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Namenode and Datanode file structure





Namenode and DataNode file structure:

 
Namenode:
Namenode contains Version,edits,fsimage and fstime.
VersionVersion is a unique namespace id which is common for the cluster.Whenever a new datanode is added ,namenode gives this id to the new datanodes for them to become part of cluster.
fsimage: Its a snapshot of file system.While staring a cluster ,it keeps a snapshot of file system in fsimage.
edits: Once after starting the cluster,the changes made to the file system are stored in fsimage but instead they are stored in edits log file.
fstime: It specifies the time at which last checkpoint was taken.

Datanode:
It contains the version directory which contains all namespaceid of the NN.Also it contains block reports


- See more at: http://labstrikes.blogspot.in/2012/08/adsense-middle-blog-post.html#sthash.gQgSkqx8.dpuf
 
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