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java.lang.Objectorg.apache.hadoop.hdfs.server.namenode.SecondaryNameNode
@Deprecated @InterfaceAudience.Private public class SecondaryNameNode
The Secondary NameNode is a helper to the primary NameNode. The Secondary is responsible for supporting periodic checkpoints of the HDFS metadata. The current design allows only one Secondary NameNode per HDFs cluster. The Secondary NameNode is a daemon that periodically wakes up (determined by the schedule specified in the configuration), triggers a periodic checkpoint and then goes back to sleep. The Secondary NameNode uses the ClientProtocol to talk to the primary NameNode.
Field Summary | |
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static org.apache.commons.logging.Log |
LOG
Deprecated. |
Constructor Summary | |
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SecondaryNameNode(org.apache.hadoop.conf.Configuration conf)
Deprecated. Create a connection to the primary namenode. |
Method Summary | |
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static void |
main(String[] argv)
Deprecated. main() has some simple utility methods. |
void |
run()
Deprecated. |
void |
shutdown()
Deprecated. Shut down this instance of the datanode. |
String |
toString()
Deprecated. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Field Detail |
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public static final org.apache.commons.logging.Log LOG
Constructor Detail |
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public SecondaryNameNode(org.apache.hadoop.conf.Configuration conf) throws IOException
IOException
Method Detail |
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public String toString()
toString
in class Object
public void shutdown()
public void run()
run
in interface Runnable
public static void main(String[] argv) throws Exception
argv
- Command line parameters.
Exception
- if the filesystem does not exist.
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