[ceph-users] How to debug problem in MDS ?

Florent B florent at coppint.com
Wed Oct 17 00:01:37 PDT 2018


Hi,
I'm not running multiple active MDS (1 active & 7 standby).
I know about debug_mds 20, is it the only log you need to see bugs ?

On 16/10/2018 18:32, Sergey Malinin wrote:
> Are you running multiple active MDS daemons?
> On MDS host issue "ceph-daemon mds.X config set debug_mds 20" for maximum logging verbosity.
>
>> On 16.10.2018, at 19:23, Florent B <florent at coppint.com> wrote:
>>
>> Hi,
>>
>> A few months ago I sent a message to that list about a problem with a
>> Ceph + Dovecot setup.
>>
>> Bug disappeared and I didn't answer to the thread.
>>
>> Now the bug has come again (Luminous up-to-date cluster + Dovecot
>> up-to-date + Debian Stretch up-to-date).
>>
>> I know how to reproduce it, but it seems very related to my user's
>> Dovecot data (few GB) and is related to file locking system (bug occurs
>> when I set locking method to "fcntl" or "flock" in Dovecot, but not with
>> "dotlock".
>>
>> It ends to a unresponsive MDS (100% CPU hang, switching to another MDS
>> but always staying at 100% CPU usage). I can't even use the admin socket
>> when MDS is hanged.
>>
>> I would like to know *exactly* which information do you need to
>> investigate that bug ? (which commands, when, how to report large log
>> files...)
>>
>> Thank you.
>>
>> Florent
>>
>>
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>> ceph-users at lists.ceph.com
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