Hadoop study notes - balancer

# start-balancer.sh
starting balancer, logging to /usr/local/hadoop_20_1/bin/../logs/hadoop-loginuserid-balancer-hostname.out
#

The -threshold argument specifies the threshold percentage that defines what it means
for the cluster to be balanced. The flag is optional, in which case the threshold is 10%.
At any one time, only one balancer may be running on the cluster.