If I remember correctly, version 1.4 can turn nodes that cant connect to the cluster to read only mode.
On Thursday, December 11, 2014 4:44:28 PM UTC, David Artus wrote: > > > My understanding is that recovery from Split Brain situations is > troublesome and we are encourages to ensure that a cluster is only active > if there is a quorum of candidate masters , we do that by setting > *discovery.zen.minimum_master_nodes* to ((cm/2) + 1), that is a true > majority of candidate masters. > > I also see that many folks want to enable resilience in the event of > disaster by running a cluster across two data centres. Lose one data center > and we just keep running in the other - we still have half our servers, so > with correct over-provisioning we can cope with the workload. No need to > rebuild the cluster and restore from backup. We have what may be called > Live/Live Disaster Recovery (DR) > > I see two issues with this approach to DR. If we lose half our candidate > master nodes, by definition we cannot achieve a quorum, we won't have a > true majority. > > A slightly more subtle problem is that we probabaly also set > *gateway.recover_after_nodes* to a high value (say 8 of 10) so that in > normal running with a few missing nodes we don't inadvertantly get into > shard shuffling. Once again with a loss of half our estate we will not > have enough nodes to satisfy that setting. > > My conclusion is that while Live/Live operation across two Data Centers is > possible the transition to a reduced state requires reconfiguration, the > system will not "just keep running" unless we open ourselves to Split Brain > and replica shuffling. > > Comments please? > > -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/elasticsearch/6dcfdeed-370f-426a-a5b1-f72767838d7f%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
