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Date: Mon, 2 May 2011 14:09:53 -0400 (EDT)
From: Robert Jackson <robertj@promedicalinc.com>
To: user@cassandra.apache.org
Message-ID: <1286734955.74355.1304359793510.JavaMail.root@mail>
In-Reply-To: <BANLkTi=74OB3AgKqVT=PfxJVd5XKZa_D3w@mail.gmail.com>
Subject: Re: Specifying exact nodes for Consistency Levels
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The only way I can think of would be to use NetworkTopologyStrategy and PropertyFileSnitch to define two data centers. Set node1-node3 in DC1 then set node4 in DC2. Then set the strategy_options=[{DC1:3, DC2:1}] for that keyspace. 

This would make your cluster conceptually similar to a split datacenter as described in the Brisk white paper. 

References: 

http://www.datastax.com/docs/0.7/operations/datacenter 
http://www.datastax.com/wp-content/uploads/2011/03/WP-Brisk.pdf 

Robert Jackson 

----- Original Message -----
From: "A J" <s5alye@gmail.com> 
To: user@cassandra.apache.org 
Sent: Monday, May 2, 2011 1:26:31 PM 
Subject: Specifying exact nodes for Consistency Levels 

Is it possible in some way to specify what specific nodes I want to 
include (or exclude) from the Consistency Level fulfillment ? 
Example, I have a cluster of 4 nodes (n1,n2,n3 and n4) and set N=4. I 
want to set W=3 and want to ensure that it is n1,n2 and n3 only that 
are used to satisfy w=3 (i.e. n4 is excluded for w=3 calculation). 

Thanks. 

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<html><head><style type=3D'text/css'>p { margin: 0; }</style></head><body><=
div style=3D'font-family: Times New Roman; font-size: 12pt; color: #000000'=
><span>The only way I can think of would be to use </span>NetworkTopologySt=
rategy and PropertyFileSnitch to define two data centers.&nbsp; Set node1-n=
ode3 in DC1 then set node4 in DC2.&nbsp; Then set the strategy_options=3D[{=
DC1:3, DC2:1}] for that keyspace.<br><br>This would make your cluster conce=
ptually similar to a split datacenter as described in the Brisk white paper=
. <br><br>References:<br><br>http://www.datastax.com/docs/0.7/operations/da=
tacenter<br>http://www.datastax.com/wp-content/uploads/2011/03/WP-Brisk.pdf=
<br><span id=3D"3DF8EE7C-D20D-11DC-BDD4-727394E5A07E"><span name=3D"x"></sp=
an><br>Robert Jackson<br></span><br><hr id=3D"zwchr"><b>From: </b>"A J" &lt=
;s5alye@gmail.com&gt;<br><b>To: </b>user@cassandra.apache.org<br><b>Sent: <=
/b>Monday, May 2, 2011 1:26:31 PM<br><b>Subject: </b>Specifying exact nodes=
 for Consistency Levels<br><br>Is it possible in some way to specify what s=
pecific nodes I want to<br>include (or exclude) from the Consistency Level =
fulfillment ?<br>Example, I have a cluster of 4 nodes (n1,n2,n3 and n4) and=
 set N=3D4. I<br>want to set W=3D3 and want to ensure that it is n1,n2 and =
n3 only that<br>are used to satisfy w=3D3 (i.e. n4 is excluded for w=3D3 ca=
lculation).<br><br>Thanks.<br></div></body></html>
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