On Thu, Aug 25, 2011 at 1:34 PM, Sesha Kumar sesha...@gmail.com wrote:
Hi all,
I am trying to get a good understanding of how Hadoop works, for my
undergraduate project. I have the following questions/doubts :
1. Why does namenode store the blockmap (block to datanode mapping) in the
main
My answers inline.
1. Why does namenode store the blockmap (block to datanode mapping) in the
main memory for all the files, even those that are not used?
The block to datanode mapping is needed for two reasons: when a client wants
to read a file, the namenode has to tell the client the
