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From: Apache Wiki <wikidiffs@apache.org>
To: Apache Wiki <wikidiffs@apache.org>
Date: Wed, 09 Dec 2009 16:19:23 -0000
Message-ID: <20091209161923.20753.23620@eos.apache.org>
Subject: 
 =?utf-8?q?=5BCassandra_Wiki=5D_Update_of_=22Operations=22_by_JonathanElli?=
 =?utf-8?q?s?=

Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Cassandra Wiki" for=
 change notification.

The "Operations" page has been changed by JonathanEllis.
http://wiki.apache.org/cassandra/Operations?action=3Ddiff&rev1=3D8&rev2=3D9

--------------------------------------------------

   * !RackAwareStrategy: replica 2 is is placed in the first node along the=
 ring the belongs in '''another''' data center than the first; the remainin=
g N-2 replicas, if any, are placed on the first nodes along the ring in the=
 '''same''' rack as the first
  =

  Note that with !RackAwareStrategy, succeeding nodes along the ring should=
 alternate data centers to avoid hot spots.  For instance, if you have node=
s A, B, C, and D in increasing Token order, and instead of alternating you =
place A and B in DC1, and C and D in DC2, then nodes C and A will have disp=
roportionately more data on them because they will be the replica destinati=
on for every Token range in the other data center.
+  * The corollary to this is, if you want to start with a single DC and ad=
d another later, when you add the second DC you should add as many nodes as=
 you have in the first rather than adding a node or two at a time gradually.
  =

  Replication strategy may not be changed without wiping your data and star=
ting over.
 =20