按照alluxio官网的单机或者集群安装教程，在进行 bin/alluxio format时出现错误： question1：
[localhost] Exception in thread "main" java.lang.UnsupportedClassVersionError: alluxio/cli/Format : Unsupported major.minor version 51.0 [localhost] at java.lang.ClassLoader.defineClass1(Native Method) [localhost] at java.lang.ClassLoader.defineClass(ClassLoader.java:634) [localhost] at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) [localhost] at java.net.URLClassLoader.defineClass(URLClassLoader.java:277) [localhost] at java.net.URLClassLoader.access$000(URLClassLoader.java:73) [localhost] at java.net.URLClassLoader$1.run(URLClassLoader.java:212) [localhost] at java.security.AccessController.doPrivileged(Native Method) [localhost] at java.net.URLClassLoader.findClass(URLClassLoader.java:205) [localhost] at java.lang.ClassLoader.loadClass(ClassLoader.java:321) [localhost] at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294) [localhost] at java.lang.ClassLoader.loadClass(ClassLoader.java:266)在stackoverflow查看后，说是编译程序在高版本的java,但是运行在了较低版本，所以出现了版本不支持情况。然后查了所使用的测试机，java -version显示已是java1.8. 最后决定使用maven自行编译，在pom.xml中修改<hadoop.version>版本后，在jdk7的环境中执行mvn clean package -DskipTests 。问题解决。【1.8环境编译成功但是无法启动，a bug???】
question2：
[node2] Formatting Alluxio Worker @ node2 [node2] Exception in thread "main" java.lang.NoClassDefFoundError: alluxio/cli/Format [node2] Caused by: java.lang.ClassNotFoundException: alluxio.cli.Format [node2] at java.net.URLClassLoader$1.run(URLClassLoader.java:217) [node2] at java.security.AccessController.doPrivileged(Native Method) [node2] at java.net.URLClassLoader.findClass(URLClassLoader.java:205) [node2] at java.lang.ClassLoader.loadClass(ClassLoader.java:321) [node2] at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294) [node2] at java.lang.ClassLoader.loadClass(ClassLoader.java:266) [node2] Could not find the main class: alluxio.cli.Format. Program will exit. [node2] Connection to node2 closed.bin/alluxio-start.sh local之后发现是以下问题
Could not create ServerSocket on address /0.0.0.0:19998.在alluxio-1.4.0/conf/alluxio-site.properties中增加配置项
export alluxio.master.port=18998 export alluxio.master.web.port=18999然后重新执行bin/alluxio-start.sh local即可发现系统启动成功
