Hi, I'm running Hadoop 0.19.1 on a cluster with 8 machines, 7 of which are
used as slaves and the other the master, each with 2 dual-core AMD CPUs and
generous amounts of RAM. I am running map-only jobs and have the slaves set
up to have 4 mappers each, for a total of 28 available mappers. When I
first start up my cluster, I am able to use all 28 mappers. However, after
a short bit of time (~12 hours), jobs that I submit start using fewer
mappers. I restarted my cluster last night, and currently only 19 mappers
are running tasks even though more tasks are pending, with at least 2 tasks
running per machine - so no machine has gone down. I have checked that the
unused cores are actually sitting idle. Any ideas for why this is
happening? Is there a way to restart Hadoop on the individual slaves?
Thanks! Mac
