Hi all, I´m only testing the new HA feature. I´m not in a production system,
Well, let´s talk about the number of nodes and the ZKFC daemons. In this url: https://ccp.cloudera.com/display/CDH4DOC/HDFS+High+Availability+Initial+Deployment#HDFSHighAvailabilityInitialDeployment-DeployingAutomaticFailover you can read: If you have configured automatic failover using the ZooKeeper FailoverController (ZKFC), you must install and start thezkfc daemon on each of the machines that runs a NameNode. So, the number of ZKFC daemons are two, but reading this url: http://archive.cloudera.com/cdh4/cdh/4/hadoop/hadoop-yarn/hadoop-yarn-site/HDFSHighAvailabilityWithQJM.html#Deploying_ZooKeeper you can read this: In a typical deployment, ZooKeeper daemons are configured to run on three or five nodes I think that to ensure a good HA enviroment (of any kind) you need and odd number of nodes to avoid split-brain. The problem I see here is that If ZKFC monitors NameNodes in a CDH4 enviroment you only have 2 NN (active+standby). So I´m a bit confussed with this deployment... Any suggestion? Thanks in advance for all your answers Kind regards, ESGLinux 2013/1/14 Colin McCabe <[email protected]> > On Mon, Jan 14, 2013 at 11:49 AM, Colin McCabe <[email protected]> > wrote: > > Hi ESGLinux, > > > > In production, you need to run QJM on at least 3 nodes. You also need > > to run ZKFC on at least 3 nodes. You can run them on the same nodes > > if you like, though. > > Er, this should read "You also need to run ZooKeeper on at least 3 > nodes." ZKFC, which talks to ZooKeeper, runs on only two nodes-- the > active NN node and the standby NN node. > > Colin > > > > > Of course, none of this is "needed" to set up an example cluster. If > > you just want to try something out, you can run everything on the same > > node if you want. It depends on what you're trying to do. > > > > cheers, > > Colin > > > > > > On Fri, Dec 28, 2012 at 3:02 AM, ESGLinux <[email protected]> wrote: > >> Thank you for your answer Craig, > >> > >> I´m planning my cluster and for now I´m not sure how many machines I > need;-) > >> > >> If I have doubt i´ll what clouder say and If have a problem I have > where to > >> ask for explications :-) > >> > >> ESGLinux > >> > >> > >> > >> 2012/12/28 Craig Munro <[email protected]> > >>> > >>> OK, I have reliable storage on my datanodes so not an issue for me. If > >>> that's what Cloudera recommends then I'm sure it's fine. > >>> > >>> On Dec 28, 2012 10:38 AM, "ESGLinux" <[email protected]> wrote: > >>>> > >>>> Hi Craig, > >>>> > >>>> I´m a bit confused, I have read this from cloudera: > >>>> > https://ccp.cloudera.com/display/CDH4DOC/Hardware+Configuration+for+Quorum-based+Storage > >>>> > >>>> The JournalNode daemon is relatively lightweight, so these daemons can > >>>> reasonably be collocated on machines with other Hadoop daemons, for > example > >>>> NameNodes, the JobTracker, or the YARN ResourceManager. > >>>> Cloudera recommends that you deploy the JournalNode daemons on the > >>>> "master" host or hosts (NameNode, Standby NameNode, JobTracker, etc.) > so the > >>>> JournalNodes' local directories can use the reliable local storage on > those > >>>> machines. > >>>> There must be at least three JournalNode daemons, since edit log > >>>> modifications must be written to a majority of JournalNodes > >>>> > >>>> as you can read they recommend to put journalnode daemons with the > >>>> namenodes, but you say the opposite.??¿?¿?? > >>>> > >>>> > >>>> Thanks for your answer, > >>>> > >>>> ESGLinux, > >>>> > >>>> > >>>> > >>>> > >>>> 2012/12/28 Craig Munro <[email protected]> > >>>>> > >>>>> You need the following: > >>>>> > >>>>> - active namenode + zkfc > >>>>> - standby namenode + zkfc > >>>>> - pool of journal nodes (odd number, 3 or more) > >>>>> - pool of zookeeper nodes (odd number, 3 or more) > >>>>> > >>>>> As the journal nodes hold the namesystem transactions they should > not be > >>>>> co-located with the namenodes in case of failure. I distribute the > journal > >>>>> and zookeeper nodes across the hosts running datanodes or as Harsh > says you > >>>>> could co-locate them on dedicated hosts. > >>>>> > >>>>> ZKFC does not monitor the JobTracker. > >>>>> > >>>>> Regards, > >>>>> Craig > >>>>> > >>>>> On Dec 28, 2012 9:25 AM, "ESGLinux" <[email protected]> wrote: > >>>>>> > >>>>>> Hi, > >>>>>> > >>>>>> well, If I have understand you I can configure my NN HA cluster this > >>>>>> way: > >>>>>> > >>>>>> - Active NameNode + 1 ZKFC daemon + Journal Node > >>>>>> - Standby NameNode + 1 ZKFC daemon + Journal Node > >>>>>> - JobTracker node + 1 ZKFC daemon + Journal Node, > >>>>>> > >>>>>> Is this right? > >>>>>> > >>>>>> Thanks in advance, > >>>>>> > >>>>>> ESGLinux, > >>>>>> > >>>>>> 2012/12/27 Harsh J <[email protected]> > >>>>>>> > >>>>>>> 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 <[email protected]> > 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 > >>>>>> > >>>>>> > >>>> > >> >
