NameNode is a very important server in Hadoop Distributed File System. It is the master node that keeps track of the metadata , references, sequence, permissions etc of the actual blocks of data. DataNodes send signal to the NameNode in every few seconds, so that NameNode can detect that the datanode is working properly. If NameNode don’t get signal from any DataNode then the DataNode is considered as dead. Namenode will decide which part of the data will be stored in which datanode. It takes care of replicating data file into blocks and distributing it across the cluster. The Namenode keeps an image of all this information in a local file or preferably on NFS mount. It also maintains a log, called the ‘edit log’, where all the changes are recorded. If NameNode goes down The HDFS goes down.
Managing a business data is not an easy thing, it is very complex process to handle the corporate information both Hadoop and cognos doing this in a easy manner with help of business software suite, thanks for sharing this useful post….
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A table is the basic unit of data storage in an oracle database. The table of a database hold all of the user accesible data. Table data is stored in rows and columns. But what is all about the clusters and how to handle it using oracle database system? Expecting a right answer from you. By the way you are maintaining a great blog. Thanks for sharing this in here.
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