No, there is no majority decision here. Perhaps you don't join the right node. You should have both in seed-nodes and in same order. It should be clear from info level logging what is going on. tis 4 apr. 2017 kl. 12:26 skrev Unmesh Joshi <unmeshjo...@gmail.com>:
> Curiously, my observation is that if instead of two, I have four node > cluster and crash/restart a node with same host/port, I do not get this > warning. I get this only on two node cluster, which made me think that > there is majority needed to mark the new incarnation as 'seen' and then > down the previous incarnation. > > > On Tuesday, 4 April 2017 15:17:45 UTC+5:30, Patrik Nordwall wrote: > > One way of downing is to join again with same host:port. That will trigger > downing of previous incarnation and when removal is done the new > incarnation can join by trying to join again. The seed-nodes joining will > retry the joining automatically. > > However, sooner or later you will need a real downing strategy. > > /Patrik > > tis 4 apr. 2017 kl. 10:31 skrev 'Michal Borowiecki' via Akka User List < > akka...@googlegroups.com>: > > Indeed. This is the relevant bit of docs I believe ( > http://doc.akka.io/docs/akka/2.4.17/common/cluster.html#Membership): > > The node identifier internally also contains a UID that uniquely > identifies this actor system instance at that hostname:port. Akka uses > the UID to be able to reliably trigger remote death watch. This means that > the same actor system can never join a cluster again once it's been removed > from that cluster. To re-join an actor system with the same hostname:port to > a cluster you have to stop the actor system and start a new one with the > same hostname:portwhich will then receive a different UID. > > After re-starting the node it will get a new UID and will be considered a > new member. > > The unreachable member (the previous incarnation of your node) needs to be > downed first for new members to be admitted by the leader. > > Cheers, > > Michal > > > On 04/04/17 08:58, Viktor Klang wrote: > > No, it needs to be Downed. > > > On Tue, Apr 4, 2017 at 9:50 AM, Unmesh Joshi <unmes...@gmail.com> wrote: > > Hi, > > If I restart the crashed node on same host and port, it should be > reachable now and consensus should be reached isnt it? > > Thanks, > Unmesh > > On Tuesday, 4 April 2017 13:09:22 UTC+5:30, Michal Borowiecki wrote: > > Hi Unmesh, > > AFAIK, the crashed node has to be downed (whether manually or > automatically) for the cluster to reach convergence. > > Only once there are no unreachable nodes observed by any member can the > leader resume it's duties and allow the new member (your re-started > instance) to join. > > For testing & dev, you can use auto-downing. For production you need to > choose a more resilient approach I'm afraid, as out of the box auto-downing > doesn't provide a way to address the split-brain-problem which most likely > would bite you in a real life environment sooner or later. > > Cheers, > > Michal > > On 04/04/17 08:31, Unmesh Joshi wrote: > > Is it possibly because in a two node cluster, there can never be majority > ( > 50%) nodes agreeing on membership to mark a node as 'seen'? > > On Tuesday, 4 April 2017 12:46:17 UTC+5:30, Unmesh Joshi wrote: > > Hi, > > I have a two node cluster in a cluster. If I crash one of the nodes > (*10.131.22.26:3552 > <http://10.131.22.26:3552>), *and bring it up again, I start getting > following messages from other nodes. Now that the node is reachable and > there are only two nodes in the cluster, why should it give following > message with seen=false for 1*0.131.22.26:3552 > <http://0.131.22.26:3552>? * > For members to be seen, is there any other configuration that needs to be > tuned? > > > [INFO] [04/04/2017 12:38:49.623] > [csw-cluster-akka.actor.default-dispatcher-14] > [akka.cluster.Cluster(akka://csw-cluster)] Cluster Node [akka.tcp:// > csw-cluster@10.131.22.26:41574] - Leader can currently not perform its > duties, reachability status: [akka.tcp://csw-cluster@10.131.22.26:41574 > -> akka.tcp://csw-cluster@10.131.22.26:3552: Unreachable [Unreachable] > (1)], member status: [akka.tcp://csw-cluster@10.131.22.26:3552 Up > seen=false, akka.tcp://csw-cluster@10.131.22.26:41574 Up seen=true] > [INFO] [04/04/2017 12:39:49.634] > [csw-cluster-akka.actor.default-dispatcher-2] > [akka.cluster.Cluster(akka://csw-cluster)] Cluster Node [akka.tcp:// > csw-cluster@10.131.22.26:41574] - Leader can currently not perform its > duties, reachability status: [akka.tcp://csw-cluster@10.131.22.26:41574 > -> akka.tcp://csw-cluster@10.131.22.26:3552: Unreachable [Unreachable] > (1)], member status:* [akka.tcp://csw-cluster@10.131.22.26:3552 > <http://csw-cluster@10.131.22.26:3552> Up seen=false*, akka.tcp:// > csw-cluster@10.131.22.26:41574 Up seen=true] > [INFO] [04/04/2017 12:40:49.632] > [csw-cluster-akka.actor.default-dispatcher-17] > [akka.cluster.Cluster(akka://csw-cluster)] Cluster Node [akka.tcp:// > csw-cluster@10.131.22.26:41574] - Leader can currently not perform its > duties, reachability status: [akka.t > > > > Thanks, > Unmesh > > -- > >>>>>>>>>> Read the docs: http://akka.io/docs/ > >>>>>>>>>> Check the FAQ: > http://doc.akka.io/docs/akka/current/additional/faq.html > >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user > --- > You received this message because you are subscribed to the Google Groups > "Akka User List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to akka-user+...@googlegroups.com. > To post to this group, send email to akka...@googlegroups.com. > Visit this group at https://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/d/optout. > > > -- > <http://www.openbet.com/> Michal Borowiecki > Senior Software Engineer L4 > T: +44 208 742 1600 > > > +44 203 249 8448 > > > > E: michal.b...@openbet.com > W: www.openbet.com > OpenBet Ltd > > Chiswick Park Building 9 > > 566 Chiswick High Rd > > London > > W4 5XT > > UK > <https://www.openbet.com/email_promo> > This message is confidential and intended only for the addressee. 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GB927523612 > > -- > >>>>>>>>>> Read the docs: http://akka.io/docs/ > >>>>>>>>>> Check the FAQ: > http://doc.akka.io/docs/akka/current/additional/faq.html > >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user > --- > You received this message because you are subscribed to the Google Groups > "Akka User List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to akka-user+...@googlegroups.com. > To post to this group, send email to akka...@googlegroups.com. > Visit this group at https://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/d/optout. > > > > > -- > > Cheers, > √ > > -- > >>>>>>>>>> Read the docs: http://akka.io/docs/ > >>>>>>>>>> Check the FAQ: > http://doc.akka.io/docs/akka/current/additional/faq.html > >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user > --- > You received this message because you are subscribed to the Google Groups > "Akka User List" group. > > To unsubscribe from this group and stop receiving emails from it, send an > email to akka-user+...@googlegroups.com. > To post to this group, send email to akka...@googlegroups.com. > Visit this group at https://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/d/optout. > > -- > <http://www.openbet.com/> Michal Borowiecki > Senior Software Engineer L4 > T: +44 208 742 1600 > > > +44 203 249 8448 > > > > E: michal.b...@openbet.com > W: www.openbet.com > OpenBet Ltd > > Chiswick Park Building 9 > > 566 Chiswick High Rd > > London > > W4 5XT > > UK > <https://www.openbet.com/email_promo> > This message is confidential and intended only for the addressee. 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