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Date: Fri, 19 Sep 2014 08:34:52 -0400
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 <CAEo-6+RydRAoobogq72Szk8veD0fn2K=vBV43jGU-Y8AKrhgGA@mail.gmail.com>
Subject: Re: Query regarding the replication factor in hadoop
From: Shahab Yunus <shahab.yunus@gmail.com>
To: "user@hadoop.apache.org" <user@hadoop.apache.org>
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Your write will not succeed. You will get an exception like "xxxx could
only be replicated to 0 nodes, instead of 1"

More details here:
http://www.bigdataplanet.info/2013/10/Hadoop-Tutorial-Part-4-Write-Operations-in-HDFS.html
http://cloudcelebrity.wordpress.com/2013/11/25/handling-hadoop-error-could-only-be-replicated-to-0-nodes-instead-of-1-during-copying-data-to-hdfs-or-with-mapreduce-jobs/
http://wiki.apache.org/hadoop/CouldOnlyBeReplicatedTo


Regards,
Shahab

On Fri, Sep 19, 2014 at 8:16 AM, Raghavendra Chandra <
raghavchandra.learning@gmail.com> wrote:

> Hi All,
>
> I have one very basic query regarding the replication factor in HDFS.
>
> Scenario:
>
> I have 4 node cluster : 3 data nodes and 1 master node.
>
> The replication factor is 3. So ideally each data node would  get one
> replica .
>
> Assume that meanwhile one of the data node went down.
>
> so ideally we will be having 2 data nodes.
>
> Queries:
>
> 1. How hadoop will take care of balancing of replicas as the required
> replicas are 3 , but we have only 2 data nodes up and running.
>
> 2. What happens when we try to write new  data into hdfs at this point of
> time ? whether the write would be successful with only 2 data nodes and
> replication factor 3 or it returns any error message?
>
>
> These queries might be simple, but it would be really helpful if some one
> can answer.
>
> Thanks and regards,
> Raghav Chandra
>
>

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<div dir=3D"ltr">Your write will not succeed. You will get an exception lik=
e &quot;xxxx could only be replicated to 0 nodes, instead of 1&quot;<div><b=
r></div><div>More details here:</div><div><a href=3D"http://www.bigdataplan=
et.info/2013/10/Hadoop-Tutorial-Part-4-Write-Operations-in-HDFS.html">http:=
//www.bigdataplanet.info/2013/10/Hadoop-Tutorial-Part-4-Write-Operations-in=
-HDFS.html</a><br></div><div><a href=3D"http://cloudcelebrity.wordpress.com=
/2013/11/25/handling-hadoop-error-could-only-be-replicated-to-0-nodes-inste=
ad-of-1-during-copying-data-to-hdfs-or-with-mapreduce-jobs/">http://cloudce=
lebrity.wordpress.com/2013/11/25/handling-hadoop-error-could-only-be-replic=
ated-to-0-nodes-instead-of-1-during-copying-data-to-hdfs-or-with-mapreduce-=
jobs/</a><br></div><div><div><a href=3D"http://wiki.apache.org/hadoop/Could=
OnlyBeReplicatedTo">http://wiki.apache.org/hadoop/CouldOnlyBeReplicatedTo</=
a><br></div></div><div><br></div><div><br></div><div>Regards,</div><div>Sha=
hab</div></div><div class=3D"gmail_extra"><br><div class=3D"gmail_quote">On=
 Fri, Sep 19, 2014 at 8:16 AM, Raghavendra Chandra <span dir=3D"ltr">&lt;<a=
 href=3D"mailto:raghavchandra.learning@gmail.com" target=3D"_blank">raghavc=
handra.learning@gmail.com</a>&gt;</span> wrote:<br><blockquote class=3D"gma=
il_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-lef=
t:1ex"><div dir=3D"ltr">Hi All,<div><br></div><div>I have one very basic qu=
ery regarding the replication factor in HDFS.</div><div><br></div><div>Scen=
ario:</div><div><br></div><div>I have 4 node cluster : 3 data nodes and 1 m=
aster node.</div><div><br></div><div>The replication factor is 3. So ideall=
y each data node would =C2=A0get one replica .</div><div><br></div><div>Ass=
ume that meanwhile one of the data node went down.=C2=A0</div><div><br></di=
v><div>so ideally we will be having 2 data nodes.</div><div><br></div><div>=
Queries:</div><div><br></div><div>1. How hadoop will take care of balancing=
 of replicas as the required replicas are 3 , but we have only 2 data nodes=
 up and running.</div><div><br></div><div>2. What happens when we try to wr=
ite new =C2=A0data into hdfs at this point of time ? whether the write woul=
d be successful with only 2 data nodes and replication factor 3 or it retur=
ns any error message?</div><div><br></div><div><br></div><div>These queries=
 might be simple, but it would be really helpful if some one can answer.</d=
iv><div><br></div><div>Thanks and regards,</div><div>Raghav Chandra</div><d=
iv><br></div></div>
</blockquote></div><br></div>

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