HDFS에 연결을 하지 못하는 문제점을 발견.
아래와 같은 에러가 난다면 호스트네임(hostname) 문제일 가능성이 있다.
/etc/hosts 를 확인 하기 바란다.

2013-10-24 21:56:51,681 (agent-shutdown-hook) [WARN - org.apache.flume.sink.hdfs.HDFSEventSink.stop(HDFSEventSink.java:442)] Exception while closing /logs/FlumeData. Exception follows.
java.net.ConnectException: Call From dev.yongbok.net/127.0.0.1 to localhost:9000 failed on connection exception: java.net.ConnectException: 연결이 거부됨; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
        at org.apache.hadoop.net.NetUtils.wrapWithMessage(NetUtils.java:783)
        at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:730)
        at org.apache.hadoop.ipc.Client.call(Client.java:1351)
        at org.apache.hadoop.ipc.Client.call(Client.java:1300)
        at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:206)
        at com.sun.proxy.$Proxy11.getFileInfo(Unknown Source)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:186)
        at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:102)
        at com.sun.proxy.$Proxy11.getFileInfo(Unknown Source)
        at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getFileInfo(ClientNamenodeProtocolTranslatorPB.java:651)
        at org.apache.hadoop.hdfs.DFSClient.getFileInfo(DFSClient.java:1679)
        at org.apache.hadoop.hdfs.DistributedFileSystem$17.doCall(DistributedFileSystem.java:1106)
        at org.apache.hadoop.hdfs.DistributedFileSystem$17.doCall(DistributedFileSystem.java:1102)
        at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
        at org.apache.hadoop.hdfs.DistributedFileSystem.getFileStatus(DistributedFileSystem.java:1102)
        at org.apache.hadoop.fs.FileSystem.exists(FileSystem.java:1397)
        at org.apache.flume.sink.hdfs.BucketWriter$7.call(BucketWriter.java:486)
        at org.apache.flume.sink.hdfs.BucketWriter$8$1.run(BucketWriter.java:536)
        at org.apache.flume.sink.hdfs.BucketWriter.runPrivileged(BucketWriter.java:160)
        at org.apache.flume.sink.hdfs.BucketWriter.access$1000(BucketWriter.java:56)
        at org.apache.flume.sink.hdfs.BucketWriter$8.call(BucketWriter.java:533)
        at java.util.concurrent.FutureTask.run(FutureTask.java:262)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:724)
Caused by: java.net.ConnectException: 연결이 거부됨
        at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
        at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:735)
        at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206)
        at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:529)
        at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:493)
        at org.apache.hadoop.ipc.Client$Connection.setupConnection(Client.java:547)
        at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:642)
        at org.apache.hadoop.ipc.Client$Connection.access$2600(Client.java:314)
        at org.apache.hadoop.ipc.Client.getConnection(Client.java:1399)
        at org.apache.hadoop.ipc.Client.call(Client.java:1318)
        ... 26 more