1、启动journalnode时存在警告信息，sbin/hadoop-daemon.sh stop journalnode

starting journalnode, logging to /app/hadoop-2.2.0/logs/hadoop-root-journalnode-qasdba.out

Java HotSpot(TM) 64-Bit Server VM warning: You have loaded library /app/hadoop-2.2.0/lib/native/libhadoop.so which might have disabled stack guard. The VM will try to fix the stack guard now.

It's highly recommended that you fix the library with 'execstack -c ', or link it with '-z noexecstack'.

解决：增加环境变量

export HADOOP_HOME=/app/hadoop-2.2.0
export PATH=$HADOOP_HOME/bin:$PATH:...
export HADOOP_COMMON_LIB_NATIVE_DIR=$HADOOP_HOME/lib/native
export HADOOP_OPTS="-Djava.library.path=$HADOOP_HOME/lib"