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From Vinod Kumar Vavilapalli <vino...@hortonworks.com>
Subject Re: HDFS data transfer is faster than SCP based transfer?
Date Fri, 24 Jan 2014 18:19:11 GMT
Is it a single file? Lots of files? How big are the files? Is the copy on a
single node or are you running some kind of a MapReduce program?

+Vinod
Hortonworks Inc.
http://hortonworks.com/


On Fri, Jan 24, 2014 at 7:21 AM, rab ra <rabmdu@gmail.com> wrote:

> Hi
>
> Can anyone please answer my query?
>
> -Rab
> ---------- Forwarded message ----------
> From: "rab ra" <rabmdu@gmail.com>
> Date: 24 Jan 2014 10:55
> Subject: HDFS data transfer is faster than SCP based transfer?
> To: <user@hadoop.apache.org>
>
> Hello
>
> I have a use case that requires transfer of input files from remote
> storage using SCP protocol (using jSCH jar).  To optimize this use case, I
> have pre-loaded all my input files into HDFS and modified my use case so
> that it copies required files from HDFS. So, when tasktrackers works, it
> copies required number of input files to its local directory from HDFS. All
> my tasktrackers are also datanodes. I could see my use case has run faster.
> The only modification in my application is that file copy from HDFS instead
> of transfer using SCP. Also, my use case involves parallel operations (run
> in tasktrackers) and they do lot of file transfer. Now all these transfers
> are replaced with HDFS copy.
>
> Can anyone tell me HDFS transfer is faster as I witnessed? Is it because,
> it uses TCP/IP? Can anyone give me reasonable reasons to support the
> decrease of time?
>
>
> with thanks and regards
> rab
>

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