错误：ssh：could not resolve ....

错误描述：

Java: ssh: Could not resolve hostname Java: Name or service not known
    library: ssh: Could not resolve hostname library: Name or service not known
    warning:: ssh: Could not resolve hostname warning:: Name or service not known
    which: ssh: Could not resolve hostname which: Name or service not known
    have: ssh: Could not resolve hostname have: Name or service not known
    might: ssh: Could not resolve hostname might: Name or service not known
    You: ssh: Could not resolve hostname You: Name or service not known
    loaded: ssh: Could not resolve hostname loaded: Name or service not known
    Server: ssh: Could not resolve hostname Server: Name or service not known
    HotSpot(TM): ssh: Could not resolve hostname HotSpot(TM): Name or service not known
    have: ssh: Could not resolve hostname have: Name or service not known
    64-Bit: ssh: Could not resolve hostname 64-Bit: Name or service not known
    VM: ssh: Could not resolve hostname VM: Name or service not known
    disabled: ssh: Could not resolve hostname disabled: Name or service not known
    VM: ssh: Could not resolve hostname VM: Name or service not known
    stack: ssh: Could not resolve hostname stack: Name or service not known
    The: ssh: Could not resolve hostname The: Name or service not known
    fix: ssh: Could not resolve hostname fix: Name or service not known
    try: ssh: Could not resolve hostname try: Name or service not known
    guard.: ssh: Could not resolve hostname guard.: Name or service not known
    to: ssh: Could not resolve hostname to: Name or service not known

解决： 在/etc/profile 中添加如下两条内容：

export HADOOP_COMMON_LIB_NATIVE_DIR=$HADOOP_INSTALL/lib/native
export HADOOP_OPTS="-Djava.library.path=$HADOOP_INSTALL/lib"

这里$HADOOP_INSTALL 指的是hadoop 的安装路径

source /etc/profile 刷新配置
重新启动HDFS，问题消失