Knowledge is Power
ZooKeeper Overview ZooKeeper allows distributed processes to coordinate with each other through a shared hierarchical name space of data registers (we call these registers znodes), much like a file system. Unlike normal file systems ZooKeeper provides its clients with high...
Are you seeing this ? org.apache.hadoop.hdfs.server.datanode.DataNode: java.io.IOException: Incompatible namespaceIDs in hadoop/dfs/data: namenode namespaceID = X; datanode namespaceID = Y The fix (in the order) Delete VERSION files in the dfs directory $ find /hadoop/dfs -name VERSION -exec rm -rf “{}”...
Is it 50030 or 50300 for that JobTracker UI? I can never remember! Hadoop’s daemons expose a handful of ports over TCP. Some of these ports are used by Hadoop’s daemons to communicate amongst themselves (to schedule jobs, replicate blocks,...
Source: http://bradhedlund.com/2011/09/10/understanding-hadoop-clusters-and-the-network/ This article is Part 1 in series that will take a closer look at the architecture and methods of a Hadoop cluster, and how it relates to the network and server infrastructure. The content presented here is largely...
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