hadoop启动namenode失败异常，求解决方法，小弟不胜感激！！！

问题描述：前面集群都是正常，今天向hadoop-env.sh中添加hbase环境变量后，启动namenode就出现该错误！

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2015-03-11 17:05:59,334 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: registered UNIX signal handlers for [TERM, HUP, INT]
2015-03-11 17:05:59,339 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: createNameNode []
2015-03-11 17:05:59,831 INFO org.apache.hadoop.metrics2.impl.MetricsConfig: loaded properties from hadoop-metrics2.properties
2015-03-11 17:05:59,925 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Scheduled snapshot period at 10 second(s).
2015-03-11 17:05:59,926 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: NameNode metrics system started
2015-03-11 17:05:59,928 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: fs.defaultFS is hdfs://10.1.20.241:8020
2015-03-11 17:05:59,929 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: Clients are to use 10.1.20.241:8020 to access this namenode/service.
2015-03-11 17:06:00,523 INFO org.apache.hadoop.hdfs.DFSUtil: Starting web server as: ${dfs.web.authentication.kerberos.principal}
2015-03-11 17:06:00,523 INFO org.apache.hadoop.hdfs.DFSUtil: Starting Web-server for hdfs at: http://namenode:50070
2015-03-11 17:06:00,760 INFO org.apache.hadoop.http.HttpRequestLog: Http request log for http.requests.namenode is not defined
2015-03-11 17:06:00,820 INFO org.apache.hadoop.http.HttpServer2: Added global filter 'safety' (class=org.apache.hadoop.http.HttpServer2$QuotingInputFilter)
2015-03-11 17:06:00,831 INFO org.apache.hadoop.http.HttpServer2: Added filter static_user_filter (class=org.apache.hadoop.http.lib.StaticUserWebFilter$StaticUserFilter) to context hdfs
2015-03-11 17:06:00,831 INFO org.apache.hadoop.http.HttpServer2: Added filter static_user_filter (class=org.apache.hadoop.http.lib.StaticUserWebFilter$StaticUserFilter) to context logs
2015-03-11 17:06:00,831 INFO org.apache.hadoop.http.HttpServer2: Added filter static_user_filter (class=org.apache.hadoop.http.lib.StaticUserWebFilter$StaticUserFilter) to context static
2015-03-11 17:06:00,913 INFO org.apache.hadoop.http.HttpServer2: Added filter 'org.apache.hadoop.hdfs.web.AuthFilter' (class=org.apache.hadoop.hdfs.web.AuthFilter)
2015-03-11 17:06:00,916 INFO org.apache.hadoop.http.HttpServer2: addJerseyResourcePackage: packageName=org.apache.hadoop.hdfs.server.namenode.web.resources;org.apache.hadoop.hdfs.web.resources, pathSpec=/webhdfs/v1/*
2015-03-11 17:06:00,952 INFO org.apache.hadoop.http.HttpServer2: Jetty bound to port 50070
2015-03-11 17:06:02,034 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Stopping NameNode metrics system...
2015-03-11 17:06:02,035 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: NameNode metrics system stopped.
2015-03-11 17:06:02,035 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: NameNode metrics system shutdown complete.
2015-03-11 17:06:02,036 FATAL org.apache.hadoop.hdfs.server.namenode.NameNode: Failed to start namenode.
java.io.IOException: Problem in starting http server. Server handlers failed

        at org.apache.hadoop.http.HttpServer2.start(HttpServer2.java:839)

        at org.apache.hadoop.hdfs.server.namenode.NameNodeHttpServer.start(NameNodeHttpServer.java:142)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.startHttpServer(NameNode.java:695)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:585)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:754)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:738)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1427)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1493)
2015-03-11 17:06:02,042 INFO org.apache.hadoop.util.ExitUtil: Exiting with status 1
2015-03-11 17:06:02,045 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: SHUTDOWN_MSG: