Re: "ceph fs" commands hang forever and kill monitors

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On Thu, Sep 28, 2017 at 11:51 AM, Richard Hesketh
<richard.hesketh@xxxxxxxxxxxx> wrote:
> On 27/09/17 19:35, John Spray wrote:
>> On Wed, Sep 27, 2017 at 1:18 PM, Richard Hesketh
>> <richard.hesketh@xxxxxxxxxxxx> wrote:
>>> On 27/09/17 12:32, John Spray wrote:
>>>> On Wed, Sep 27, 2017 at 12:15 PM, Richard Hesketh
>>>> <richard.hesketh@xxxxxxxxxxxx> wrote:
>>>>> As the subject says... any ceph fs administrative command I try to run hangs forever and kills monitors in the background - sometimes they come back, on a couple of occasions I had to manually stop/restart a suffering mon. Trying to load the filesystem tab in the ceph-mgr dashboard dumps an error and can also kill a monitor. However, clients can mount the filesystem and read/write data without issue.
>>>>>
>>>>> Relevant excerpt from logs on an affected monitor, just trying to run 'ceph fs ls':
>>>>>
>>>>> 2017-09-26 13:20:50.716087 7fc85fdd9700  0 mon.vm-ds-01@0(leader) e19 handle_command mon_command({"prefix": "fs ls"} v 0) v1
>>>>> 2017-09-26 13:20:50.727612 7fc85fdd9700  0 log_channel(audit) log [DBG] : from='client.? 10.10.10.1:0/2771553898' entity='client.admin' cmd=[{"prefix": "fs ls"}]: dispatch
>>>>> 2017-09-26 13:20:50.950373 7fc85fdd9700 -1 /build/ceph-12.2.0/src/osd/OSDMap.h: In function 'const string& OSDMap::get_pool_name(int64_t) const' thread 7fc85fdd9700 time 2017-09-26 13:20:50.727676
>>>>> /build/ceph-12.2.0/src/osd/OSDMap.h: 1176: FAILED assert(i != pool_name.end())
>>>>>
>>>>>  ceph version 12.2.0 (32ce2a3ae5239ee33d6150705cdb24d43bab910c) luminous (rc)
>>>>>  1: (ceph::__ceph_assert_fail(char const*, char const*, int, char const*)+0x102) [0x55a8ca0bb642]
>>>>>  2: (()+0x48165f) [0x55a8c9f4165f]
>>>>>  3: (MDSMonitor::preprocess_command(boost::intrusive_ptr<MonOpRequest>)+0x1d18) [0x55a8ca047688]
>>>>>  4: (MDSMonitor::preprocess_query(boost::intrusive_ptr<MonOpRequest>)+0x2a8) [0x55a8ca048008]
>>>>>  5: (PaxosService::dispatch(boost::intrusive_ptr<MonOpRequest>)+0x700) [0x55a8c9f9d1b0]
>>>>>  6: (Monitor::handle_command(boost::intrusive_ptr<MonOpRequest>)+0x1f93) [0x55a8c9e63193]
>>>>>  7: (Monitor::dispatch_op(boost::intrusive_ptr<MonOpRequest>)+0xa0e) [0x55a8c9e6a52e]
>>>>>  8: (Monitor::_ms_dispatch(Message*)+0x6db) [0x55a8c9e6b57b]
>>>>>  9: (Monitor::ms_dispatch(Message*)+0x23) [0x55a8c9e9a053]
>>>>>  10: (DispatchQueue::entry()+0xf4a) [0x55a8ca3b5f7a]
>>>>>  11: (DispatchQueue::DispatchThread::entry()+0xd) [0x55a8ca16bc1d]
>>>>>  12: (()+0x76ba) [0x7fc86b3ac6ba]
>>>>>  13: (clone()+0x6d) [0x7fc869bd63dd]
>>>>>  NOTE: a copy of the executable, or `objdump -rdS <executable>` is needed to interpret this.
>>>>>
>>>>> I'm running Luminous. The cluster and FS have been in service since Hammer and have default data/metadata pool names. I discovered the issue after attempting to enable directory sharding.
>>>>
>>>> Well that's not good...
>>>>
>>>> The assertion is because your FSMap is referring to a pool that
>>>> apparently no longer exists in the OSDMap.  This should be impossible
>>>> in current Ceph (we forbid removing pools if they're in use), but
>>>> could perhaps have been caused in an earlier version of Ceph when it
>>>> was possible to remove a pool even if CephFS was referring to it?
>>>>
>>>> Alternatively, perhaps something more severe is going on that's
>>>> causing your mons to see a wrong/inconsistent view of the world.  Has
>>>> the cluster ever been through any traumatic disaster recovery type
>>>> activity involving hand-editing any of the cluster maps?  What
>>>> intermediate versions has it passed through on the way from Hammer to
>>>> Luminous?
>>>>
>>>> Opened a ticket here: http://tracker.ceph.com/issues/21568
>>>>
>>>> John
>>>
>>> I've reviewed my notes (i.e. I've grepped my IRC logs); I actually inherited this cluster from a colleague who left shortly after I joined, so unfortunately there is some of its history I cannot fill in.
>>>
