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MapReduce >> mail # user >> datanode write forwarding


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Jay Vyas 2012-12-18, 20:56
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Mohammad Tariq 2012-12-18, 21:07
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Harsh J 2012-12-18, 22:13
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Chris Embree 2012-12-18, 22:19
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Harsh J 2012-12-18, 22:31
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Re: datanode write forwarding
Hi Jay,

We'll need "real developer" expertise on this, but my understanding of the
documentation is:

Client talks to Name node to get Node/Block assignments,  client then talks
to node 1: write, fwd, node 2: write, fwd, node 3: write, ack node 2, node
2: ack node1, node 1: ack Client and Name Node.

write includes data write and checksum, ack = report success.  The fwd
requests happen AFTER successful write and checksum.

Hope this helps.
Chris

On Tue, Dec 18, 2012 at 3:56 PM, Jay Vyas <[EMAIL PROTECTED]> wrote:

> Hi :
>
> Do data nodes, when they receive write requests, forward the request to
> the next datanode in the chain after appending to a file? Or rather, do the
> write and forward asynchronously and at the same time?
>
> --
> Jay Vyas
> http://jayunit100.blogspot.com
>