Managing the Job Tracker

Examples for using dsetool and dse client-tool commands to identify and manage Job Tracker nodes.

Several dsetool and dse client-tool commands are useful for managing Job Tracker nodes:

dsetool autojt datacenter
If you do not specify the datacenter name, the command elects Job Trackers for all datacenters. Automatically manage Job Tracker selection and remove manual selections. If the current manually selected tracker is up, the manually selected Job Tracker continues to be used.
dsetool jobtracker
Replaced by the dse client-tool hadoop job-tracker-address command.
dsetool setjt node IP
Moves the Job Tracker, or the Spark Master, and notifies the Task Tracker nodes of the change.
dsetool setrjt node IP
Moves the reserve Job Tracker and notifies the Task Tracker nodes of the change.
dsetool sparkmaster
For SparkMaster only. Returns the Job Tracker hostname and port to your location in the datacenter where you issued the command.
dsetool listjt
Lists all Job Tracker nodes grouped by their local datacenter.
dsetool ring
Lists the nodes and types of the nodes in the ring and the following Job Tracker status:
- (JT) the active Job Tracker
- (PT) an inactive primary tracker, when the primary tracker is down
- (RT) an inactive reserve tracker, when the reserve tracker is up while there is a primary tracker

These dsetool commands also work for Spark Master, except for dsetool jobtracker. The Spark Master equivalent command is dsetool sparkmaster.

For dsetool commands and options, see dsetool.

Listing Job Trackers example

To determine which nodes in your DataStax Enterprise cluster are Job Tracker nodes, run the following command:

Installer-Services and Package installations:
```
$ dsetool jobtracker
```
Installer-No Services and Tarball installations:
```
$ install_location/bin/dsetool jobtracker
```

Moving the Job Tracker node example

If your primary Job Tracker node fails, move the Job Tracker to another analytics node in the cluster. In-progress MapReduce jobs fail when you move the Job Tracker node or when the node goes down.

Procedure

Log in to a DataStax Enterprise analytics node.
Run the dsetool setjt command and specify the IP address of the new Job Tracker node in your DataStax Enterprise cluster. For example, to move the Job Tracker to node 110.82.155.4:
- Installer-Services and Package installations:
```
$ dsetool setjt 110.82.155.4
```
- Installer-No Services and Tarball installations:
```
$ install_location/bin/dsetool setjt 110.82.155.4
```
Allow 20 seconds for all of the analytics nodes to detect the change and restart their Task Tracker processes.
In a browser, connect to the new Job Tracker node and confirm that it is up and running. For example (change the IP to reflect your Job Tracker node IP):
```
http://110.82.155.4:50030
```
If you are running Hive or Pig MapReduce clients, restart them to pick up the new Job Tracker node information.