That makes sense.  It still seems to conflict with what's stated in the wiki:

"...the remaining N-2 replicas, if any, are placed on the first nodes along the ring in the *same* rack as the first"

-Aaron


On Fri, Jun 11, 2010 at 11:20 AM, Jonathan Ellis <jbellis@gmail.com> wrote:
You're mis-parsing the first.  It says "place one replica in a
different datacenter, and the others on different racks in the same
one," where the antecedent of "one" is "datacenter," not rack.

On Fri, Jun 11, 2010 at 11:09 AM, Blew, Aaron <aaron.blew@iovation.com> wrote:
> The first text says the N-2 replicas are placed in the same rack while the
> second text indicates that the N-2 replicas will be placed in different
> racks.
> Am I missing something?
> -Aaron
> ---
> Aaron Blew -
> Sr. Infrastructure Engineer | The Automator
> iovation - The Power of Reputation™
> aaron.blew@iovation.com
> On Jun 11, 2010, at 10:48 AM, Jonathan Ellis wrote:
>
> I'm not sure what parts of these you think are in conflict.
>
> On Fri, Jun 11, 2010 at 10:34 AM, Blew, Aaron <aaron.blew@iovation.com>
> wrote:
>
> Hello,
>
> I was browsing the docs for the RackAware replication strategy and saw this
> on the wiki:
>
> "RackAwareStrategy: replica 2 is placed in the first node along the ring the
> belongs in another data center than the first; the remaining N-2 replicas,
> if any, are placed on the first nodes along the ring in the *same* rack as
> the first"
>
> However the storage.conf comments say the following:
>
> "Strategy: Setting this to the class that implements
> IReplicaPlacementStrategy will change the way the node picker works.  Out of
> the box, Cassandra provides org.apache.cassandra.locator.RackUnawareStrategy
> and org.apache.cassandra.locator.RackAwareStrategy (place one replica in a
> different datacenter, and the others on different racks in the same one.)"
>
> To me the comments in storage.conf make more sense since you'd want
> datacenter diversity for the data as well as rack level diversity within the
> local datacenter.  Which one is accurate?  Is the disparity a result of the
> wiki page not being updated after the behavior changed with a release?
>
> Thanks all,
>
> -Aaron
>
> ---
>
> Aaron Blew -
>
> Sr. Infrastructure Engineer | The Automator
>
> iovation - The Power of Reputation™
>
> aaron.blew@iovation.com
>
>
>
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> --
> Jonathan Ellis
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> co-founder of Riptano, the source for professional Cassandra support
> http://riptano.com
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--
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com