------------
2019-11-01 20:21:23.661 7fa46314a700  0 log_channel(audit) log [DBG] : from='client.174136 -' entity='client.admin' cmd=[{"prefix": "device get-health-metrics", "devid": "osd.11", "target": ["mgr", ""]}]: dispatch
2019-11-01 20:21:23.661 7fa46394b700  0 mgr[devicehealth] handle_command
2019-11-01 20:21:23.663 7fa46394b700 -1 *** Caught signal (Segmentation fault) **
  in thread 7fa46394b700 thread_name:mgr-fin

  ceph version 14.2.4 (75f4de193b3ea58512f204623e6c5a16e6c1e1ba) nautilus (stable)
  1: (()+0xf5f0) [0x7fa488cee5f0]
  2: (PyEval_EvalFrameEx()+0x1a9) [0x7fa48aeb50f9]
  3: (PyEval_EvalFrameEx()+0x67bd) [0x7fa48aebb70d]
  4: (PyEval_EvalFrameEx()+0x67bd) [0x7fa48aebb70d]
  5: (PyEval_EvalFrameEx()+0x67bd) [0x7fa48aebb70d]
  6: (PyEval_EvalCodeEx()+0x7ed) [0x7fa48aebe08d]
  7: (()+0x709c8) [0x7fa48ae479c8]
  8: (PyObject_Call()+0x43) [0x7fa48ae22ab3]
  9: (()+0x5aaa5) [0x7fa48ae31aa5]
  10: (PyObject_Call()+0x43) [0x7fa48ae22ab3]
  11: (()+0x4bb95) [0x7fa48ae22b95]
  12: (PyObject_CallMethod()+0xbb) [0x7fa48ae22ecb]
  13: (ActivePyModule::handle_command(std::map<std::string, boost::variant<std::string, bool, long, double, std::vector<std::string, std::allocator<std::string> >, std::vector<long, std::allocator<long> >, std::vector<double, std::allocator<double> > >, std::less<void>, std::allocator<std::pair<std::string const, boost::variant<std::string, bool, long, double, std::vector<std::string, std::allocator<std::string> >, std::vector<long, std::allocator<long> >, std::vector<double, std::allocator<double> > > > > > const&, ceph::buffer::v14_2_0::list const&, std::basic_stringstream<char, std::char_traits<char>, std::allocator<char> >*, std::basic_stringstream<char, std::char_traits<char>, std::allocator<char> >*)+0x20e) [0x55c3c1fefc5e]
  14: (()+0x16c23d) [0x55c3c204023d]
  15: (FunctionContext::finish(int)+0x2c) [0x55c3c2001eac]
  16: (Context::complete(int)+0x9) [0x55c3c1ffe659]
  17: (Finisher::finisher_thread_entry()+0x156) [0x7fa48b439cc6]
  18: (()+0x7e65) [0x7fa488ce6e65]
  19: (clone()+0x6d) [0x7fa48799488d]
  NOTE: a copy of the executable, or `objdump -rdS <executable>` is needed to interpret this.
------------------------------

I have issued:
ceph device monitoring off
for now and will keep waiting to see if mgrs go silent again. If there are any better ideas or this issue is known, let me know.

Cheers,
    Oliver

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