MapReduce (MRv1) JobTracker High Availability

Follow the instructions in this section to configure high availability (HA) for JobTracker.

Configuring MapReduce (MRv1) JobTracker High Availability Using Cloudera Manager

Minimum Required Role: Cluster Administrator (also provided by Full Administrator)

You can use Cloudera Manager to configure CDH 4.3 or higher for JobTracker high availability (HA). Although it is possible to configure JobTracker HA with CDH 4.2, it is not recommended. Rolling restart, decommissioning of TaskTrackers, and rolling upgrade of MapReduce from CDH 4.2 to CDH 4.3 are not supported when JobTracker HA is enabled.

Cloudera Manager supports automatic failover of the JobTracker. It does not provide a mechanism to manually force a failover through the Cloudera Manager user interface.

Enabling JobTracker High Availability

The Enable High Availability workflow leads you through adding a second (standby) JobTracker:
  1. Go to the MapReduce service.
  2. Select Actions > Enable High Availability. A screen showing the hosts that are eligible to run a standby JobTracker displays. The host where the current JobTracker is running is not available as a choice.
  3. Select the host where you want the Standby JobTracker to be installed, and click Continue.
  4. Enter a directory location on the local filesystem for each JobTracker host. These directories will be used to store job configuration data.
    • You may enter more than one directory, though it is not required. The paths do not need to be the same on both JobTracker hosts.
    • If the directories you specify do not exist, they will be created with the appropriate permissions. If they already exist, they must be empty and have the appropriate permissions.
    • If the directories are not empty, Cloudera Manager will not delete the contents.
  5. Optionally use the checkbox under Advanced Options to force initialize the ZooKeeper znode for auto-failover.
  6. Click Continue. Cloudera Manager runs a set of commands that stop the MapReduce service, add a standby JobTracker and Failover controller, initialize the JobTracker high availability state in ZooKeeper, create the job status directory, restart MapReduce, and redeploy the relevant client configurations.

Disabling JobTracker High Availability

  1. Go to the MapReduce service.
  2. Select Actions > Disable High Availability. A screen showing the hosts running the JobTrackers displays.
  3. Select which JobTracker (host) you want to remain as the single JobTracker, and click Continue. Cloudera Manager runs a set of commands that stop the MapReduce service, remove the standby JobTracker and the Failover Controller, restart the MapReduce service, and redeploy client configurations.