# Minimum\_master\_nodes prevent nodes from joining the cluster **URL:** \ **Category:** Elasticsearch\ **Created:** [August 2, 2011, 8:52am UTC](https://discuss.elastic.co/t/minimum-master-nodes-prevent-nodes-from-joining-the-cluster/5026 "2011-08-02T08:52:31Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Michel\_Conrad](https://avatars.discourse-cdn.com/v4/letter/m/5e9695/32.png) [@Michel\_Conrad](https://discuss.elastic.co/u/Michel_Conrad)\ **Post date:** [August 2, 2011, 8:52am UTC](https://discuss.elastic.co/t/minimum-master-nodes-prevent-nodes-from-joining-the-cluster/5026/1 "2011-08-02T08:52:31Z")
Hi, Thanks Shay for the extensive debugging yesterday on IRC. Everything seems much clearer now, but I think I found a situation where the cluster joining does not work as expected. I got the following situation during startup: minimum\_master\_nodes set to 3 master:true on 5 nodes, master:false on the other nodes. unicast discovery with hosts set to the 5 nodes that can become master. During the initial cluster everything works fine, a master is elected and the other nodes join the cluster. If I remove a non-master node from cluster, then try to join again the node does not join anymore. It only gets a ping response from the elected master and does not join the cluster. I suspect its because minimum\_master\_nodes is set to 3 and the unelected masters are somehow not responding to the ping. If I restart another node, the first node gets a ping response from the master (with master=true, [master=Cerberus...] and from the other node that tries to join the cluster (with master=false, master [null]). Still not joining any cluster. Only if I set minimum\_master\_nodes to 1 the node joins the cluster, but I thought that I wanted that the node can only join a cluster with 3 master nodes, to prevent split-brains. Or does it already prevent split-brains if I set minimum\_master\_nodes to 3 for the master:true nodes, and minimum\_master\_nodes to 1 for the master:false nodes? The only thing I suspect is that if I restart one of the 5 master:true nodes, that one also cannot join the cluster again. Best, Michel ---
**Author:** ![Michel\_Conrad](https://avatars.discourse-cdn.com/v4/letter/m/5e9695/32.png) [@Michel\_Conrad](https://discuss.elastic.co/u/Michel_Conrad)\ **Post date:** [August 2, 2011, 10:14am UTC](https://discuss.elastic.co/t/minimum-master-nodes-prevent-nodes-from-joining-the-cluster/5026/2 "2011-08-02T10:14:24Z")
Hi, changing the configuration file solved the joining issue: When the hosts are comma separated and there is a whitespace after the comma, the debug message prints correctly: [DEBUG][discovery.zen.ping.unicast] [Jackson Arvad] using initial hosts [192.168.5.1[9300], 192.168.5.2[9300], 192.168.5.3[9300], 192.168.5.4[9300], 192.168.5.5[9300]] But only the first host is being used, the other four give an java.nio.channels.UnresolvedAddressException on the netty layer. I think it would be helpful if the addresses would be trimmed before being passed to netty or if it would be possible to give a warning in order to avoid similar errors in the future. Regards, Michel On Tue, Aug 2, 2011 at 10:52 AM, Michel Conrad [michel.conrad@trendiction.com](mailto:michel.conrad@trendiction.com) wrote: > Hi, > Thanks Shay for the extensive debugging yesterday on IRC. > Everything seems much clearer now, but I think I found a situation > where the cluster joining > does not work as expected. > > I got the following situation during startup: > > minimum\_master\_nodes set to 3 > master:true on 5 nodes, > master:false on the other nodes. > unicast discovery with hosts set to the 5 nodes that can become master. > > During the initial cluster everything works fine, a master is elected > and the other nodes join the cluster. > > If I remove a non-master node from cluster, then try to join again the > node does not join anymore. > It only gets a ping response from the elected master and does not join > the cluster. I suspect its because minimum\_master\_nodes is > set to 3 and the unelected masters are somehow not responding to the ping. > > If I restart another node, the first node gets a ping response