[zz]Unrecognized option: jvm

转载自：http://blog.csdn.net/viproc/article/details/7570866

情景描述：
        按照hadoop手册，搭建Single Node.
        启动hadoop时   #./start-all.sh
        报错：
        #######################################################
         localhost: Unrecognized option: -jvm
         localhost: Could not create the Java virtual machine.
        ######################################################    

环境：
      服务器：RHEL4.7_x86_64 内存：512M
      hadoop版本：hadoop-0.20.203.0rc1.tar.gz
      java版本：jdk-6u25-linux-x64.bin
        
解决：
   可以修改的地方有两个
      第一个(次要的)：/usr/local/hadoop/conf/hadoop-env.sh
       修改参数： export HADOOP_HEAPSIZE=256   #默认值为1000M，为Java虚拟机占用的内存的大小

  第二个(主要的)：
       查看/usr/local/hadoop/bin/hadoop源码：
       ####################################################################
       if [[ $EUID -eq 0 ]]; then
           HADOOP_OPTS="$HADOOP_OPTS -jvm server $HADOOP_DATANODE_OPTS"
       else
           HADOOP_OPTS="$HADOOP_OPTS -server $HADOOP_DATANODE_OPTS"
       fi
       ####################################################################
       如果以root身份启动，则hadoop启动java虚拟机时，会带上-jvm参数。
       不同的java版本，启动参数可能会不一致，由此导致以上问题。
      
       其他解释
       (详细见链接地址：
       http://mail-archives.apache.org/mod_mbox/hadoop-hdfs-user/201105.mbox
       /%3CBANLkTinm3q4EAo=GkeMjG67ZnXXRLRV+yw@mail.gmail.com%3E)：
       ####################################################################     

            > I think, that code is there for jsvc. If you run hadoop in secure mode, it             
            > executes this path. There is nothing wrong in -jvm option since it meant for             
            > jsvc.             
            >             
            > In case of secure mode, jsvc process runs as root and invokes the datanode             
            > process as hdfs user (or any other configured user).            
            > But it seems there is a bug in the code, if you run as root in non-secured             
            > mode this issue can trigger.             
            >
       ####################################################################       

       因此，
       新建一个hadoop用户，
       重新初始化操作：#./hadoop namenode -format
       再次启动hadoop: #./start-all.sh
       正常。
      
补充： 修改JAVA_HEAP_MAX的大小：
        # vi bin/hadoop
          JAVA_HEAP_MAX=-Xmx1000m
   
       输出结果：
##############################################################################################################
[hadoop@localhost bin]$ ./start-all.sh
starting namenode, logging to /usr/local/hadoop/bin/../logs/hadoop-hadoop-namenode-localhost.out
localhost: starting datanode, logging to /usr/local/hadoop/bin/../logs/hadoop-hadoop-datanode-localhost.out
localhost: starting secondarynamenode, logging to /usr/local/hadoop/bin/../logs/hadoop-hadoop-secondarynamenode-localhost.out
starting jobtracker, logging to /usr/local/hadoop/bin/../logs/hadoop-hadoop-jobtracker-localhost.out
localhost: starting tasktracker, logging to /usr/local/hadoop/bin/../logs/hadoop-hadoop-tasktracker-localhost.out
####################################################################################