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From Raghu Angadi <rang...@yahoo-inc.com>
Subject Re: Writes to HDFS
Date Tue, 07 Aug 2007 22:20:31 GMT
Phantom wrote:

> Basically my question is whether the namenode
> is involved in every write request.

No.

Name node is contacted once for each "block". If your block size is 64MB 
and you write 5GB file, namenode will be contacted once for each of the 
16 blocks and once for closing the file.

Raghu.

> Thanks
> A
> 
> On 8/7/07, Raghu Angadi <rangadi@yahoo-inc.com> wrote:
>>
>> To write data to HDFS, you should be able to connect to both Namenode
>> and to all of the datanodes. NameNode decides where to place the data
>> blocks and tells the client (you) to send the blocks to corresponding
>> datanodes.
>>
>> Raghu.
>>
>> Phantom wrote:
>>> Hi
>>>
>>> When I write data into HDFS do I always need to connect to the datanode
>> to
>>> write the data ? Can I connect to any namenode to do so ? If so how does
>> the
>>> datanode keep track of where the various chunks are going to be placed ?
>> Any
>>> resource that I can look at or could someone explain this to me ?
>>>
>>> Thanks
>>> A
>>>
>>
> 


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