Amar Kamat wrote:
Fabrizio detto Mario wrote:
Hello Hadoop community,
I read about Hadoop framework (
http://hadoop.apache.org/core/docs/r0.16.3/mapred_tutorial.html) this
phrase:
"The Map-Reduce framework consists of a single master JobTracker and one
slave TaskTracker per cluster-node..."
Is The Job Tracker (Master Node) unique and static for my cluster? Is
The
Job Tracker the same for each map/reduce run?
The job-tracker process controls certain task-trackers processes.
These task-trackers can be on same machine or different machines. One
task-tracker is controlled by a single job-tracker. You could have
multiple map-reduce clusters (each with different job-trackers) on a
same physical cluster. So here are the answers
1) The job-tracker is unique for a map-reduce cluster (logical)
consisting of a set of trackers. There can be multiple such
job-trackers each controlling different set of trackers, possibly in
the same physical cluster.
2) The job-tracker is same for all jobs that run on the same set of
trackers.
It is possible to have multiple task-trackers running simultaneously
on a same machine (differentiated by ports) and hence each tracker can
be under different job-trackers and hence one machine
"and hence each tracker can be under different job-trackers .."
should be
"and hence each node can be under different job-trackers .."
Amar
can be under multiple logical clusters.
Amar
If the response is positive, hadoop is different from map/reduce Google
implementation. In Google Implementation the Master node is "one
copies of
program" (See MapReduce: Simplified Data Processing on Large Clusters).
Thanks.
