On Thu, Apr 30, 2015 at 2:04 PM, Chris Nauroth <[email protected]> wrote: > Hello Richard, > > The "hdfs zkfc" command used as part of HDFS HA is a Hadoop-specific > solution that implements an additional layer of logic on top of a > ZooKeeper distributed lock. The additional logic relates to transitioning > NameNode processes between active and standby state, and fencing of an old > active NameNode in case it still believes itself to be active due to a > network partition or other malfunction. The code for this resides in the > Hadoop project, not ZooKeeper. It is considered a private implementation > detail of Hadoop, not a stable public API, so I recommend against writing > code that relies on those classes. It might still be interesting to read > the code as inspiration for your own implementation though. If you're > interested, take a look at the following spots in the Hadoop source tree: > > hadoop-hdfs-project/hadoop-hdfs/src/main/java//org/apache/hadoop/hdfs/tools > /DFSZKFailoverController.java > hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server > /namenode/ha/ > hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ha/
Thanks for that info ... -- Regards, Richard Sharpe (何以解憂？唯有杜康。--曹操)
