tried to run hadoop start-dfs.sh several times, which always throw out an exception
localhost: nice: cannot set niceness: Permission denied
checking jps, the start-dfs.sh only brought up nameNode and resourceManager.
Tried several approaches on set niceness with no avail. somehow actually calling the daemon to start the datanode directly works. (event the permission denied still exist.)
lwpro2@DESKTOP-G92MK3N:~/hadoop/hadoop-2.9.1$ sbin/hadoop-daemon.sh start datanode
starting datanode, logging to /home/lwpro2/hadoop/hadoop-2.9.1/logs/hadoop-lwpro2-datanode-DESKTOP-.out
nice: cannot set niceness: Permission denied