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From Pushkar Raste <pushkar.ra...@gmail.com>
Subject Re: restore quorum after majority of zk nodes down
Date Thu, 29 Oct 2015 22:46:09 GMT
How about having let's say 4 nodes on each side and make one node in one of
data centers a observer. When data center with majority of the nodes go
down, bounce the observer by reconfiguring it as a voting member.

You will have to revert back the observer back to being one.

There will be a short outage as far as indexing is concerned but queries
should continue to work and you don't have to take all the zookeeper nodes
down.

-- Pushkar Raste
On Oct 29, 2015 4:33 PM, "Matteo Grolla" <matteo.grolla@gmail.com> wrote:

> Hi Walter,
>       it's not a problem to take down zk for a short (1h) time and
> reconfigure it. Meanwhile solr would go in readonly mode.
> I'd like feedback on the fastest way to do this. Would it work to just
> reconfigure the cluster with other 2 empty zk nodes? Would they correctly
> sync from the nonempty one? Should first copy data from zk3 to the two
> empty zk?
> Matteo
>
>
> 2015-10-29 18:34 GMT+01:00 Walter Underwood <wunder@wunderwood.org>:
>
> > You can't. Zookeeper needs a majority. One node is not a majority of a
> > three node ensemble.
> >
> > There is no way to split a Solr Cloud cluster across two datacenters and
> > have high availability. You can do that with three datacenters.
> >
> > You can probably bring up a new Zookeeper ensemble and configure the Solr
> > cluster to talk to it.
> >
> > wunder
> > Walter Underwood
> > wunder@wunderwood.org
> > http://observer.wunderwood.org/  (my blog)
> >
> >
> > > On Oct 29, 2015, at 10:08 AM, Matteo Grolla <matteo.grolla@gmail.com>
> > wrote:
> > >
> > > I'm designing a solr cloud installation where nodes from a single
> cluster
> > > are distributed on 2 datacenters which are close and very well
> connected.
> > > let's say that zk nodes zk1, zk2 are on DC1 and zk2 is on DC2 and let's
> > say
> > > that DC1 goes down and the cluster is left with zk3.
> > > how can I restore a zk quorum from this situation?
> > >
> > > thanks
> >
> >
>

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