You could also see open sessions at the MDS server by issuing `ceph daemon
mds.XX session ls`
Regards,
Webert Lima
DevOps Engineer at MAV Tecnologia
*Belo Horizonte - Brasil*
*IRC NICK - WebertRLZ*
On Wed, Aug 8, 2018 at 5:08 AM Zhenshi Zhou <deader...@gmail.com> wrote:
> Hi, I find an old server which mounted cephfs and has the debug files.
> # cat osdc
> REQUESTS 0 homeless 0
> LINGER REQUESTS
> BACKOFFS
> # cat monc
> have monmap 2 want 3+
> have osdmap 3507
> have fsmap.user 0
> have mdsmap 55 want 56+
> fs_cluster_id -1
> # cat mdsc
> 194 mds0 getattr #10000036ae3
>
> What does it mean?
>
> Zhenshi Zhou <deader...@gmail.com> 于2018年8月8日周三 下午1:58写道：
>
>> I restarted the client server so that there's no file in that directory.
>> I will take care of it if the client hangs next time.
>>
>> Thanks
>>
>> Yan, Zheng <uker...@gmail.com> 于2018年8月8日周三 上午11:23写道：
>>
>>> On Wed, Aug 8, 2018 at 11:02 AM Zhenshi Zhou <deader...@gmail.com>
>>> wrote:
>>> >
>>> > Hi,
>>> > I check all my ceph servers and they are not mount cephfs on each of
>>> them(maybe I umount after testing). As a result, the cluster didn't
>>> encounter a memory deadlock. Besides, I check the monitoring system and the
>>> memory and cpu usage were at common level while the clients hung.
>>> > Back to my question, there must be something else cause the client
>>> hang.
>>> >
>>>
>>> Check if there are hang requests in
>>> /sys/kernel/debug/ceph/xxxx/{osdc,mdsc},
>>>
>>> > Zhenshi Zhou <deader...@gmail.com> 于2018年8月8日周三 上午4:16写道：
>>> >>
>>> >> Hi, I'm not sure if it just mounts the cephfs without using or doing
>>> any operation within the mounted directory would be affected by flushing
>>> cache. I mounted cephfs on osd servers only for testing and then left it
>>> there. Anyway I will umount it.
>>> >>
>>> >> Thanks
>>> >>
>>> >> John Spray <jsp...@redhat.com>于2018年8月8日 周三03:37写道：
>>> >>>
>>> >>> On Tue, Aug 7, 2018 at 5:42 PM Reed Dier <reed.d...@focusvq.com>
>>> wrote:
>>> >>> >
>>> >>> > This is the first I am hearing about this as well.
>>> >>>
>>> >>> This is not a Ceph-specific thing -- it can also affect similar
>>> >>> systems like Lustre.
>>> >>>
>>> >>> The classic case is when under some memory pressure, the kernel tries
>>> >>> to free memory by flushing the client's page cache, but doing the
>>> >>> flush means allocating more memory on the server, making the memory
>>> >>> pressure worse, until the whole thing just seizes up.
>>> >>>
>>> >>> John
>>> >>>
>>> >>> > Granted, I am using ceph-fuse rather than the kernel client at
>>> this point, but that isn’t etched in stone.
>>> >>> >
>>> >>> > Curious if there is more to share.
>>> >>> >
>>> >>> > Reed
>>> >>> >
>>> >>> > On Aug 7, 2018, at 9:47 AM, Webert de Souza Lima <
>>> webert.b...@gmail.com> wrote:
>>> >>> >
>>> >>> >
>>> >>> > Yan, Zheng <uker...@gmail.com> 于2018年8月7日周二 下午7:51写道：
>>> >>> >>
>>> >>> >> On Tue, Aug 7, 2018 at 7:15 PM Zhenshi Zhou <deader...@gmail.com>
>>> wrote:
>>> >>> >> this can cause memory deadlock. you should avoid doing this
>>> >>> >>
>>> >>> >> > Yan, Zheng <uker...@gmail.com>于2018年8月7日 周二19:12写道：
>>> >>> >> >>
>>> >>> >> >> did you mount cephfs on the same machines that run ceph-osd?
>>> >>> >> >>
>>> >>> >
>>> >>> >
>>> >>> > I didn't know about this. I run this setup in production. :P
>>> >>> >
>>> >>> > Regards,
>>> >>> >
>>> >>> > Webert Lima
>>> >>> > DevOps Engineer at MAV Tecnologia
>>> >>> > Belo Horizonte - Brasil
>>> >>> > IRC NICK - WebertRLZ
>>> >>> >
>>> >>> > _______________________________________________
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>>> >>> > ceph-users@lists.ceph.com
>>> >>> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>>> >>> >
>>> >>> >
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>>> >
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>>>
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