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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: Reviewing . . . RackAwareStrategy.java . . . ( rev 954657 )
Date Tue, 15 Jun 2010 17:55:52 GMT
On Mon, Jun 14, 2010 at 11:03 PM, Masood Mortazavi
<masoodmortazavi@gmail.com> wrote:
> The comment on the top of RackAwareStrategy says:

You are correct.  RAS sort of works under other conditions but it is
primarily intended for 2 DCs and RF=3.  I will update the comment in
question.

> There are other issues to think about. For example, for quorum write
> (consistency.quorum) to work faster, shouldn't the first replicas be as
> close as possible (i.e. on the same rack)?  The whole point of choosing this
> level of consistency is to improve performance. Right?

No, the point is to improve reliability (there are a number of failure
scenarios that will result in losing an entire rack at once).

-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com

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