ClusterState is kept in memory and Solr is notified of ClusterState updates by ZooKeeper when a change happens - Solr then grabs the latest ClusterState. If ZooKeeper goes down, Solr keeps using the in memory ClusterState it has and simply stops getting any new ClusterState updates until ZooKeeper comes back.
- Mark On May 6, 2013, at 2:59 AM, Furkan KAMACI <furkankam...@gmail.com> wrote: > Hi Mark; > > You said: "So it's pretty simple - when you lost the ability to talk to ZK, > everything keeps working based on the most recent clusterstate - except > that updates are blocked and you cannot add new nodes to the cluster." > Where nodes keeps cluster stat? When a query comes to a node that is at > another shard's replica, how query will return accurately? > > 2013/5/5 Jack Krupansky <j...@basetechnology.com> > >> Is soul retrieval possible when ZooKeeper is down? >> >> -- Jack Krupansky >> >> -----Original Message----- From: Mark Miller >> Sent: Sunday, May 05, 2013 2:19 PM >> To: solr-user@lucene.apache.org >> Subject: Re: disaster recovery scenarios for solr cloud and zookeeper >> >> >> When Solr loses it's connection to ZooKeeper, updates will start being >> rejected. Read requests will continue as normal. This is regardless of how >> long ZooKeeper is down. >> >> So it's pretty simple - when you lost the ability to talk to ZK, >> everything keeps working based on the most recent clusterstate - except >> that updates are blocked and you cannot add new nodes to the cluster. You >> are essentially in steady state. >> >> The ZK clients will continue trying to reconnect so that when ZK comes >> back updates while start being accepted again and new nodes may join the >> cluster. >> >> - Mark >> >> On May 3, 2013, at 3:21 PM, Dennis Haller <dhal...@talenttech.com> wrote: >> >> Hi, >>> >>> Solr 4.x is architected with a dependency on Zookeeper, and Zookeeper is >>> expected to have a very high (perfect?) availability. With 3 or 5 >>> zookeeper >>> nodes, it is possible to manage zookeeper maintenance and online >>> availability to be close to %100. But what is the worst case for Solr if >>> for some unanticipated reason all Zookeeper nodes go offline? >>> >>> Could someone comment on a couple of possible scenarios for which all ZK >>> nodes are offline. What would happen to Solr and what would be needed to >>> recover in each case? >>> 1) brief interruption, say <2 minutes, >>> 2) longer downtime, say 60 min >>> >>> Thanks >>> Dennis >>> >> >>
