Ceph » RADOS

Problem description:

Not using sections to declare ceph monitors results in monitors listening on the public_cluster subnet where it should listen on the mon_host address.
See the following ceph.conf:

[global]
fsid = 2a1e38b5-2b5b-4e7a-8443-3b184d1440cf
max open files = 131072
mon initial members = ceph-mon0
mon host = 172.16.0.10
public network = 192.168.42.0/24
cluster network = 192.168.43.0/24

When running a monitor service we can see that:

2016-11-24 13:00:58.585320 7ff39afad580  0 mon.ceph-mon0 does not exist in monmap, will attempt to join an existing cluster
2016-11-24 13:00:58.585449 7ff39afad580  0 using public_addr 192.168.42.10:0/0 -> 192.168.42.10:6789/0
2016-11-24 13:00:58.585487 7ff39afad580  0 starting mon.ceph-mon0 rank -1 at 192.168.42.10:6789/0 mon_data /var/lib/ceph/mon/ceph-ceph-mon0 fsid 2a1e38b5-2b5b-4e7a-8443-3b184d1440cf

Moreover:

root@ceph-mon0:~# netstat -tpln | grep ceph-mon
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 192.168.42.10:6789      0.0.0.0:*               LISTEN      16242/ceph-mon

Excepted result:

Since mon_host is declared the monitor service should listen on that address instead of the public_network.

This allows us to build setup where we have 3 distincts networks:

• 1 monitor network
• 1 public_network
• 1 cluster_network

Voilà.
Thanks!