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From: Ran Tavory <rantav@gmail.com>
Date: Mon, 7 Jun 2010 14:26:15 +0300
Message-ID: <AANLkTik9suauPUq4PLSkVBL6P3lPZZDyZ28DB6V_paMV@mail.gmail.com>
Subject: Re: Is ReplicationFactor values number of replicas or number of
	copies of data?
To: user@cassandra.apache.org
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to have two copies you need RF=2.
RF=0 doesn't make sense as far as I understand it.

On Mon, Jun 7, 2010 at 2:16 PM, Per Olesen <pol@trifork.com> wrote:

> Hi,
>
> I am unclear about what the ReplicationFactor value means.
>
> Does RF=1 mean that there is only one single node that has the data in the
> cluster (actually no replication), or, does it mean, that there are two
> copies of the data - one "actual" and one "replica" (as in "replicated one
> time")?
>
> I noticed, that I CAN start a node with RF=0, but I get
> UnavailableException when trying to insert, so I assume RF=0 is wrong then?
>
> Put another way: If I want my data to always live on exactly 2 nodes in the
> cluster, do I set RF=2 or RF=1? :-)
>
> /Per

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<div dir=3D"ltr">to have two copies you need RF=3D2.<div>RF=3D0 doesn&#39;t=
 make sense as far as I understand it.<br><br><div class=3D"gmail_quote">On=
 Mon, Jun 7, 2010 at 2:16 PM, Per Olesen <span dir=3D"ltr">&lt;<a href=3D"m=
ailto:pol@trifork.com">pol@trifork.com</a>&gt;</span> wrote:<br>

<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex;">Hi,<br>
<br>
I am unclear about what the ReplicationFactor value means.<br>
<br>
Does RF=3D1 mean that there is only one single node that has the data in th=
e cluster (actually no replication), or, does it mean, that there are two c=
opies of the data - one &quot;actual&quot; and one &quot;replica&quot; (as =
in &quot;replicated one time&quot;)?<br>


<br>
I noticed, that I CAN start a node with RF=3D0, but I get UnavailableExcept=
ion when trying to insert, so I assume RF=3D0 is wrong then?<br>
<br>
Put another way: If I want my data to always live on exactly 2 nodes in the=
 cluster, do I set RF=3D2 or RF=3D1? :-)<br>
<font color=3D"#888888"><br>
/Per</font></blockquote></div><br></div></div>

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