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Date: Tue, 10 Jul 2012 06:31:33 -0400
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Subject: Re: Can Observers be reconfigured in a DR situation?
From: David Nickerson <davidnickerson4mailinglists@gmail.com>
To: user@zookeeper.apache.org
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Hi Raj,

I've been considering this same solution for my project. Let's say that the
secondary DC automatically makes its own quorum when it can no-longer see
the primary. Then you have a case where a network partition can result in
your quorum splitting into two autonomously running quorums. (ZooKeeper's
majority rule exists to prevent this situation.) Just make sure that you
have some additional logic that invalidates the primary once it can
no-longer be found.

On Tue, Jul 10, 2012 at 3:39 AM, C=E9sar =C1lvarez N=FA=F1ez <
cesar.alvarez.nunez@gmail.com> wrote:

> Yes you can. Just edit the zoo.cfg from the  backup DC, comment the lines
> relative to the nodes in the primary DC and the observer peer type.
>
> In this way you can start a new ZK ensemble with just the 3 servers on
> backup DC.
>
> But be aware that due to latency issues the backup DC could not have the
> latest changes from the active DC.
>
> You will also need to update each client "connection string" to use only
> the servers from the backup DC.
>
> /Sent from my GP0.
> El 09/07/2012 23:16, "Raj N" <raj.cassandra@gmail.com> escribi=F3:
>
> > Let's say you have 2 DCs, primary and secondary. The primary DC has a 3
> > node zookeeper quorum. And the secondary DC has 3 nodes that are
> observers.
> > Is it possible in a DR scenario(primary down) to make the 3 observer
> nodes
> > the new quorum?
> >
> > Thanks
> > -Raj
> >
>

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