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Posted to hdfs-dev@hadoop.apache.org by "Vinayakumar B (JIRA)" <ji...@apache.org> on 2016/04/02 15:29:25 UTC
[jira] [Resolved] (HDFS-10252) Is DataNode aware of the name of the
file that it is going to store?
[ https://issues.apache.org/jira/browse/HDFS-10252?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Vinayakumar B resolved HDFS-10252.
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Resolution: Invalid
> Is DataNode aware of the name of the file that it is going to store?
> --------------------------------------------------------------------
>
> Key: HDFS-10252
> URL: https://issues.apache.org/jira/browse/HDFS-10252
> Project: Hadoop HDFS
> Issue Type: Test
> Components: datanode, namenode
> Reporter: Dimitrios Sarigiannis
> Priority: Minor
>
> I am going through the HDFS Namenode and Datanode code and I am trying to see if the DataNode is aware of the names of the files that are stored in it (and other metadata as well).
> Assuming that we have the most simple case:
> 1 NameNode
> 1 DataNode
> 1 single machine running HDFS with replication factor 1.
> and considering the way HDFS works a use case could be:
> A client requests to write a file from local to HDFS (for example: "hdfs dfs -put file /file")
> He first communicates with NameNode and gets where this file should be stored.
> Then, after receiving an answer, he requests to the DataNode to store that file.
> (At that point I am going to be a little more specific about the code)
> The DataNode has a DataXceiverServer class which runs and waits for requests. When a request comes, it starts a DataXceiver thread and try to serve that request. What I would like to know is, if at that specific point the DataNode knows the name of the file that it is going to store. I spent hours of debugging but I could not find it. Is it somewhere there, or only the NameNode knows the name of that file?
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