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From Matteo Grolla <matteo.gro...@gmail.com>
Subject Re: restore quorum after majority of zk nodes down
Date Fri, 30 Oct 2015 09:34:17 GMT
Pushkar... I love this solution
      thanks
I'd just go with 3 zk nodes on each side

2015-10-29 23:46 GMT+01:00 Pushkar Raste <pushkar.raste@gmail.com>:

> 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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