What happens when a storage node loses its cluster network but not it's
public network is that all other osss on the cluster see that it's down and
report that to the mons, but the node call still talk to the mons telling
the mons that it is up and in fact everything else is down.

The setting osd _min_reporters (I think that's the name of it off the top
of my head) is designed to help with this scenario. It's default is 1 which
means any osd on either side of the network problem will be trusted by the
mons to mark osds down. What you want to do with this seeing is to set it
to at least 1 more than the number of osds in your failure domain. If the
failure domain is host and each node has 32 osds, then setting it to 33
will prevent a full problematic node from being able to cause havoc.

The osds will still try to mark themselves as up and this will still cause
problems for read until the osd process stops or the network comes back up.
There might be a seeing for how long an odd will try telling the mons it's
up, but this isn't really a situation I've come across after initial
testing and installation of nodes.

On Tue, May 22, 2018, 1:47 AM nokia ceph <[email protected]> wrote:

> Hi Ceph users,
>
> We have a cluster with 5 node (67 disks) and EC 4+1 configuration and
> min_size set as 4.
> Ceph version : 12.2.5
> While executing one of our resilience usecase , making private interface
> down on one of the node, till kraken we saw less outage in rados (60s) .
>
> Now with luminous, we could able to see rados read/write outage for more
> than 200s . In the logs we could able to see that peer OSDs inform that one
> of the node OSDs are down however the OSDs  defend like it is wrongly
> marked down and does not move to down state for long time.
>
> 2018-05-22 05:37:17.871049 7f6ac71e6700  0 log_channel(cluster) log [WRN]
> : Monitor daemon marked osd.1 down, but it is still running
> 2018-05-22 05:37:17.871072 7f6ac71e6700  0 log_channel(cluster) log [DBG]
> : map e35690 wrongly marked me down at e35689
> 2018-05-22 05:37:17.878347 7f6ac71e6700  0 osd.1 35690 crush map has
> features 1009107927421960192, adjusting msgr requires for osds
> 2018-05-22 05:37:18.296643 7f6ac71e6700  0 osd.1 35691 crush map has
> features 1009107927421960192, adjusting msgr requires for osds
>
>
> Only when all 67 OSDs are move to down state , the read/write traffic is
> resumed.
>
> Could you please help us in resolving this issue and if it is bug , we
> will create corresponding ticket.
>
> Thanks,
> Muthu
> _______________________________________________
> ceph-users mailing list
> [email protected]
> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>
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