Job Trackers for DSE Hadoop and external Hadoop 

Job Trackers are used for analytics nodes that analyze data using Hadoop, including DSE Hadoop and external Hadoop systems.

Job Trackers are used for analytics nodes that analyze data using Hadoop, including DSE Hadoop and external Hadoop systems.

For each MapReduce job that is submitted to the Job Tracker, DataStax Enterprise schedules a series of tasks on the analytics nodes. One Task Tracker service per node handles the map and reduce tasks that are scheduled for that node. Within a datacenter, the Job Tracker monitors the execution and status of distributed tasks that comprise a MapReduce job.

Note: If the Job Tracker is not manually set after you enable the automatic Job Tracker setting using the dsetool utility, the Job Tracker is reassigned when the reserve tracker is set.

Using multiple Job Tracker services 

You can use multiple Job Tracker nodes in a cluster, one per datacenter. In deployments that have multiple datacenters far away from each other, using multiple Job Trackers and multiple file systems can improve performance by taking advantage of data locality on each cluster.