from > the master (with master=true, [master=Cerberus...] and from the other > node that tries to join the cluster (with master=false, master > [null]). Still not joining any cluster. > > Only if I set minimum\_master\_nodes to 1 the node joins the cluster, > but I thought that I wanted that the node > can only join a cluster with 3 master nodes, to prevent split-brains. > Or does it already prevent split-brains if I > set minimum\_master\_nodes to 3 for the master:true nodes, and > minimum\_master\_nodes to 1 for the master:false nodes? > The only thing I suspect is that if I restart one of the 5 master:true > nodes, that one also cannot join the cluster again. > > Best, > Michel ---
**Author:** ![kimchy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/kimchy/32/44952_2.png) [@kimchy](https://discuss.elastic.co/u/kimchy)\ **Post date:** [August 2, 2011, 10:30am UTC](https://discuss.elastic.co/t/minimum-master-nodes-prevent-nodes-from-joining-the-cluster/5026/3 "2011-08-02T10:30:52Z")
:).., that explains a lot of the things we saw yesterday then..., I opened an issue: [Unicast Discovery: When providing a comma separated list of addresses, trim them from whitespaces · Issue #1193 · elastic/elasticsearch · GitHub](https://github.com/elasticsearch/elasticsearch/issues/1193). On Tue, Aug 2, 2011 at 1:14 PM, Michel Conrad \<[michel.conrad@trendiction.com](mailto:michel.conrad@trendiction.com) > wrote: > Hi, > changing the configuration file solved the joining issue: > > When the hosts are comma separated and there is a whitespace after the > comma, the debug message prints correctly: > [DEBUG][discovery.zen.ping.unicast] [Jackson Arvad] using initial > hosts [192.168.5.1[9300], 192.168.5.2[9300], 192.168.5.3[9300], > 192.168.5.4[9300], 192.168.5.5[9300]] > > But only the first host is being used, the other four give an > java.nio.channels.UnresolvedAddressException on the netty layer. > > I think it would be helpful if the addresses would be trimmed before > being passed to netty or if it would be possible to give a warning in > order to avoid similar errors in the future. > > Regards, > Michel > > On Tue, Aug 2, 2011 at 10:52 AM, Michel Conrad > [michel.conrad@trendiction.com](mailto:michel.conrad@trendiction.com) wrote: > > > Hi, > > Thanks Shay for the extensive debugging yesterday on IRC. > > Everything seems much clearer now, but I think I found a situation > > where the cluster joining > > does not work as expected. > > > > I got the following situation during startup: > > > > minimum\_master\_nodes set to 3 > > master:true on 5 nodes, > > master:false on the other nodes. > > unicast discovery with hosts set to the 5 nodes that can become master. > > > > During the initial cluster everything works fine, a master is elected > > and the other nodes join the cluster. > > > > If I remove a non-master node from cluster, then try to join again the > > node does not join anymore. > > It only gets a ping response from the elected master and does not join > > the cluster. I suspect its because minimum\_master\_nodes is > > set to 3 and the unelected masters are somehow not responding to the > > ping. > > > > If I restart another node, the first node gets a ping response from > > the master (with master=true, [master=Cerberus...] and from the other > > node that tries to join the cluster (with master=false, master > > [null]). Still not joining any cluster. > > > > Only if I set minimum\_master\_nodes to 1 the node joins the cluster, > > but I thought that I wanted that the node > > can only join a cluster with 3 master nodes, to prevent split-brains. > > Or does it already prevent split-brains if I > > set minimum\_master\_nodes to 3 for the master:true nodes, and > > minimum\_master\_nodes to 1 for the master:false nodes? > > The only thing I suspect is that if I restart one of the 5 master:true > > nodes, that one also cannot join the cluster again. > > > > Best, > > Michel ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 6, 2017, 3:58am UTC](https://discuss.elastic.co/t/minimum-master-nodes-prevent-nodes-from-joining-the-cluster/5026/4 "2017-07-06T03:58:32Z")
Closed on July 6, 2017, 3:58am UTC