Hi, There are two different things here: Automatic Failover and Quorum Journal Manager. The former, used via a ZooKeeper Failover Controller, is to manage failovers automatically (based on health checks of NNs). The latter, used via a set of Journal Nodes, is a medium of shared storage for namesystem transactions that helps enable HA.
In a typical deployment, you want 3 or more (odd) JournalNodes for reliable HA, preferably on nodes of their own if possible (like you would for typical ZooKeepers, and you may co-locate with those as well) and one ZKFC for each NameNode (connected to the same ZK quorum). On Thu, Dec 27, 2012 at 5:33 PM, ESGLinux <esggru...@gmail.com> wrote: > Hi all, > > I have a doubt about how to deploy the Zookeeper in a NN HA cluster, > > As far as I know, I need at least three nodes to run three ZooKeeper > FailOver Controller (ZKFC). I plan to put these 3 daemons this way: > > - Active NameNode + 1 ZKFC daemon > - Standby NameNode + 1 ZKFC daemon > - JobTracker node + 1 ZKFC daemon, (is this right?) > > so the quorum is formed with these three nodes. The nodes that runs a > namenode are right because the ZKFC monitors it, but what does the third > daemon? > > as I read from this url: > https://ccp.cloudera.com/display/CDH4DOC/Software+Configuration+for+Quorum-based+Storage#SoftwareConfigurationforQuorum-basedStorage-AutomaticFailoverConfiguration > > this daemons are only related with NameNodes, (Health monitoring - the ZKFC > pings its local NameNode on a periodic basis with a health-check command.) > so what does the third ZKFC? I used the jobtracker node but I could use > another node without any daemon on it... > > Thanks in advance, > > ESGLInux, > > > -- Harsh J
