The quorum is the minimun, so it depends on how many you have running in the
ensemble. If it's three or four, then two is the quorum and therefore the
minumum. Three is regarded as a minumum in the ensemble because two makes no
sense.
-----Original message-----
> From:Jack Krupansky <j...@basetechnology.com>
> Sent: Thu 06-Dec-2012 15:53
> To: solr-user@lucene.apache.org
> Subject: Re: Minimum HA Setup with SolrCloud
>
> "but if those same machines are running zookeeper, you need 3."
>
> And one of those 3 can go down? I thought 3 was the minimum number of
> zookeepers.
>
> -- Jack Krupansky
>
> -----Original Message-----
> From: Mark Miller
> Sent: Thursday, December 06, 2012 9:30 AM
> To: solr-user@lucene.apache.org
> Subject: Re: Minimum HA Setup with SolrCloud
>
> It depends on if you are running embedded zk or an external zk ensemble.
>
> One leader and a replica is all you need for Solr to allow on machine to go
> down - but if those same machines are running zookeeper, you need 3.
>
> You could also run zookeeper on one external machine and then it would be
> fine if you lost one solr node - but if you the one external zk node went
> down you would lose the ability to do updates until it was brought back up.
>
> - Mark
>
> On Dec 6, 2012, at 2:46 AM, Thomas Heigl <tho...@umschalt.com> wrote:
>
> > Hey all,
> >
> > I'm in the process of migrating a single Solr 4.0 instace to a SolrCloud
> > setup for availability reasons.
> >
> > After studying the wiki page for SolrCloud I'm not sure what the absolute
> > minimum setup is that would allow for one machine to go down.
> >
> > Would it be enough to have one shard with one leader and one replica?
> > Could
> > this setup tolerate one of the instances going down? Or do I need three
> > instance because Zookeeper needs a quorum of instances?
> >
> > Cheers,
> >
> > Thomas
>
>