>>> Turns out the cluster actually predates Firefly. Looking at dates my suspicion is that it went Emperor -> Firefly -> Giant -> Hammer. I inherited it at Hammer, and took it Hammer -> Infernalis -> Jewel -> Luminous myself. I know I did make sure to do the tmap_upgrade step on cephfs but can't remember if I did it at Infernalis or Jewel.
>>>
>>> Infernalis was a tricky upgrade; the attempt was aborted once after the first set of OSDs didn't come back up after upgrade (had to remove/downgrade and readd), and setting sortbitwise as the documentation suggested after a successful second attempt caused everything to break and degrade slowly until it was unset and recovered. Never had disaster recovery involve mucking around with the pools while I was administrating it, but unfortunately I cannot speak for the cluster's pre-Hammer history. The only pools I have removed were ones I created temporarily for testing crush rules/benchmarking.
>>
>> OK, so it sounds like a cluster with an interesting history and some
>> stories to tell :-)
>>
>>> I have hand-edited the crush map (extract, decompile, modify, recompile, inject) at times because I found it more convenient for creating new crush rules than using the CLI tools, but not the OSD map.
>>>
>>> Why would the cephfs have been referring to other pools?
>>
>> A filesystem can have more than one data pool, they're added at
>> runtime with add_data_pool/rm_data_pool commands.  In old versions of
>> the code, someone could add a data pool, then delete the pool, and
>> forget to do rm_data_pool.
>>
>> So, next step is to try and actually get the FSMap out of the
>> monitor's store to see if that's really what's happening --
>> unfortunately when checking how to do that I realise we missed
>> updating the human readable output of ceph-monstore-tool when adding
>> multi-filesystem support... so here's how to get it out in binary form
>> and then decode it separately:
>>
>> ceph-monstore-tool /var/lib/ceph/<wherever...> get mdsmap > fsmap.bin
>> ceph-dencoder import fsmap.bin type FSMap decode dump_json
>>
>> If the simple theory is correct then you'll see something referenced
>> in one of the pool/pools fields that doesn't really exist.
>>
>> John
>
> After some effort working out which package provides ceph-monstore-tool in ubuntu xenial (turns out it's ceph-test, but I now have every ceph*[-dbg] package installed on my admin node)... you are indeed correct:
>
> root@vm-ds-01:~/ceph-conf# systemctl stop ceph-mon.target
> root@vm-ds-01:~/ceph-conf# ceph-monstore-tool /var/lib/ceph/mon/ceph-vm-ds-01/ get mdsmap > fsmap.bin
> root@vm-ds-01:~/ceph-conf# systemctl start ceph-mon.target
> root@vm-ds-01:~/ceph-conf# ceph-dencoder import fsmap.bin type FSMap decode dump_json
> ...
>                 "data_pools": [
>                     0,
>                     5,
>                     7,
>                     8
>                 ],
> ...
> root@vm-ds-01:~/ceph-conf# ceph osd lspools
> 0 data,1 metadata,8 one,22 ssd,24 .rgw.root,25 default.rgw.control,26 default.rgw.data.root,27 default.rgw.gc,28 default.rgw.log,29 default.rgw.users.uid,30 default.rgw.users.keys,31 default.rgw.buckets.index,32 default.rgw.buckets.non-ec,33 default.rgw.buckets.data,
>
> The large gaps in the pool numbers are a good sign someone did a lot of experimenting. Turns out the fs does reference pools that don't exist, plus one that does but shouldn't be in the fs. A quick application of `ceph fs rm_data_pool` and ceph fs commands now return without issue:
>
> root@vm-ds-01:~/ceph-conf# ceph fs rm_data_pool cephfs one
> removed data pool 8 from fsmap
> root@vm-ds-01:~/ceph-conf# ceph fs rm_data_pool cephfs 5
> removed data pool 5 from fsmap
> root@vm-ds-01:~/ceph-conf# ceph fs rm_data_pool cephfs 7
> removed data pool 7 from fsmap
> root@vm-ds-01:~/ceph-conf# ceph fs ls
> name: cephfs, metadata pool: metadata, data pools: [data ]
>
> And I can finally do what I was trying to do three days ago which prompted all this:
>
> root@vm-ds-01:~/ceph-conf# ceph fs set cephfs allow_dirfrags 1
> enabled directory fragmentation

Fantastic, have fun with your huge directories :-D

John

> Thanks!
> Rich
>
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