Hadoop ZKFC Start

Start the NameNode service as well as its ZKFC daemon.

In HA mode, to ensure that the leadership is assigned to the desired active NameNode, the ZKFC daemons on the standy NameNodes wait for the one on the active NameNode to start first.

module.exports = header: 'HDFS ZKFC Start', handler: ({options}) ->

Wait

Wait for Kerberos, ZooKeeper and HDFS to be started.

  # @call once: true, 'masson/core/krb5_client/wait'
  # @call once: true, 'ryba/zookeeper/server/wait'
  # @call once: true, 'ryba/hadoop/hdfs_jn/wait'
  @call once: true, 'ryba/hadoop/hdfs_nn/wait', options.wait_hdfs_nn, conf_dir: options.nn_conf_dir

Wait Active NN

  @wait.execute
    header: 'Wait Active NN'
    if: options.active_nn_host isnt options.fqdn
    cmd: mkcmd.hdfs options.hdfs_krb5_user, "hdfs --config #{options.nn_conf_dir} haadmin -getServiceState #{options.active_shortname}"
    code_skipped: 255

Start

Start the ZKFC daemon. Important, ZKFC should start first on the active NameNode. You can also start the server manually with the following two commands:

service hadoop-hdfs-zkfc start
su -l hdfs -c "/usr/hdp/current/hadoop-client/sbin/hadoop-daemon.sh --config /etc/hadoop/conf --script hdfs start zkfc"

  @service.start
    header: 'Daemon'
    name: 'hadoop-hdfs-zkfc'

Wait Failover

Ensure a given NameNode is always active and force the failover otherwise.

In order to work properly, the ZKFC daemon must be running and the command must be executed on the same server as ZKFC.

  # Note, probably we shall wait for the other NameNode to be started and running
  # before attempting to activate it.
  @system.execute
    header: 'Failover'
    cmd: mkcmd.hdfs options.hdfs_krb5_user, """
    if hdfs --config #{options.nn_conf_dir} haadmin -getServiceState #{options.active_shortname} | grep standby;
    then hdfs --config #{options.nn_conf_dir} haadmin -ns #{options.dfs_nameservices} -failover #{options.standby_shortname} #{options.active_shortname};
    else exit 2; fi
    """
    code_skipped: 2

Dependencies

mkcmd = require '../../lib/mkcmd'