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From Anand Somani <meatfor...@gmail.com>
Subject Re: Question on using consistency level with NetworkTopologyStrategy
Date Fri, 09 Sep 2011 16:53:28 GMT
Oh yes, that is cool. I see from the code now (was reading it incorrectly).

So a Quorum with NTS would give me 3 copies across the cluster, not
necessarily 2 local and 1 remote, but for most parts that would be true
since WAN adds to latency.

Thanks


On Thu, Sep 8, 2011 at 3:40 PM, Jonathan Ellis <jbellis@gmail.com> wrote:

> CL.QUORUM is supported with any replication strategy, not just simple.
>
> Also, Cassandra's optimizing of cross-DC writes only requires that it
> know (via a correctly configured Snitch) where each node is located.
> It is not affected by replication strategy choice.
>
> On Thu, Sep 8, 2011 at 3:14 PM, Anand Somani <meatforums@gmail.com> wrote:
> > Hi,
> >
> > Have a requirement, where data is spread across multiple DC for disaster
> > recovery. So I would use the NTS, that is clear, but I have some
> questions
> > with this scenario
> >
> > I have 2 Data Centers
> > RF - 2 (active DC) , 2 (passive DC)
> > with NTS - Consistency level options are - LOCAL_QUORUM and EACH _QUORUM
> > I want LOCAL_QUORUM and 1 remote copy (not 2) for write to succeed, if I
> > used EACH_QUORUM - it would mean that I need both the remote nodes up (as
> I
> > understand from http://www.datastax.com/docs/0.8/operations/datacenter).
> >
> > So if that is my requirement what consistency Level should I be using for
> my
> > writes? Is that even possible with NTS or another strategy? I could use
> the
> > SimpleStrategy with Quorum, but that would mean sending 2 copies (instead
> of
> > 1 per DC that NTS uses to optimize on WAN traffic) to remote DC (since it
> > does not understand DC's)?
> >
> > Thanks
> > Anand
> >
>
>
>
> --
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of DataStax, the source for professional Cassandra support
> http://www.datastax.com
>

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